CTBT: Science and Technology Conference 2023 - SnT2023

Europe/Vienna
Hofburg Palace & Online

Hofburg Palace & Online

Hofburg Palace, Vienna, Austria
Description

The Preparatory Commission for the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) relies on innovation to enhance the capabilities of the Treaty’s verification regime as well as to help move the Treaty closer to universalization and entry into force. As the seventh event in the CTBT: Science and Technology conference series, SnT2023 will bring together well over 1000 scientists, technologists, academics, students, and representatives of the CTBTO’s policy making organs. In addition, representatives from the fields of research and development, science diplomacy, science advisory, media and advocacy are invited to attend the conference.

SnT2023 is scheduled to take place at the Hofburg Palace in Vienna, Austria, featuring virtual components for active online participation to support broader outreach and global inclusiveness. While restrictions on physical attendance at SnT2023 due to COVID-19 are not currently foreseen, the structure of the conference will be hybrid and remain flexible in order to adapt to any circumstances as needed.

Report and Executive Summaries:

 

The SnT Support Team
    • 08:45
      Welcome coffee
    • High-Level Opening Festsaal

      Festsaal

      The programmme of the High-Level Opening (HLO) is under preparation.

      Interpretation in all UN languages will be available for in-person attendance in the Festsaal.

      • 1
        High Level Opening - CTBT: Science and Technology Conference 2023

        Welcome video

        Opening
        • Dr Robert Floyd, CTBTO Executive Secretary

        High Level Remarks
        • Ms Izumi Nakamitsu, United Nations Under-Secretary-General and High Representative for Disarmament Affairs (video message)
        • His Excellency Mr Abshir Omar Jama Huruse, Minister of Foreign Affairs and International Cooperation of Somalia
        • Mr Rafael Grossi, Director General of the International Atomic Energy Agency
        • Mr Mayen Dut Wol, Undersecretary, Ministry of Foreign Affairs and International Cooperation of South Sudan
        • Ms Alinne Olvera Martinez, Early-Career Women in STEM CTBTO Mentoring Programme

        Keynote Address
        • Ms Jill Hruby, Under Secretary of Energy for Nuclear Security and Administrator of the National Nuclear Security Administration of the United States

        Musical Interlude
        • Trio KlaVis

        High Level Panel
        “CTBT Science and Technology: Benefitting us all”
        • His Excellency Mr Li Song, Permanent Representative of the People's Republic of China
        • Ms Dwikorita Karnawati, Director of the Indonesian Agency for Meteorology, Climatology and Geophysics and Chair of the Intergovernmental Coordination Group of Indian Ocean Tsunami Warning and Mitigation System
        • Mr Geoff Brumfiel, Senior Editor and Correspondent, Science Desk at NPR
        • Ms Antonietta Rizzo, Head of Laboratory for Methods and Techniques for Nuclear Safety, Monitoring and Traceability, Italian National Agency for New Technologies, Energy and Sustainable Economic Development
        • Ms Xyoli Perez Campos, Director of the International Monitoring System Division of the CTBTO

        Master of Ceremonies: Ms Monika Jones, Freelance TV Anchor

    • 12:30
      Lunch
    • Panel discussion on francophonie Festsaal

      Festsaal

      Interpretation in all UN languages will be available for in-person attendance in the Festsaal.

      • 2
        L’apport de la francophonie dans les discussions internationales

        L’objectif de cette table ronde de haut niveau est de souligner le rôle de la francophonie et le multilinguisme comme facilitateur des discussions internationales. Des ambassadeurs rompus à ces échanges apporteront leur ressenti sur le sujet.

        Speaker: Agnès Chanut (Le Cercle)
    • 15:15
      Coffee break
    • Panel discussion on EU - CTBTO cooperation Festsaal

      Festsaal

      Interpretation in all UN languages will be available for in-person attendance in the Festsaal.

      • 3
        European Union - CTBTO Cooperation in action

        The European Union (EU) remains a staunch supporter of the CTBT and its Organisation, both politically and financially. Promoting the universalisation and entry into force of the CTBT is a top priority for the EU, in line with its non-proliferation and disarmament policies and objectives.
        In the framework of the EU Strategy against the Proliferation of Weapons of Mass Destruction, the EU has provided voluntary contributions to the CTBTO through eight EU Council Decisions to date, amounting to almost 30 million EURO, in order to strengthen its monitoring and verification capabilities. The extensive support provided by the European Union for the Treaty and its verification regime will be the focus of this panel discussion. In this regard, the benefits of technical and capacity-building programs funded by the European Union will be presented by those who benefit from the implementation and the output of the projects.

        • Opening remarks by His Excellency Mr Stephan Klement, Head of Delegation of the European Union to International Organisations in Vienna
        • Closing remarks by Dr Robert Floyd, CTBTO Executive Secretary
        Speaker: Ms Elena Thoma (EU Delegation to International Organisations in Vienna)
    • 17:00
      Cocktail reception [To be updated]
    • Arabic-speaking panel Prinz Eugen Saal

      Prinz Eugen Saal

      • 4
        Mutual benefits between Arabic-speaking countries and the CTBTO

        To be updated
        [This panel discusses the mutual benefits between the CTBTO and Arabic-speaking countries. For many local experts engaging in the operation of IMS stations and serving at the National Data Centres (NDC) having the training and capacity-building materials in Arabic is beneficial. An excellent example was set with the NDC training for Arabic-speaking NDCs that was held in January 2020 at the Red Sea in Egypt. The NDCs in Arabic-speaking countries actively monitor nuclear explosion and prepare for On-site Inspection. Regional experts have made many significant contributions in using IMS data and advancing analysis methods for events in the region, such as the investigation of the unfortunate large atmospheric explosions of Beirut in 2020 or to studying natural disasters like the severe earthquakes in the Türkiye - Syria region in February 2023. Civil applications are also important for the region, IMS data are used for tsunami early warning in the Mediterranean. The organisation of the Integrated Field Experiment 2014 (IFE14) in Jordan provided important knowledge to prepare On-site Inspections, which will be relevant for future experiment.
        The panel will be conducted in Arabic, giving an overview of recent experiences on the use of IMS data for verification purposes. The potential benefits for civil and scientific applications will also be discussed, in particular how the IMS technologies (waveform and radionuclide networks) can possibly complement other observation methods. The discussion will also cover the importance of regional cooperation between NDCs.]

        Speaker: Abdelouaheb Agrebi (Former CTBTO Preparatory Commission)
    • French-speaking panel Forum

      Forum

      • 5
        Renforcement des capacités régionales en Afrique francophone

        English title: Regional capacity building for IMS station managers and operators in French-speaking countries in Africa

        This panel discusses operational strategies and challenges faced by managers and operators of International Monitoring System stations in French-speaking countries in Africa. The objective is to strengthen the capabilities of operators in order overcome the challenges encountered in their countries.
        Admittedly, the hurdles confronted by station operators and managers may differ from one country to another or even between station locations. Yet there may be common challenges for which experience exchange and synergies could offer solutions. One of the questions that will be addressed by the panel is how to initiate new operational strategies to improve the activities of station managers and operators in the region. Such strategies could focus on various elements such as, for example, digital connectivity, energy supply, equipment transportation, the security context. It could also investigate synergies between National Data Centres (NDC) in the region as a mean to strengthen capabilities of the stakeholders and the operation of IMS stations.
        The panel will be conducted in French, with experienced station managers and operators from French-speaking countries in Africa, some of them also staff of NDCs.

        Speaker: Mr Gerard Rambolamanana (CTBTO Preparatory Commission)
    • Spanish-speaking panel Festsaal

      Festsaal

      • 6
        The role of CTBT IMS data to support disaster risk mitigation

        Disasters affect populations on a global scale. The Latin American and the Caribbean (LAC) region, is frequently impacted by large earthquakes, tsunamis, volcanic eruptions, and extreme weather events (drought and tropical storms). The raising awareness and concern about the need for disaster risk mitigation, highlights the necessity for operating multi-technology platforms to understand better the hazards posed by natural phenomena.
        Currently, IMS data are provided to 20 Tsunami Warning Centres (TWC) in 19 countries that signed a Tsunami Warning Agreement with the CTBTO, this includes two TWCs in the LAC region (Chile and Honduras). IMS data are delivered reliably, timely and securely. This contributes to the work of TWCs since 2005. As this civil application evolves, progresses are also achieved on scientific applications relevant to earthquake monitoring, volcano eruption monitoring for aviation and maritime safety.
        The panel will be conducted in Spanish, giving an overview of recent experiences on the use of IMS data for TWCs in the LAC region and Spain. The potential benefits for civil and scientific applications will be discussed, in particular how the IMS technologies (waveform and radionuclide networks) can possibly complement other observation methods. The dialog will also assess how regional cooperation between National Data Centres (NDCs) among each other and with disaster warning centres may offer perspectives to further mitigate the risk of disasters.

        Speaker: Ms Xyoli Pérez Campos (CTBTO Preparatory Commission)
    • Lightning talks: P1.3, P1.4, P5.2 Wintergarten

      Wintergarten

      • 7
        Modeling Low Frequency Acoustical Propagation in a Shallow-Water Wedge

        In shallow-water environments long range propagation proceeds by repeated reflections from the surface and the bottom of the channel, as is the case for underwater sound of a wide spectral range, whose very low frequencies may propagate over large distances, without significant losses. In this paper, a 3-D benchmark model of the fluid wedge over an elastic bottom is applied to explain low frequency long range propagation in shallow water overlaying a sloping elastic-type seabed, such as a sedimentary rock exhibiting rigidity. The modeling approach is based on the modified method of generalized ray that furnishes a complete acoustic signal, thus comprised of contributions from all of the wave motions typical for the model (not only from the source signal and the regularly [specularly] reflected waves but also from the refracted [lateral] waves and the pseudo-Rayleigh and the Scholte interface waves), received in order of their arrivals at a large distance from the point source. When the source emits signals of a low frequency content, the contribution from the Scholte waves becomes dominant at large distances. Hence, low frequency long range propagation in a shallow-water wedge (coastal wedge) may indeed be governed by the Scholte waves.

        Speaker: Piotr Borejko (TU Wien)
      • 8
        Changes in the Noise Levels of the Indian Ocean and their Relationship to Shipping Patterns

        Long term observations using hydrophones installed by the CTBTO in the Indian Ocean, suggest that noise levels increased from 2002 to around 2012. Since then they have been decreasing. While the increase in noise levels was related to growth in ship traffic, the reasons for the decrease are not known. This paper investigates the reasons for the decrease in two steps. The first step builds an acoustic model that uses shipping densities from the Automatic Identification System (AIS) for several years to simulate ship positions in the Indian Ocean. The ship positions are then used to model the low frequency noise levels due to cargo and tanker traffic. The second step further incorporates other inputs in the model, such as potential changes in ship velocities, and observations of long term oceanographic changes to investigate the drift in noise levels. Preliminary results suggest that a potential decrease in ship speeds is the reason for the reduction in noise levels.

        Speaker: Tarun Chandrayadula (Indian Institute of Technology Madras)
      • 9
        Historical Tsunami in Eastern Mediterranean

        The eastern Mediterranean Basin was always the main trade route and cultural exchange between the old-world continents. Being centered in the middle of the three continents, the region is often referred to as the cradle of civilization. Meanwhile, it has suffered several catastrophic events, including earthquakes and Tsunamis. Due to its populated coasts, the possibility to record damage and casualties provided one of the longest historical tsunami and earthquake catalogues in the world. In this paper, we investigate the coastal deposits to find high energy deposits and correlate them to the historical tsunami catalogue to provide insights into the size and impact of such events. The results showed a strong impact of large tsunamis from the Hellenic arc on the Egyptian coasts but also left open questions about possible unrecorded tsunamis in our historical catalogues.

        Speaker: Mohamed Nabil Mohamed ElGabry (National Research Institute of Astronomy and Geophysics (NRIAG))
      • 10
        Anthropogenic Noise in the sea: The Mediterranean Sea Versus Ocean Basins

        Anthropogenic noise pollution may mask natural sounds, which are fundamental to survival and reproduction of wildlife, especially for marine cetaceans as they are highly dependent on underwater sounds for basic life functions. In the 21st century, shipping in the ocean has increased significantly and causes low frequency (10–100 Hz) noise which affects or hinders vital communication of large baleen whales at 15 to 30 Hz. Noise in the ocean has been monitored as a byproduct by International Monitoring System stations of the CTBTO. However, elsewhere for example at ocean gateways or in marginal seas little is known about the soundscape. Here, we report long term and short term low frequency noise measurements from Gibraltar, the gateway into the Mediterranean Sea and from the Pelagos Sanctuary, a Marine Protected Area, in the Ligurian Sea, Mediterranean. Ambient noise is derived from calibrated moored ocean-bottom-hydrophones deployed for earthquake monitoring and seismic campaign work. Observations are compared to noise levels in the range of 1 to 100 Hz as revealed at CTBTO monitoring sites in the Atlantic, Indian and Pacific Ocean. Most profoundly, noise levels in the Mediterranean and near Gibraltar are significantly higher by up to 20 dB at 40 Hz when compared to the open oceans.

        Speaker: Prof. Ingo Grevemeyer (GEOMAR Helmholtz Centre for Ocean Research)
      • 11
        Hydroacoustic Modeling in a Rapidly Evolving Arctic Ocean

        The Arctic Ocean is rapidly warming. The hydroacoustic environment will be impacted by the changing thermohaline structure, increased marine traffic, changes in sea ice coverage, and possible increases in microseism/storm noise. This will inevitably lead to obsolescence for today’s ocean acoustic models. The only sophisticated way to make predictions is using decadal to centennial integrations of fully coupled Earth system models (ESMs). At the Los Alamos National Laboratory we are working to create the first version of an ESM, the Department of Energy’s Energy Exascale Earth System Model (E3SM), capable of driving an acoustics model in a rapidly evolving Arctic Ocean. Here we analyse existing E3SM simulations to investigate how well we currently capture water properties for the upper 1000 m of the Arctic water column, including changes that could impact acoustic wave propagation. We present preliminary results of model validation against temperature and salinity observations from ice-tethered ocean profilers. The goal of this effort is to provide boundary ocean conditions to the acoustic model, to enable quantification of the ocean acoustic implications of climate change as well as to create a climate aware atlas of global acoustic noise and propagation adjustments for non-proliferation signal detection.

        Speaker: Ms Siobhan Niklasson (Los Alamos National Laboratory (LANL))
      • 12
        Comparison of Ambient Noise Between Ocean-Bottom Seismic Networks

        Seismic sensors have traditionally been largely restricted to on-land installations, yet the oceans comprise roughly 70% of the Earth's surface. Coupled with heterogeneous distribution of seismicity, this results in many regions being poorly sampled for Earth model development, and poorly monitored for detection of natural and anthropogenic seismic sources. To mitigate this deficiency, extending our seismic measurements and observations into the oceans is an important future direction in seismology. Sea floor seismic sensing may mitigate many monitoring issues from a geometric perspective, but the ambient noise level recorded by ocean-bottom seismometers (OBS) is in general much higher than the ambient noise levels on land. Details of the sea floor noise regime are not well described, and to exploit the broadest regions for potential instrumentation, we must characterize the noise environment to aid in selection of sites for permanent sensors. We present a preliminary comparison of seafloor seismic noise at several temporary sea floor deployments, located in different parts of the global ocean. We detail how noise varies as a function of oceanographic, meteorological, and other dynamic variables at these sites. Our aim is to eventually develop a worldwide dynamic sea floor seismic noise model to guide us in optimizing future deployments for seismic monitoring.

        Speaker: Ms Siobhan Niklasson (Los Alamos National Laboratory (LANL))
      • 13
        Extending the Boundary Element Method to Three-Dimensional Acoustic Propagation Problems in the Ocean

        Recently, some efforts have been made to apply the Boundary Element Method (BEM) to propagation problems in shallow waters, motivated by its neat mathematical formulation and the fact that, unlike other 3-D methods, only 2-D boundary integration is required. However, its chances of becoming a real competitor in the area are undermined by the large sizes of the discretized computational boundaries and by the inhomogeneities in the wave equation resulting from the non-uniform sound speeds that any realistic ocean description requires. Here, we present and discuss results concerning a BEM formulation aimed at predicting sound propagation in an ocean environment of arbitrary bathymetry. A marching scheme is considered so that only a fraction of the total computational domain (the bathymetry) needs to be handled at once thus providing an affordable way to tackle long range propagation problems. The parameters required for an appropriate domain partition crucially depend on the features of the bathymetry, involving in general an irregular step size. Additionally, a set of theoretical integral equations are presented that take into account the sound speed inhomogeneities by using surface and volume potentials. Finally, the numerical schemes obtained from this theoretical formulation are shown, as well as some implementation details.

        Speaker: Mr Edmundo Lavia (Argentinian Navy Research Office (ARA) & UNIDEF (CONICET))
      • 14
        Determining Crustal Attenuation With Seismic T Waves in Southern Africa

        Crustal attenuation structures obtained at high frequencies (>1 Hz) are important for seismic risk assessment and geodynamics studies in stable continents. However, it is difficult to infer attenuation in low seismicity regions using body and surface waves. In this study, we explore the potential of using seismic T phases to constrain the crustal attenuation. We analysed the characteristics of T waves recorded on the seismic array deployed in southern Africa. The converted station-side T-P and T-S phases were identified by analysing the waveform, travel time, polarization, and frequency-wavenumber features. The distinct differences in polarization and slowness are used to quantify contributions from T-P and T-S conversions. The inverted frequency dependent Qp and Qs (attenuation factor of local P and S waves, respectively) in the southern Africa are found to be 204f^1.48 and 685f^0.53, respectively. Our method could be extended to infer crustal attenuation features near the coasts of other continents.

        Speaker: Dr Yong Zhou (South China Sea Institute of Oceanology, Chinese Academy of Sciences)
      • 15
        Continuous Analysis of International Monitoring System Hydrophone Array Signals for the Detection of Submarine Volcanic Activity

        International Monitoring System hydrophone stations are useful for the monitoring of submarine volcanic activity, especially in the western Pacific Ocean. Therefore, we started to routinely analyse the signals of triplet H11S, located off the coast of Wake Island, from July 2022 onwards. The SeedLink server of the Incorporated Research Institutions for Seismology (IRIS) provides the data; the SeisComP5 software is used for access and storage in daily mseed files. We process one-day hydrophone data as follows: 1. Removing the instrument response, 2. Band-pass filtering of the waveforms (4-8 Hz), 3. Semblance analysis to determine the incoming direction and apparent velocity across the triplet per 10-s time window, using intervals of 1° and 0.002 km/s (1.45 to 1.55 km/s), respectively, 4. The results are posted on our internal website. The obtained maximum semblance values typically vary from 0.5 to 0.9, and only values ≥ 0.7 are interpreted to be significant.

        Speaker: Mr Satoru Tanaka (Japan Agency for Marine-Earth Science and Technology (JAMSTEC))
      • 16
        Retrieval of Sea Surface Current using Himawari-8 SST Data and Particle Image Velocimetry Method in the Flores Sea

        Surface ocean currents are important maritime weather parameters because they influence both human activity and the global climate. In Indonesia, real time observations of surface ocean currents are currently made using HF-Radar installed in two locations, one of which is the Flores Sea. Because observational data is still scarce, efforts to provide surface ocean current data are required. One of the techniques used is the use of Himawari-8 geostationary satellite data on Sea Surface Temperature (SST). Particle Image Velocimetry (PIV), which is based on the cross-correlation technique, was used to calculate surface ocean currents from Himawari-8 SST data. The short term analysis of Himawari-8 SST in the Flores Sea during the northern summer shows
        a high SST with values reaching 31 ̊C, especially around the north coast of Flores Island. Meanwhile, the south coast of Flores Island shows a low SST with a value of less than 26 ̊C. The direction of movement of surface ocean currents in the Flores Sea varies with the dominant direction towards the West according to the synoptic wind direction where the Australian monsoon occurs. Validation with HF radar data shows a similar pattern of ocean currents with a correlation value of up to 0.6.

        Speaker: Kadek Setiya Wati (Indonesian Agency for Meteorology Climatology and Geophysics)
      • 17
        A Recent Episode of Submarine Volcanic Activity in the South Sandwich Arc – Insights from International Monitoring System Hydrophone and T Phase Station Data

        We present a recent example for the civil and scientific application of International Monitoring System (IMS) hydroacoustic data. On 24 April 2022, IMS stations detected a cluster of impulsive, seismoacoustic events in the South Sandwich Arc, a volcanically active chain of remote islands and seamounts in the southern Atlantic Ocean. Preliminary results from automated and interactive analysis of hydrophone and T phase station data suggest that these events, which occurred over a period of less than two hours and which were preceded by at least two hour-long episodes of low level tremor, are likely volcanic in nature, and originated at or near one of several recently discovered seamounts offshore Candlemas and Saunders Island. Our findings are consistent with waveform data gathered by non-IMS stations as well as satellite observations and further highlight the potential of the IMS hydroacoustic network for detecting and studying submarine volcanic activity in some of the most remote regions on the planet.

        Speaker: Mr Dirk Metz (CTBTO Preparatory Commission)
      • 18
        Improvements to Hydroacoustic Processing Utilizing Three-Dimensional Ocean Acoustic Propagation

        In support of the Comprehensive Nuclear-Test-Ban Treaty, the International Monitoring System (IMS) has implemented a set of deep water open ocean hydroacoustic stations for monitoring (detecting and localization) any nuclear tests. As acoustic propagation satisfies the acoustic wave equation sound is subject to three-dimensional effects (refraction, diffraction, reflections) when in the presence of horizontal gradients due to bathymetry, oceanography or the presence of continents. The current processing system ignores these effects (using in-plane propagation for all acoustic paths) and has large error bars in azimuth for event association. In this work, a set of acoustic propagation codes are being used to integrate 3-D propagation into the automated event localization algorithm as well as into the IMS analyst work flow. A summary of the acoustic models as well as demonstrations of observed 3-D phenomenon for large underwater events will be presented as well as a programme plan to update the IMS processing approach.

        Speaker: Kevin Heaney (Applied Ocean Sciences)
      • 19
        Detection of Infrasound Sources using Array Data from 2019 to 2021 Deployed at the Lützow-Holm Bay Region, Antarctica

        Time-space variations of infrasound source locations from 2019 to 2021 were studied using a combination of two local arrays in the Lützow-Holm Bay (LHB), Antarctica. The local arrays deployed at two outcrops clearly detected temporal variations in frequency content as well as propagating directions during the three years. A large number of infrasound sources were detected and many of them located in N-NW directions from the arrays. These source events were generated within the Southern Indian Ocean to the northern part of LHB with frequency content of a few seconds; that is the microbaroms from oceanic swells. From austral summer to fall season, many infrasound sources orientation are determined to be north-eastward direction. These sources might be related to the effect of katabatic winds of the continental coastal area. Furthermore, several sporadic infrasound events during winter seasons had predominant frequency content of a few Hz, which are clearly higher than microbaroms. On the basis of a comparison with sea-ice and glacier distribution form MODIS satellite images, these high frequency sources were considered to be cryoseismic signals associated with cryosphere dynamics. In this regard, infrasound could be a useful tool to monitor surface environment involving climate change in the coastal area of Antarctica.

        Speaker: Masaki Kanao (National Institute of Polar Research)
      • 20
        On the Infrasound Emission Generated by Large Wind Turbines

        Aerodynamic infrasonic signals generated by large wind turbines can be detected by highly sensitive micro-barometers showing spectral peaks at the blade passing harmonics, which are above the background noise level. As infrasound is one of the four verification technologies for the compliances with the Comprehensive Nuclear-Test-Ban Treaty, decreases in detection capability for dedicated infrasound arrays have to be avoided. Therefore, for BGR preventing such decrease is particularly important for IS26 and IS27, which are International Monitoring Stations infrasound arrays and have to meet stringent specifications with respect to their infrasonic ambient noise levels.
        In 2004, infrasonic signatures of a single horizontal-axis wind turbine were measured during a field experiment. As one of the results, a minimum distance to wind turbines for undisturbed recording conditions at infrasound array IS26 was estimated based on numerical modelling, validated with this dataset. Nevertheless, for broadening the dataset further infrasound measurements at two wind parks with modern large wind turbines have recently been carried out. Here various instruments (micro-barometers, microphones, pressure sensors) have been deployed in a comparative manner. An overview of these campaigns is given followed by first results of analysis and interpretation.

        Speaker: Lars Ceranna (Federal Institute for Geosciences and Natural Resources (BGR))
      • 21
        End to end Numerical Simulation of a Comet’s Reentry, Impact, Cratering, Fireball and Cloud Generation: Local and Global Consequences

        Simulations of a 1 to 2 km comet striking Earth on solid ground and on ocean waters have been conducted. Models include hydrostatic equilibrium profiles of temperature, pressure, and densities for atmosphere and ocean, in order to accurately predict impact consequences. Phase changes, such as melting and vaporization, combined with the material’s tensile, shear, and compressive strength responses, under high temperature and high strain conditions, along with anisotropic responses, are considered in greater detail than in previous work. Our simulations illustrate the erosion of the comet and the creation of a dusty tail, the breakup of the comet into fragments, the erosion of some of the fragments, and the survival of others. The reentry of fragments into the stratosphere and their flattening is also demonstrated. For the first time, we present results of an integrated simulation of water and ground impact, the resulting crater formation, fireball evolution and cloud generation and transport of dust and debris to hundreds of kilometers from the impact site. We illustrate the seismoacoustic signature of an asteroid impacting Earth. Computations were conducted on LLNL HPC using SME++ framework developed over the last 7 years.

        Speaker: Mr Souheil Ezzedine (Lawrence Livermore National Laboratory (LLNL))
      • 22
        Timing Statistics of the Multiple Passages of the Pressure Wave Generated by the 2022 Hunga Tonga- Hunga -Ha’apai and Comparison with the 1883 Krakatoa Pressure Wave

        The Hunga Tonga - Hunga Ha’apai (HTHH) eruption of 15 January 2022 was an exceptional event by the period, magnitude, and duration of propagation of the atmospheric waves it generated, circling the globe multiple times. Even though several volcanic eruptions in the past 150 years era of scientific instrumentation generated notable barometric disturbances, the HTHH eruption is comparable only to the Krakatoa eruption of 1883 by the magnitude of the atmospheric pressure waves that it generated. The very energetic Mt Pinatubo eruption of 1991 did not produce pressure waves of the same period and magnitude as the Krakatoa or HTHH eruptions. An analysis of the timing of the multiple passes at barometric stations is reported in Symons (1888) for the Krakatoa. Since the HTHH event gave rise to the only pressure wave to have circled the Earth’s atmosphere multiple times in the last 139 years, it is of interest to perform similar timing statistics on the multiple passages at stations that recorded them. A review of the Krakatoa analysis and a comparison with the HTHH are presented, with possible implications for the changes in the global state of the atmosphere during the interval between the two events.

        Speaker: Mr Ronan Le Bras (Former CTBTO Preparatory Commission)
      • 23
        Integrated Analysis Based on all-sky Cameras and Infrasonic Array for the Characterization of Small Fireball Events

        The entry meteoroids and meteorites into the earth's atmosphere is a powerful source of infrasonic waves. The generated infrasound can be recorded at the ground and, using an array of sensors, characterized in terms of wave parameters, indicative of the source and its position. This study presents the integrated analysis of ~15 small fireball events based both on images of the all-sky cameras of the PRISMA meteor surveillance network and on the infrasonic data recorded at two infrasonic arrays deployed by the University of Florence in Northern and Central Italy. Thanks to the analysis of the light signals recorded by multiple all-sky cameras, the detected events were physically characterized in terms of time of occurrence, observed optical trajectory and pre-atmospheric speed, mass, dimensions and kinetic energy. Using the occurrence time provided by the all-sky cameras, the recorded signals, analysed through array processing, are back-propagated using ray-tracing techniques to reconstruct the infrasound propagation, locate the fireball event and reconstruct its trajectory.
        Finally, the optically derived parameters are compared with the infrasonic amplitude retrieved at the source and with the frequency content of the recorded infrasonic signals, to investigate the potential of using infrasound to reconstruct the energy of the meteoroid events.

        Speaker: Mr Giacomo Belli (University of Firenze (UNIFI))
      • 24
        High Precision Characterization of Seismicity from the 2022 Hunga Tonga-Hunga Ha'apai Volcanic Eruption

        The earthquake swarm accompanying the January 2022 Hunga Tonga-Hunga Ha’apai (HTHH) volcanic eruption includes many post-eruptive moderate magnitude seismic events and presents the unique opportunity to use remote monitoring methods to characterize and compare seismic activity to other historical caldera-forming eruptions. We compute improved epicentroid locations, magnitudes, and regional moment tensors of seismic events from this earthquake swarm using regional to teleseismic surface wave cross correlation and waveform modeling. Precise relative locations of 91 seismic events derived from 59047 intermediate period Rayleigh and Love wave cross correlation measurements collapse into a small area surrounding the volcano and exhibit a southeastern time dependent migration. Regional moment tensors and observed waveforms suggest that these events are a similar mechanism and exhibit a strong positive CLVD component. Precise relative magnitudes agree with regional moment tensor MW estimates, while also showing that event sizes and frequency increase during the days after the eruption, followed by a period of several weeks of less frequent seismicity of a similar size. Our analysis of the HTHH eruption sequence demonstrates the value of potentially utilizing teleseismic surface wave cross correlation and waveform modeling methods to assist in the detailed analysis of remote volcanic eruption sequences.

        Speaker: Mr Jonas Kintner (Los Alamos National Laboratory (LANL))
      • 25
        Hydroacoustic SignalsConverted at Coastal International Monitoring System Stations

        The hydroacoustic International Monitoring System (IMS) network was designed to detect underwater nuclear explosions. Two types of stations belong to this network. Six of them record signals with hydrophone triplets placed in the Sound Fixing and Ranging (SOFAR) channel. Remaining five are T phase, seismic stations which detect hydroacoustic signal converted to seismic wave at a steep shore slope. T phase stations measure arrival time but, unlike in case of hydrophone stations, do not provide other detection parameters (i.e. azimuth estimate). Analysts consider correlation with signals at other stations or observations for similar events to include T phase station detections in event solutions. Hydroacoustic signals generated by large magnitude seismic events are also observed at coastal seismic or infrasound IMS stations, which are configured to measure detection parameters, i.e. azimuth, or slowness. Correct identification of such signals will help analysts to include them in International Data Centre bulletins. Investigation of these additional hydroacoustic data will also allow to estimate whether detection parameters can increase confidence in correct associations of T phase station detections.

        Speaker: Paulina Bittner (CTBTO Preparatory Commission)
      • 26
        Seismoacoustic Monitoring of Wind Turbines Around a Proposed Einstein Telescope Site

        Wind turbines emit vibrations due to the rotation of the blades and the movement of the tower. Vibrations radiated from wind turbines are known to interfere with operational seismoacoustic monitoring of natural and induced seismicity. Additionally, the contribution of such vibrations to the ambient seismoacoustic noise field can significantly hinder the performance of sensitive optical systems. One such example is the Einstein Telescope, a subsurface gravitational-wave detector, currently under development. The sensitivity of the Einstein Telescope is strongly affected by the ambient seismoacoustic noise field. To characterize the noise generated by wind turbines in the region of interest, we deployed five seismic mini-arrays west of the Aachen wind park and recorded the ambient seismic field over the course of 35 days. In addition to analysing the power spectral density at each station, we employ array-processing techniques to identify and characterize various sources in the region. Our analysis indicates that the amplitude of distinct spectral peaks decreases as a function of distance from the wind park. Additionally, we found that the amplitude, of the entire spectrum, but specifically of these spectral peaks is in correlation with wind speed.

        Speaker: Shahar Shani-Kadmiel (Royal Netherlands Meteorological Institute (KNMI))
      • 27
        The Volcanic Ash Dispersion Simulation of Huge Volcanic Eruption with the PUFF Lagrangian Method : A case Study of Tonga Eruption 15 January 2022

        The PUFF Model is a volcanic ash dispersion model used in Indonesia to help predict the distribution of volcanic ash for aviation safety purposes. This model uses the Lagrangian method taking into account wind, diffusion, and gravity parameters. The eruption of Mount Tonga on 15 January 2022 with a volcanic explosivity index (VEI) of 5 which exceeded Galunggung 1982 and Kelud 2014 is an interesting phenomenon to study with the PUFF model because of the relatively large distribution of ash eruptions. Volcanic eruptions with VEI >= 3 have different characteristics from VEI <3 which often occur in Indonesia. The simulation is carried out by changing the value of the diffusion parameter in the model and comparing it with satellite imagery to find a suitable value for a large type of eruption. It was found that increasing the value of the diffusion coefficient can increase the accuracy of the distribution of volcanic ash. The accuracy of the volcanic ash distribution area is very significant for flight safety.

        Speaker: Mr I Kadek Nova Arta Kusuma (Meteorology, Climatology, and Geophysical Agency of Indonesia (BMKG))
      • 28
        Data Analysis of the Hunga-Tonga-Hunga-Ha’apai Eruption and Mauna Loa Eruption with Three International Monitoring System Technologies

        The eruption of the Hunga-Tonga-Hunga-Ha’apai volcano on 15 January 2022 was the largest recorded since the eruption of Krakatoa in 1883. The eruption triggered tsunami waves of up to 15m which struck the west coast of Tongatapu, ‘Eua and Ha’apai.
        In this work we analyse data of this event. With a magnitude of mb 4.2 at 04:14:59 UTC, the eruption was detected by the three International Monitoring System (IMS) technologies. This work includes data analysis with the HA11 and HA3 hydroacoustic stations with the integration of the location of the event with the seismic and infrasound data of the stations close to the event. In addition we analyse signals related to the Mauna Loa eruption from infrasound, seismic and hydroacoustic IMS stations, which detected an event located in Hawaii, USA, 28 November 2022 at 08:56 UTC.

        Speaker: Ms Yasameen Hameed Shamkhi (Iraqi National Monitoring Authority)
      • 29
        Seismoacoustics Wavefield Generated by the Beirut Explosion: An Application of the Unfitted Hybridizable Discontinuous Galerkin Model

        Understanding and predicting seismoacoustic waveforms may be a real conundrum, depending on the complexity of the source term, but also on the geological features a wavefield is propagating through. Transmission of elastic energy (i.e. coupling) between the solid Earth and fluid layers (atmosphere, ocean) can bring a wealth of information about the characteristics of a source, but may be highly dependent on the geological settings (topography). To overcome these challenges, two numerical tools are presented that can deal efficiently with the propagation of elastic wavefields in complex media. The first is an extension of the now classical finite spectral-element method (SEM) to the so-called hybridizable discontinuous Galerkin (HDG) model. The HDG-formulation allows to mitigate meshing constraints inherent to the SEM at a reasonable numerical cost, by introducing hybrid and nonconforming meshes. Also implemented in the HDG software, the second tool goes further, in the sense that without any loss of numerical convergence, material interfaces need not fit element boundaries, which is the classical paradigm in finite element methods; one coins these, unfitted or cut (finite) elements. Both tools are applied to simulate the accidental Beirut explosion and help to understand seismic conversions in the near-field of the source and receivers.

        Speaker: Mr Laurent Guillot (Commissariat à l’énergie atomique et aux énergies alternatives (CEA))
      • 30
        Acoustic Data Analysis of the Tonga Submarine Volcanic Eruptions in January 2022

        One of the sources of acoustic signals is underwater volcanic eruptions. Climatic phase of such underwater eruptions results in an ash cloud being ejected into the stratosphere thus generating infrasound signals while at the same time generating acoustic signals. The active volcano in Hunga Tonga-Hunga Ha'apai (HTHH) one of the Tonga Island groups erupted violently on 15 January 2022 triggering tsunamis. International Monitoring System (IMS) infrasound and hydroacoustic stations recorded the event from the foreshock to aftershock. Submarine and subaerial components were identified in the study of acoustic signals obtained from these IMS stations. A complex source sequence was detected by the stations analysed during the eruption phase. DTK-GPMCC was used to study the wave properties with the time frequency bands at lower frequency (0.001-1Hz). The wave parameters of back-azimuth, frequency, the root-mean-square amplitude, and the apparent velocity were calculated. Result of the event showed acoustic gravity, Lamb wave and infrasonic features. This study is an indication of the importance of IMS stations towards the understanding of submarine volcanic eruptions.

        Speaker: Mr Uchenna Onwuhaka Madu (Nigeria Atomic Energy Commission (NAEC))
      • 31
        Stratospheric Balloon Observations of Infrasound Waves from the 15 January 2022 Hunga Eruption, Tonga

        The 15 January 2022 eruption of the Hunga volcano (Tonga) generated a rich spectrum of waves, some of which achieved global propagation. Among numerous platforms monitoring the event, two stratospheric balloons flying over the tropical Pacific provided unique observations of infrasonic wave arrivals, detecting five complete revolutions. Combined with ground measurements from the infrasound network of the International Monitoring System, balloon-borne observations may provide additional constraint on the scenario of the eruption, as suggested by the correlation between bursts of acoustic wave emission and peaks of maximum volcanic plume top height. Balloon records also highlight previously unobserved long range propagation of infrasound modes and their dispersion patterns. A comparison between ground and balloon based measurements emphasizes superior signal to noise ratios onboard the balloons and further demonstrates their potential for infrasound studies.

        Speaker: Christophe Millet (Commissariat à l’énergie atomique et aux énergies alternatives (CEA))
      • 32
        Climate Change, Global Warming, Tsunamis, Earthquakes and the Role of the CTBTO

        There is a heated debate in the scientific community about possible effects of changes on the planet's surface due to global warming, frequency and magnitude of earthquakes, and tsunamis triggered by earthquakes. Some studies point to seasonal modulations of deep slow slip and earthquakes in the main thrust of the Himalayas or increased risks at coastlines. One aspect that everyone seems to agree on is the instantaneity and level of destruction. Adding to the danger is that each State is responsible for issuing warnings to its population through National-Tsunami-Warning-Centres or similar authorities. The decision to issue an alert is based on its own analysis of the situation. Along with earthquake alerts, CTBTO has provided valuable tools and knowledge to improve research and development content in this area.
        This study evaluates the advances of the States that are affected by earthquakes, that have coasts in the Caribbean, that could be negatively affected by the foreseeable actions of Climate Change, to guide the technological prospective actions in the creation of their own alert centres for climate change, earthquakes, tsunamis and the interaction of these as a large network that might be led by CTBTO.

        Speaker: Roberto Betancourt A. (Venezuelan Foundation of Seismological Research (Funvisis))
      • 33
        Analysis of Potential Impact of Tsunami in West Papua due to North West Papua Earthquake Using TOAST Modeling

        Indonesia is a relatively high seismic activity region and one of the most active areas is the West Papua. TOAST is a software used for tsunami modeling simulations that can provide results quickly and in real time. Analysis of the impact of the tsunami using TOAST shows that based on the earthquake scenario on 10 October 2002 for the magnitudes varying from 7.0 to 8.0, the highest tsunami wave was recorded in the northern Sorong area with a height from 0.066 to 3.345 meters. Meanwhile, with a magnitude from 8.5 to 9.0, a tsunami was recorded in the Manokwari area with a height from 1.976 to 2.906 meters. The fastest estimated time arrival (ETA) was recorded in the northern Sorong area with an interval of about 3 minutes. For the earthquake scenario on 3 January 2009 with a magnitude between 7.0 to 8.5, the highest run-up was recorded in the Wondama Bay area with a height from 0.178 to 5.546 meters. For a magnitude of 9.0, it was recorded in Manokwari with a wave height of 2.906 meters and the fastest ETA was recorded in the Wondama Bay area with an interval from 8.25 to 8.5 minutes.

        Speaker: Ms Lestari Naomi Lydia Pandiangan (Meteorology, Climatology, and Geophysical Agency of Indonesia (BMKG))
      • 34
        Community Preparedness for Tsunami Disaster: A Case Study for Tsunami Ready Community in Glagah Village, Kulon Progo, Yogyakarta - Indonesia

        The activity of the subduction zone in the south of Java island has been generating severe earthquakes and tsunami events in the past. This natural disaster made the southern region of Java, including the Yogyakarta special region (DIY), prone to incoming tsunamis. Kalurahan Glagah, a village in the south part of DIY, is one of 1,013 villages in Indonesia that has a high tsunami vulnerability, so it is necessary to prepare its community for a tsunami that can occur at any time.
        We have assisted the local government in increasing the preparedness of its people in dealing with the tsunami. Through the capacity building program such as Earthquake Field School and providing detailed tsunami hazard maps using the worst-case scenario. Based on numerical modeling results, we identify that the Mw8.8 earthquake can generate a tsunami wave as high as 22 m with a wave arrival time of 38 minutes on the coastline of DIY. The existence of Yogyakarta International Airport in Glagah Village as an earthquake-resistant structure means that this airport can be utilized as a vertical evacuation place. The synergy between stakeholders has received national recognition from Indonesia's National Tsunami Ready Board and seeking international recognition by UNESCO Intergovernmental Oceanographic Commission.

        Speaker: Mr Setyoajie Prayoedhie (Meteorology, Climatology, and Geophysical Agency of Indonesia (BMKG))
      • 35
        Seismic and Volcanic Networks in Real Time of Instituto Geofísico in Ecuador: Performance, Evaluation and Optimization

        The Instituto Geofísico of the Escuela Politécnica Nacional (IGEPN) is in charge of the monitoring and study of seismic and volcanic activity in the Ecuadorean territory. The networks include monitoring seismic, volcanic and geodetic networks with 105 seismic stations, 11 infrasound sensors, 67 strong motion sensors, 65 GPS of high accuracy and more than 56 stations for lahar detection, gas analysis and visual monitoring in active volcanoes; all of them with real time transmission provided by different and independent technologies: satellite, microwave owned by IGEPN, fiber-optic with 16 nodes in different places in Ecuador, Internet and own subnets with analog or digital radios, which represent 90% of all instrumentation installed in Ecuador. This maintains the National Processing Center for Issuing Seismic and Volcanic Alerts, which operates 24/7 and supplies the information by email, fax, radio, Telegram, Facebook, Twitter and website automatically three minutes after seismic event occurs. This article describes actual network coverage, performance, evaluation and optimization of real time transmission network, with analysis from 2016 to present.

        Speaker: Mrs Cristina Ramos (Instituto Geofísico de la Escuela Politécnica Nacional (IGEPN))
      • 36
        Climate Change and the Increased of Registered Seismic Events, Effects in the Caribbean

        Scientific data shows that glaciers are melting due to Climate Change driven by global warming with some results showing an impact in the amount of seismic activity. If glaciers thawed, the enormous weight bearing down on the Earth's crust is reduced, experiencing what geologists refer to as a “post-glacial rebound." This process might reactivate faults and lift pressure on the subterranean reservoirs containing molten silicate fluid beneath a volcano in subduction zones an oceanic plate moves under another plate, therefore increasing seismic activity. Using correlation coefficient and regression analysis based on two previous case studies, this paper explores the relationship between temperature rise due to global warming and earthquake frequency in the Carribean Basin.

        Speaker: Mr Roberto Betancourt A. (Fundacion Venezolana de Investigaciones Sismologicas (FUNVISIS))
      • 37
        Preserving Past Tsunami Banggai 2000

        Past earthquakes in the Banggai area were not widely reported. Lack of information on the source mechanism and the tsunami made it difficult to obtain a complete picture of the disaster events. The earthquake and tsunami on May 4, 2000 is one example. The tsunami earthquake that occurred, although very local in nature, had quite an impact in some locations. However, generating mechanism correlated with earthquake sources, propagation and affected areas is not sufficient and raises a number of questions.
        Using historical global seismic data, we identify the characteristics of the earthquake's source and propagation in the Banggai region. Investigation of the source mechanism's characteristics also revealed that the tsunami was generated by sources other than tectonic earthquakes, such as a submarine landslide. This indication is reinforced by the result of field surveys that show non-uniformity of inundation in the affected areas. This study of the historical earthquake and tsunami impact is critical to determine disaster impact in the future. It serves as an input and reference for the local government's disaster mitigation efforts.

        Speaker: Ms Litanya Octonovrilna (Meteorology, Climatology, and Geophysical Agency of Indonesia (BMKG))
      • 38
        Integrating CTBTO Data in Academic Research of Environmental Science and Disaster Management in Bangladesh

        Bangladesh, a major part of the Bengal Basin, is an earthquake prone country due to its location at the junction of two major tectonic plates. The complicated geology of this basin is responsible for occurring several major and minor earthquakes in Bangladesh and its adjacent areas. The consequence of the earthquake and other natural disasters would be devastating for the country and its surplus population, and faulty and unplanned infrastructures. The Department of Environmental Science and Disaster Management of Daffodil International University has the scope of initiating a wide range of academic research covering such geological, environmental and disaster related courses. Seismic data analysis to obtain information on crust-mantle boundary or deep geological layering in this area could be one of the important aspects among this research. The department has strong collaboration with the National Data Centre of Bangladesh under CTBTO through which such research can be implemented. Seismic travel time data, radionuclide distribution, and hydroacoustic data towards tsunami early warning system, climate change investigation etc. from the virtual Data Exploitation Centre (vDEC) could be utilized through academic activities of various students, who are the representatives of youth in Bangladesh. This will contribute to improve the disaster preparedness systems of the country.

        Speaker: Ms Mahfuza Parveen (Daffodil International University (DIU))
      • 39
        Effect of the Monsoon on Radioactivity Concentrations of Pb-212F and Be-7 in Particulate Matter at THP65

        IDC data of radioactivity concentration of natural radionuclides in particulate matter collected at THP65 station have been studied their behaviors over a year. A significant difference of radioactivity concentrations of Pb-212F and Be-7 between wet and dry seasons has been found. North-east and south-west monsoons occurring on dry and wet seasons have been discussed their impacts on level of radionuclides. It is concluded that the air mass, including associated particular matter, originating over the Asian landmass is directed into Thailand by the north-east monsoon in the dry season and moist air from the Gulf brought into Thailand in the wet season are the reasons why radioactivity concentrations of Pb-212F and Be-7 in particular matter at the THP65 are higher and lower during the dry and wet seasons.

        Speaker: Thawatchai Itthipoonthanakorn (Office of Atoms for Peace)
      • 40
        Observed Tidal Effects in the Fine Temperature Variations Measured in a Deep Underground Tunnel of the Northern Caucasus Geophysical Observatory of IPE RAS

        The location of the Northern Caucasus Geophysical Observatory of the Institute of Physics of the Earth, Russian Academy of Sciences (IPE RAS) in the immediate vicinity of the magma chamber of the Elbrus volcano makes it possible to obtain unique data on the structure and dynamics of the thermal field in its vicinity. A precision temperature observation system was developed at the IPE RAS some years ago. During this time, we received first results of observations of natural temperature variations with an accuracy of up to one thousandth of a degree. The observed diurnal and semidiurnal harmonics found in microvariations of the underground temperature may be associated with the convective component of heat and mass transfer, which is largely determined by the corresponding changes in the regime of regular fluid migration due to the periodic influence of the combined solar-lunar tide effects on the geophysical medium in the deep underground tunnel. Estimation of the contributions of the conductive and convective components to the heat flow will make it possible to draw conclusions about the dynamics of the fluid-magmatic system of the Elbrus volcanic center and study the mode of its functioning, and can also be used directly for monitoring volcanic hazard.

        Speaker: Valentin Gravirov (The Schmidt Institute of Physics of the Earth of the Russian Academy of Sciences (IPE RAS))
      • 41
        Use of the Auxiliary Seismic Station APG (AS-037) for the Analysis of a Seismic Sequence in the North Region of Guatemala

        On January 4, 2018, two earthquakes reported by the population were recorded in the northern region of Guatemala. These were characterized with the National Seismological Network (RSN), however another thirty-nine earthquakes of smaller magnitude could only be recorded by the Auxiliary Seismic Station APG (AS-037) due to the high standards that its facility meets for its use in monitoring of possible nuclear explosions.
        This paper describes the use of APG (AS-037) for the characterization of these earthquakes (arrival times seismic waves, epicentral distances, magnitude and possible location) and their possible association with local geological faults, using techniques for the description of a seismic sequence using a single seismic station. These results provided important information for the subsequent proposal to improve the RSN in the region.
        Currently, Instituto Nacional de Sismología, Vulcanologia, Meteorologia e Hidrología
        (INSIVUMEH) has expanded its network of seismological stations, of which APG has been integrated into the permanent monitoring routines, being one of those with the highest detectability of both local, regional and distant earthquakes. In addition, it has the cooperation of seismological networks of neighboring countries. Consequently, the seismic catalog in has increased the number of recorded earthquakes, with a better quality of information and knowledge of seismic hazard.

        Speaker: Mr Robin Yani Quiyuch (NDC-INSIVUMEH)
      • 42
        CTBTO Virtual Data Exploitation Centre (VDEC) as a Way to Access Data Collected by the International Monitoring System

        Data collected by the International Monitoring System (IMS) represent four complementary technologies: seismic, hydroacoustic, infrasound and radionuclide. The main objective of acquiring IMS data is to detect and identify nuclear explosions on land, in the oceans, and in the atmosphere. However, the data are also extremely valuable for scientific studies e.g., to investigate the migration pattern and population density of marine mammals, or to track radiation on a global scale. These applications provide a benefit to the main purpose of detecting nuclear explosions by improving monitoring algorithms and our ability to discriminate between explosion signals and what is considered noise from the CTBT perspective. The vast amount of IMS data archived over two decades can be accessed via the virtual Data Exploitation Centre (vDEC). After signing a zero-cost vDEC contract (which contains legal requirements), scientists and researchers from many different disciplines and from around the globe, can get access to the IMS data to conduct research and to publish new findings. This presentation provides insights related to the vDEC platform and gives a statistical overview of all past and current scientific applications, including several examples of topics addressed with IMS data accessed under vDEC contracts.

        Speaker: Jolanta Kusmierczyk-Michulec (CTBTO Preparatory Commission)
      • 43
        Climate Change as Observed by the CTBTO Radionuclide IMS Stations: the Case of Spitzbergen

        The International Monitoring System (IMS), installed and maintained by the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) with the support of States Signatories, is a global system of monitoring stations composed of four complementary technologies: seismic, hydroacoustic, infrasound and radionuclide. One of the IMS radionuclide stations is located in Spitzbergen, a place where, based on many lines of evidence, the signs of climate change are noticeable. Spitzbergen is the largest island of the Norwegian Svalbard archipelago, in the Arctic Ocean. Warming of the atmosphere and oceans has been accompanied by sea level rise and a strong decline in Arctic Sea ice. Among other natural radionuclides, Pb-212 is always observed at IMS stations, in varying quantities, including at the Spitzbergen station RN49. The increase of surface temperature has an influence on the amount of Pb-212 released from the ground surface. This study based on almost twenty years of measurements (2003-2022) by the CTBTO demonstrates that variations of Pb-212 activity concentrations may be connected to climate variations.

        Speaker: Jolanta Kusmierczyk-Michulec (CTBTO Preparatory Commission)
      • 44
        Review on the Use of IMS Radionuclide Observations for Scientific Studies Related to the Fukushima Daiichi Nuclear Power Plant Accident

        In the months following the Fukushima Daiichi nuclear power plant accident, the IMS radionuclide stations observed elevated concentrations of anthropogenic radionuclides throughout the northern hemisphere. These data are available for scientific research through the virtual Data Exploitation Centre (vDEC) after signing a cost-free confidentiality agreement with the CTBTO. Part of these radionuclide concentrations were given to UNSCEAR for inclusion in their 2013 report. These data are highlighted in its scientific Annex on “Levels and effects of radiation exposure due to the nuclear accident after the 2011 great east-Japan earthquake and tsunami” as being unique in terms of the global coverage and the broader range of radionuclides than reported elsewhere, including four radioxenon isotopes. This presentation reviews the use of these data in dozens of peer-reviewed scientific papers. The most frequent application is the reconstruction of the source term for 137Cs, 131I, and 133Xe. Further applications include studies of wet deposition rates, enhancements for atmospheric transport modelling methods, reconstruction of release patterns, assessment of reactor damage, and environmental impact.

        Speaker: Mr Martin B. Kalinowski (CTBTO Preparatory Commission)
      • 45
        Preventing the Effects of Natural Disasters and Nuclear Test with the CTBT Verification Technologies for Myanmar

        Myanmar is exposed to multiple natural disasters including cyclones, earthquakes, tsunamis etc. Myanmar has signed tsunami warning agreements with CTBTO. Myanmar can access IMS database and IDC products. These data together with national natural disaster monitoring means will be used to identify disaster prone areas of the country. Creating public knowledge about disaster prone areas and the level of vulnerability to lives and properties in disaster events is key in disaster safety planning. If there is any nuclear accident or test in neighboring countries, Myanmar has activities for environmental radiological monitoring. To enhance the quality and coherence of decision making following nuclear emergency, working group of Myanmar has participated in JRODOS (Real-time On-line Decision Support System) exercises from EU. Myanmar has proposed locations of MMC, GDRMS and SWDRMS around the country. After the Fukushima incident occurred, IDC’s radiation database has been used to inform local people on the distribution of radiation in the atmosphere. Myanmar has also participated in the ConvEx exercises from IAEA and is a member of Establishing a Regional Early Warning Radiation Monitoring Network and Data Exchange Platform in ASEAN to mitigate hazard and to save lives from natural disasters.

        Speaker: Aye Aye Thin (Ministry of Education)
      • 46
        Seismic Network Expansion in the Caucasus and Central Asia (SNECCA)

        With support from the U.S. Department of Energy, Lawrence Livermore National Laboratory and the Incorporated Research Institutions for Seismology are collaborating with seismic monitoring centers in the Caucasus and Central Asia to expand national seismic networks through the installation of permanent broadband seismic stations. The main goal of the project is to improve regional network coverage by making high quality data from new stations openly available to the global scientific community. The multi-year project involves deployment of more than fifty posthole broad-band sensors across six participating countries: Armenia, Azerbaijan, Georgia, Kazakhstan, Kyrgyzstan, and Tajikistan. Additionally semi broad-band stations will be deployed for local monitoring of volcano and mud-volcano sites in Armenia and Azerbaijan; and standalone urban type strong motion sensors will be deployed in large cities. To facilitate data exchange and incorporate diverse sources of real-time data into national monitoring solutions, the project also supports the installation of high-capacity servers for participating monitoring centers. Station deployments began in the summer of 2021 and are planned to be completed in 2023. The project is implemented through the Seismic Targeted Initiative of the International Science and Technology Center in Kazakhstan and the Science and Technology Center in Ukraine.

        Speaker: Andrea Chiang (Lawrence Livermore National Laboratory (LLNL))
      • 47
        Monitoring Volcanoes of the World with IMS Infrasound Network: Evaluation of the Reliability of a New Detection Algorithm

        Detecting and notifying ongoing volcanic eruptions is crucial in supporting the Volcanic Ash Advisory Centres. However, local monitoring systems are missing at many active volcanoes. Long range infrasound monitoring, potentially able to detect and notify volcanic explosive events, might provide useful information. Indeed, many studies have already highlighted the utility of long range infrasound for this aim, but still open questions remain concerning its actual efficiency and reliability.
        In this study we investigate the potential of International Monitoring System infrasound network of CTBTO to remotely detect volcanic explosive eruptions, focusing on the main active volcanic area in the world, between 2010 and 2019, where multiple eruptions occurred, with an energy spanning from mild explosions to Volcanic Explosivity Index ≥ 4 eruptions.
        We applied a detection algorithm developed at local distance and extended for long range volcano infrasound monitoring. To assess the reliability of the algorithm, based on the Infrasound Parameter (IP), we compare the notifications issued with the bulletins reports of GVP (Global Volcanism Program). Although unresolved ambiguity remains due to short spacing among volcanoes with respect to the array and the unfavourable propagation conditions, the algorithm is able to detect in quasi real time the ongoing activity with high notification reliability.

        Speaker: Mr Duccio Gheri (University of Firenze (UNIFI))
      • 48
        First results from Tsunami Warning Agreement Between CTBTO and NDC Madagascar

        This is the first study after the signature of the tsunami warning agreement between the CTBTO and Madagascar in 2019. On 2nd of August 2019 12:03:23 UTC, an earthquake of magnitude 7 occurred south-west of Sumatra Indonesia and generated a local tsunami warning. The goal of this project is to monitor tsunami events using International Monitoring System seismic stations, then to simulate an inundation effect on the east coast of Madagascar with Community Model Interface for Tsunami (ComMIT) software developed by NOAA Center for Tsunami Research (NCTR). This event was observed from seismic and hydroacoustic stations as defined in “Hydroacoustic data analysis before and after the pandemic plus its contribution to Tsunami warning system in the Indian Ocean”. As a result, wave arrival time was 12:09 UTC at CMAR seismic station with 21 minutes of signal duration. Then, inundation effect was shown in some area with an average of 1m ocean wave amplitude.

        Speaker: Mr Jean Bernardo Andrianaivoarisoa (Institute and Observatory of Geophysics of Antananarivo (IOGA))
      • 49
        Volcanic Ash Risk Map and Mitigation Plans on Indonesian Aviation Service Using Geospatial Techniques (A Case Study of Bali Airport During Mount Raung, Agung, and Rinjani Eruption))

        Volcanic ash cause airports to alter or close their operations when it was detected around the airport and the flight routes. Bali airport is one of the busiest airports in Indonesia. Unfortunately, it is surrounded by three active volcanoes which have recently erupted and spewed volcanic ash. Even though volcanic ash movements can be predicted, these events always have the effect of surprises by causing many flight delays or cancellations that lead to enormous economic losses. This occurred because of the lack of preparedness and mitigation plans in dealing with this threat. To overcome this problem, a volcanic ash risk map was generated by combining flight route data, 30 years of wind data in various elevations, rainfall data in a different season, and volcanic ash trajectory data from three surrounding volcanoes namely Mount Raung, Agung, and Rinjani. The result shows that during the easterly wind season the risk of volcanic hazard was higher since the two most active volcanoes (Mount Agung and Rinjani) are located in the eastern part of this airport and during this season there is less rainfall that could wash the ash away. Therefore, appropriate mitigation plans can be established as well as airport collaborative decision making

        Speaker: Mr Kadek Sumaja (Meteorology, Climatology, and Geophysical Agency of Indonesia (BMKG))
      • 50
        Possible Civil and Scientific Application of IMS data Analysis for Volcano Monitoring with DTK-PMCC and Geotool Software

        Everyday waveform data is detected and recorded by the seismic, hydroacoustic and infrasound stations (SHI) of the International Monitoring System produced by different sources coming from the earth, the oceans, and the atmosphere. In this study, signals of interest are the ones from volcanic sources, which can be put to wider civil and scientific use, from helping to save lives in case of major volcanic activity. Most volcanoes generate precursor signals before an eruption such as earthquakes, tremors, swarms, weak explosions, and landslides that SHI stations could record. A proper onset time detection, classification, and location of volcanic signals and with the support of an enormous catalog of event bulletins, crucial time can be gained in the prediction of a potential eruptive scenario and advice the authorities to evacuate the population before the intense lap of activity start. In this work, we will show some examples of SHI volcanic signals that can be analyzed interactively in an efficient way with the help of Geotool and DTK PMCC which are part of the NDC in a box software package, that available to Member States free of charge as part of the technical assistance through the capacity building and training.

        Speaker: Mr Aaron Gutierrez (CTBTO Preparatory Commission)
      • 51
        Infrasound Array Observations of Avalanching Glaciers

        Ice avalanches constitute severe natural hazards, threatening human lives and infrastructures, and are expected to increase with ongoing climate change and population pressure forcing settlements into exposed terrain. In Europe, costly monitoring programs have also highlighted changing glacial hazards. Consequently, monitoring and warning systems, which help mitigate the threat and impact of mass movements are a key component of hazard management in mountainous regions worldwide.
        In this study we show how infrasound arrays are able to detect and locate ice collapses from a glacier front and under specific conditions might allow to provide an estimate of the source volume. This study focuses on small scale (< 10.000 m3) ice collapses as recorded by local (< 2 km far) arrays, and fluid-dynamics based estimates of ice volumes inferred from infrasound are compared with independent measurements to validate theoretical estimates and to define experimental relations.
        These results show how infrasound array observations may provide successfully quantitative information of glacier collapses and ice avalanche volumes, thus opening new perspectives for monitoring avalanching glaciers and providing warning for break-off events.

        Speaker: Mr Giacomo Belli (University of Firenze (UNIFI))
      • 52
        Dating Paleo Tsunamis with Strontium

        The main objective of this project is to be able of identifying Paleo tsunamis and climate change. Using heavy metals deposits and calcium ratio, more specifics strontium. Our islands during time have been affected by a lot of earthquakes, leaving an enormous possibility of being affected by tsunamis, more of them, historically. Using strontium and calcium ratio we will be able to detect where have been places in our cost and season of drought, that have been affected by these kinds of events. All the coastal have been by the influence of tsunamis generating by subduction earthquakes. Since the formation of the island, leaving all of the island shores with sediments, organic materials and heavy metals, the study of this sediments, the detection of this metals. Geochronological dating using strontium and calcium ratio have been used before, for these purpose with a high level of confidence and a low values of standard deviations. This analysis will also leave us the possibility to review our risk analysis in terms of climate events and generate others research in terms of new climate policy form our governments.

        Speaker: Mr Pedro Miguel Paulino Paulino (Centro Nacional de Sismología de Republica Dominicana (CNSS-UASD))
      • 53
        California and Nevada Short Term Seismic Risk Detection

        Old fashion earthquake early warnings are changing in a new era in the shadow of Earthquake Preparedness Alert (EPA), which instead of noticing only a few seconds, issues a few days in advance. Still, EPAs need more efforts for being used in the public sector, but already they are used in oil and gas, mining in California and Nevada. Since September 2020, the generated models in project Earling analyze risk level changes in these two regions. Since then, all the larger than M5 earthquakes were detected a couple of days in advance. For example, Petrolia residents felt shaking of a M 6.2 earthquake on 20 Dec 2021. The earthquake rattled the region three days after the models detected a high risk time window for the region. Based on Federal Emergency Management Agency (FEMA) reports, these two regions experiencing about 85% of the 75,000 annual earthquakes in the US. So low false alert ratio in the regions is mandatory to make decisions based on seismic risk level changes. Whilst Earling marked five high risk time windows in 2021 it didn’t mark any time windows as high risk until the end of November 2022, which means precise risk detection both in avoiding false positive and false negative alerts.

        Speaker: Mr Farzad Azima (Earling Ltd)
      • 54
        The Interconnection Between the Comprehensive Nuclear-Test-Ban Treaty (CTBT) and the Nuclear Non-Proliferation Treaty

        The CTBT is considered to be a global instrument for the enhancement of international peace and security through the banning of nuclear weapons tests and constraining further development of existing nuclear weapons, on the other hand, the Treaty on the Non-Proliferation of Nuclear Weapons (NPT) was established to prevent the proliferation of nuclear science and technology in all its ramifications and advance the peaceful uses initiatives as well as address disarmament by nuclear weapons states. The two treaties are interconnected in that they both offer a foundation for eliminating the spread of nuclear weapons and providing the necessary tools for the promotion of global stability. This widespread benefits of peaceful uses of science are an enormous success of the NPT regime as well as the civil applications of the CTBT within the scope of the International Monitoring System data and International Data Centre products. This work looks at how the CTBT and the NPT are interconnected, particularly the CTBT's link to the decision in 1995 to indefinitely extend the NPT. The 2020 Review Conference on the NPT which took place in August 2022 provided a benchmark to support the entry into force of the Treaty, which is considered the cornerstone of non-proliferation.

        Speaker: Mr Awwal Bisallah (Nigeria Atomic Energy Commission (NAEC))
      • 55
        The CTBTO as a Stakeholder: Action in the 2021-2030 UN Decade of Ocean Science for Sustainable Development

        Data from the IMS hydroacoustic, infrasound and seismic station networks empowers civil and scientific applications in climate knowledge generation and ocean monitoring activities across the world. Meanwhile, the value of science-informed, evidence-based policy making has gained wide recognition for providing robustness, clarity and practicality in driving the global sustainability agenda and management of our natural resources. With the objective of proposing partnerships that can advance entry into force of the CTBT, this project establishes the relevance of the CTBTO as a stakeholder in the UN Decade of Ocean Science ("Ocean Decade"), and how engagement and framework alignment can be envisioned and approached. This will be developed through efforts to 1) Capture the current range of relevant working programmes solicited by the Ocean Decade, 2) Identify pathways to engage and integrate interactions, and 3) Assess possibilities for a collective impact on security and sustainable development. The outcome of this project shows how the CTBTO's expertise in capacity building and interagency coordination can be distinguished and leveraged in this context.

        Speaker: Ms Jovita Ho (CTBTO Youth Group)
    • Side Event - YPN Forum

      Forum

      Session is opened to the public as a first come first served basis until room capacity limit is reached.

      • 56
        Young Professionals Network – SnT 2023 Side Event Forum

        Forum

        The future of the CTBT verification system – opportunities for science and technology
        - Presentation and discussion on gaps in science and technology
        - Challenges - the NDC perspective

        During this side-event we would like to discuss the future of the CTBT verification system. The development and implementation have been ongoing for 26 years, and the system is ninety per cent in place. Seen from a scientific and technological perspective, how do we envision the coming decades?

        A presentation and panel discussion by YPN members and mentors will discuss the opportunities in science and technology to improve the operation and functioning of the verification system. This panel of younger expert will also contribute their views on challenges faced by the system seen from NDCs around the globe.

        Speaker: Mr Jelle Assink (Royal Netherlands Meteorological Institute (KNMI))
    • Lightning talks: P1.2-1, P3.1, P3.4, P4.5 Wintergarten

      Wintergarten

      • 57
        Improvements of the High-Precision Tiltmeter’s Instrumental Complex Installed in the Northern Caucasus Geophysical Observatory of IPE RAS

        During last year a large volume of tasks was made in our high-precision tiltmeter’s instrumental complex installed in the underground geophysical laboratory of IPE RAS situated at deep adit in Andirci mountain not far from of the Elbrus volcano. The main scope of work was devoted both to improving the instrumental park of the laboratory and to carrying out a set of works on precision spatial orientation of geophysical measuring equipment on pedestals in the adit. Now the instrumental complex of laboratory consists of the main unique instruments (a two-axial high-precision tiltmeter and quartz tiltmeter) and the electronic 24 bits data acquisition, processing, and storage systems. There are installed round-the-clock monitoring of the parameters of the environment around the tiltmeters, including precision measurement of the temperature of the ambient air with a relative measurement accuracy of about 0.001 degrees Celsius, the pedestal and body of the tiltmeter, the measurement of humidity and atmospheric pressure. In addition, the highly sensitive and eye-safe LIDAR system is helped to monitor the aerosol emitted by cracks at the installation site of the complex. The achieved orientation of the actual position of the pedestals was made with an accuracy of ±00°02'.

        Speaker: Dr Valentin Gravirov (The Schmidt Institute of Physics of the Earth of the Russian Academy of Sciences (IPE RAS))
      • 58
        High Frequency Ground Motion Calibrations of Seismometers used at IMS Stations

        Calibration of seismometers used in nuclear explosion monitoring systems, such as the International Monitoring System, is important for providing confidence in the measurements of ground motion and the resulting analysis that is performed on the waveform time series data. Six models of seismometers widely used at International Monitoring System stations have been calibrated using high precision vertical and horizontal shake tables that utilize metrologically traceable measurements of instrument motion using a laser vibrometer. The results of these ground motion calibrations are compared to the instruments’ nominal response provided by manufacturers and to their electrical calibration results which are obtained in a similar manner to in-field calibrations. This study focuses on the high frequency (up to 50Hz) performance of the instruments and offers insights into how the instruments perform.

        SNL is managed and operated by NTESS under DOE NNSA contract DE-NA0003525

        Speaker: Mr Doug Bloomquist (Sandia National Laboratories (SNL))
      • 59
        Distributed Acoustic Sensing: A Step Towards the Standardization

        Distributed acoustic sensing (DAS) is experiencing an exponential growth. Although some difficulties in applying this technology to solve some problems of seismology have been encountered, however the main obstacle is insufficient metrological assurance. For each virtual sensor (channel), a lot more work is required in determining its positioning, orientation, transfer function and self-noise, etc. Part of the metrological characteristics can be estimated in advance if you know the type of cable, the depth and method of its laying, the type of soil and its compaction and local conditions. A library of publications on the influence of these parameters on the metrological characteristics is needed. For specifying other characteristics it is possible to develop simplified evaluation methods that, with sufficient accuracy, will allow the use of DAS. Currently, a lot of work is being carried out using DAS, its comparison with traditional seismic sensors and study of individual metrological characteristics. Each such study has an undoubted value, because it adds a new brick to the DAS. In this work, we describe some of the principles and considerations that we used in designing of the experiments.

        Speaker: Konstantin Kislov (Institute of Earthquake Prediction Theory and Mathematical Geophysics (IEPT RAS))
      • 60
        Main VNIIA Focus Areas Related to the CTBT Technologies

        VNIIA is a leading company of Rosatom State Atomic Energy Corporation in CTBT implementation, which currently performs a range of researches:
        - develops a scientific and methodical support and hardware and software for CTBT on-site inspection (OSI) activities, provides a comprehensive assessment and analysis of efficiency of controls and data information content published by the International Data Centre (IDC);
        - participates in the analysis of events which reveal a possible non-compliance with CTBT on the part of other States Parties, collects the geophysical and radionuclide information based on products of the IDC;
        - develops software to process the geophysical information in the National Data Centre;
        - improves the data analytics system to use it in applied researches for monitoring the CTBT compliance;
        - investigates the ways to create an expert system for checking a procedure for CTBT OSI and for using it in applied researches in the framework of the Rosatom activities in the field of CTBT compliance monitoring in order to predict and evaluate OSI results;
        – has finished the development of a short period vertical seismometer and three-component broadband seismometers for the seismic monitoring systems

        Speaker: Mr Gleb Zasimov (All-Russia Research Institute of Automatics named after N.L. Dukhov (VNIIA))
      • 61
        Noise Study Examples for Infrasound Stations

        Recent development in infrasound noise models (Marty et al, 2021) and progress in digitizers’ and microbarometers’ design allows the introduction of precise infrasound noise studies for new installation and for station upgrades. IMS/ED/SA has compiled a library of equipment self noise data and background infrasound noise data of IMS infrasound stations based on percentile calculations. The presented noise study charts show the results of the studies at multiple IMS stations. The outcome suggests revision of the IMS minimum requirements for infrasound station specifications in the part of microbarometer and system noise.

        Speaker: Pavel Martysevich (CTBTO Preparatory Commission)
      • 62
        Spectral Characteristics of Seismic and Infrasound Noise by Data of the Monitoring Network Stations of the National Nuclear Center of the Republic of Kazakhstan

        The spectral characteristics of seismic and infrasound noise were calculated by the waveforms of the NNC RK network stations using PQLX software. The calculation results were compared with the seismic noise model by Peterson and infrasound noise by Brown. The daily and seasonal noise variations were analysed. Special attention was paid to regularities of the level change at microseismic maximum. The observed peculiarities are well explained by the location and dynamics of microseism and microbarom sources located in the North Atlantics.

        Speaker: Yuriy Smirnov (National Nuclear Center of The Republic of Kazakhstan)
      • 63
        Extension of the In Situ Measurement Using the Modular Design Sea Floor Observatory System

        Two oceanic plates are converged offshore around the Japanese Islands, in which the Philippine Sea plate is subducting at the Nankai trough in southwest Japan. Historically, a mega-thrust earthquake is repeated every 100-150 years along the Nankai trough, and the last earthquake series occurred in the 1940s. For this reason, real time sea floor observatories for earthquake and tsunami monitoring, i.e. the DONETs were installed in 2010. The DONET is capable of adding new sensors with plugging in underwater connectors. Making use of this underwater technology, three borehole observatories, two different typed tilt meters, and one fibre-optic strain meter have been connected with the DONET before. In 2022, two fibre-optic strain meters were additionally installed at the same location of the existing fibre-optic strain meter, making it possible to compare to each other and reduce the ambient noise. In this presentation, we introduce the underwater technologies developed for adding new sensors. Such technologies include tools for thin fibre-optic cable extension, plugging in underwater connecters, etc. worked by a remotely operational vehicle (ROV). It has been shown that our in situ measurement can be performed based on the modular design sea floor observatory system and supported by advanced ROV operations.

        Speaker: Mr Hiroyuki Matsumoto (Japan Agency for Marine-Earth Science and Technology (JAMSTEC))
      • 64
        Integration of an Optical Based Sensor in a Mechanical Seismometer

        In this research, a new optical sensor is used to measure the suspended mass displacement in the seismometer. In the last decades, scientists have used optical interferometer set-up to improve accuracy in displacement measurement. To integrate such optical measurement in a seismometer, all the optical functions, as beam splitter, are integrated in an optical substrate. The only remaining macroscopic elements are the mirror fixed on the suspended mass and the lens to focus the beam on the mirror. The intrinsic noise is below the seismic low noise model all over the bandwidth of interest. To correct the measures from optical defects of the lens or/and the mirror, a correction algorithm is used and allows to reach a coherence of one between the optical measurement and traditional sensors. The results show the accuracy and reliability of such optical sensor integrated in a mechanical seismometer.

        Speaker: Olivier Rousseau (Commissariat à l’énergie atomique et aux énergies alternatives (CEA))
      • 65
        Design and Validation of a Wide Band Optical Seismometer

        Our recent research in an integrated optical interferometer has led to the development of a very low noise optical seismometer based on such transducer. The performances of the transducer combined with the appropriate technical choices for its integration leads to a seismometer which is able to measure subnanometrics earth displacements over a very wide bandwidth. Our optical seimometer has an intrinsic noise which is at least 10 dB below the seismic low noise model from 10-5 Hz up to 10 Hz. More generally, this seismometer benefits from more than 50 years of experience in geophysic sensors design at CEA.

        Speaker: Mr Fabrice Lepoint (Commissariat à l’énergie atomique et aux énergies alternatives (CEA))
      • 66
        Preliminary Design of Relative Humidity Virtual Sensor in Northern Middle Java Province of Indonesia

        Relative humidity sensor is one of automatic weather station (AWS) component. Based on annual quality control, relative humidity sensor data have approximately 7% of unavailability because of system maintenance in 2020. This study proposes design of relative humidity virtual sensor according to competitive sensing concept. It is simulated on three AWS in northern Middle Java Province of Indonesia, namely AWS Kandeman, Pemalang and Kajen from January to March 2021. These AWS are installed adjacently around northern highway of Java in triangular constellation. Virtual sensor is arranged based on data fusions from physical sensors using MLP and LSTM algorithm. Three previous delayed temperature and relative humidity sensor data is utilized as inputs. Data are then segmented into 70% training and 30% testing data. Virtual relative humidity sensor for AWS Kajen is accurately composed by combination of delayed AWS Kandeman and Kajen data using MLP with 1.38 %RH of RMSE. Virtual relative humidity sensor for AWS Pemalang is accurately composed by combination of delayed AWS Kandeman and Pemalang data using MLP with 2.04 %RH of RMSE. Virtual relative humidity sensor for AWS Kandeman is accurately composed by combination of delayed all of those AWS data using MLP with 2.04 %RH of RMSE.

        Speaker: Mr Haryas Wicaksana (Meteorology, Climatology, and Geophysical Agency of Indonesia (BMKG))
      • 67
        On the Influence of Atmospheric Conditions on Ambient Seismic Noise

        Ambient seismic noise (ASN) is defined as small vibrations recorded throughout the Earth’s surface. The generating noise sources are classified into anthropogenic sources (<1 s) and natural sources (>1 s). In this study, we used data from the Romanian Seismic Network (RSN) stations, operated by the National Institute for Earth Physics (NIEP) and we analysed the influence of atmospheric parameters on the ASN level. A long term evolution of seismic noise emphasized a drop-off in the noise level in 1-2 s period band interval at most of RSN broadband stations in the second half of October 2019. We also observed a good correlation between the increase of the noise level and the increase of the wind speed for the 0.5-0.05 s period band interval. In this paper, the atmospheric data are provided by the NIEP’s weather stations collocated with seismic stations.

        Speaker: Andreea Tolea (National Institute for Earth Physics (NIEP))
      • 68
        A Truly Very Broadband (VBB) Borehole Seismometer with flat Response over five Decades of Frequency

        Decades ago new opportunities in seismology were opened by the development of broadband seismic sensors with feedback. The three defining characteristics of these instruments were the bandwidth extension to longer periods, a much lower intrinsic noise and a higher dynamic range. However, the goal of further extending their bandwidth to frequencies above 100 Hz has proven elusive because these sensors are plagued by parasitic resonances leading to modes not controllable by the feedback system. Here we present a new low noise seismic borehole sensor with a truly VBB flat response over five frequency decades from 2.7 mHz (360 sec) to 270 Hz. The instrument has no mechanical resonances below 400 Hz. We achieved the bandwidth extension to high frequencies with improvements of the mechanical design, i.e. the arrangement of the pivots and the geometry of the spring. The design is realized in a borehole arrangement, where three sensors are stacked in 90-degree angles to each other. Including a single jaw hole-lock as a clamping mechanism the complete stack has a diameter of 89 mm, is 625 mm long and weighs about 24.5 kg. We show test results from three co-located complete borehole sensors with identical frequency responses.

        Speaker: Cansun Guralp (Gaiacode Ltd)
      • 69
        Challenges of Low Frequency Seismometer Calibrations

        The traceable calibration of seismometers is research work within the European research project (InfraAUV), which is part of the EMPIR programme. In this project, novel in-laboratory and on-site calibration procedures for seismometers are developed. The in-laboratory calibrations are carried out using electrodynamic shakers to excite sinusoidal vibrations. These excitations are measured by the seismometer under test and a reference laser interferometer. The calibration process itself is already well-established, used with accelerometers and standardized in ISO 16063-11. However, several specialties of seismometers require consideration: 1) Frequency range and duration: the low frequencies (here, as low as 10 mHz) require a long measuring time. To reduce the time consuming and costly measurements, excitation methods with multiple frequencies have been developed and applied to seismometers; 2) Tilting: the high sensitivity of seismometers makes horizontal calibrations prone to deviations from tilt. The tilting results in components of the gravitational acceleration adding to the velocity signal generated by the exciter. If the tilting changes proportionally to excitation, it has the same frequency and phase as the excitation; 3) Electromagnetic disturbance:
        some seismometers are sensitive to magnetic fields. Electrodynamic shakers produce inhomogeneous static and dynamic magnetic fields. Both can negatively affect the measurement result.

      • 71
        An External Calibrator for Hyperion Infrasound Sensors: Progress and Direction

        Hyperion Technology Group, Inc., along with the National Center for Physical Acoustics at the University of Mississippi, USA (NCPA ), has been developing an integrated calibration system for its line of infrasound sensors. This technology will allow self-calibration of the infrasound sensor in the field using existing installed equipment. While currently verified as an add-on for existing sensors, work is progressing to integrate the system into the sensor hardware for a fully self-contained deployment. The calibrator allows the sensor to function nominally without significant change in response. When activated by an external signal from existing digitizers the system will produce signals between 0.01 and 10 Hz at amplitudes greater than 30 Pa. We report on the theory, performance, and roadmap for implementation.

        Speaker: Mr David Harris (Hyperion Technology Group Inc.)
      • 72
        Compact Dual Fabry-Perot Refractometer for Infrasound Dynamic Pressure Measurements

        This poster presents the recent development and preliminary results of a compact laser refractometer based on a dual Fabry-Perot scheme at 1550 nm for dynamic infrasound pressure measurements. The measurement of the beat frequency between two lasers slaved to two Fabry-Perot cavities allows to follow the variation of the refractive index of the air, and thus to estimate the pressure inside the measuring cavity. Associated with a dynamic infrasound pressure generator developed at CEA, the generated pressure variation, controlled and repeatable, is directly printed on the measured beat frequency and compared to infrasound sensors. The main objective of this work is to demonstrate the capabilities of a compact laser refractometer whose simple and unique design has been adapted from static absolute pressure measurements to dynamic infrasound pressure measurements. The resulting sensor has demonstrated its ability to measure dynamic pressure over the entire infrasound frequency band, with excellent performance. Further studies on the specific shape of the frequency response are underway to evaluate the discrepancy between the measurements and the model, and to assess its uncertainty budget.

        Speaker: Dr Paul Vincent (Commissariat à l’énergie atomique et aux énergies alternatives (CEA))
      • 73
        Observations of Natural and Induced Seismic Events and Monitoring of the Nuclear Underground Depository Using Slim Borehole Adapted SIA Sensors

        Over the past five years ASIR has adapted silicon audio (SiA) interferometer based sensors in our borehole broadband seismometer, model ASIR ABB, for making seismic observations in ~100 to 1000 m deep slim boreholes. The shifts are used to rapidly and accurately control a force-feedback circuit. The current ~60 mm outer diameter triaxial SiA sonde has been installed in drill hole with inner diameters as small as 76 mm and tilts with 15d.These sensors have a 3 dB frequency-response bandwidth of 120 sec to 1300 Hz, a clip level of +0.5 g, and a dynamic range of 172 dB. During a rapid, long tilt event, sensor settles with a 60s long exponential decay. Ranging from a plate boundary to an underground mine, and a subsidence site, these sensors have returned complete seismograms for nearby events ranging in size from M < -1.5 to M> 4.5. The SiA sonde’s ~1-10 s seismic event spectrum is well above background noise. At the plate boundary, the borehole SiA improved event detection over the local surface net by as much as one unit in magnitude.

        ASIR ABBT (with Thermal probe) broadband seismometer is successfully used for micro seismic monitoring of the nuclear underground depository in Europe.

        Speaker: Dr Leonid Zimakov (Advanced Seismic Instrumentation and Research LLC (ASIR))
      • 74
        Progress of Science Monitoring And Reliable Telecommunications Subsea Cables for Observing the Oceans and Earth

        The Joint Task Force for Science Monitoring And Reliable Telecommunications (SMART) Subsea Cables is working to integrate environmental sensors (temperature, pressure, seismic acceleration) into submarine telecommunications cables. This will support climate and ocean observation, sea level monitoring, observations of Earth structure, tsunami and earthquake early warning and disaster risk reduction. We present an overview of the initiative and a description of ongoing projects, including: the InSea wet demonstration project off Sicily; the CAM ring system connecting the Portuguese mainland, Azores and Madeira (funded); progress towards installation of a cable connecting Vanuatu and New Caledonia; cable plans between islands of Indonesia; a planned cable from New Zealand to the Chatham Islands; a plan for a cable connecting Antarctica to New Zealand, and; a project to connect Europe and Japan via the northwest passage (Far North Fiber). These SMART systems are the initial steps to global implementation and will be influential in the final standards and policies that evolve. In addition to the diverse scientific and societal benefits, the telecommunications industry mission of societal connectivity will also benefit because environmental awareness improves both individual cable system integrity and the resilience of the overall global communications network.

        Speaker: Dr Bruce Howe (University of Hawaii at Manoa)
      • 75
        Temperature Dependence of Frequency Response of Short Period Seismometers

        Short period seismometers were the workhorse of the World-Wide Standardized Seismograph Network built in the 1960s. Because they have very low noise in the band of interest for array seismology, they continue to be used in arrays throughout the International Monitoring System (IMS) of the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO). In an earlier study, we used single frequency calibrations to validate a model that predicted the temperature sensitivity of the sensors used at the Yellowknife seismic array (YKA) to be -0.16%/°C. Given that seasonal temperature swings can exceed 50°C in a place like Yellowknife, the effect on sensor gain can be significant. Here we perform broadband calibrations to validate a model of the temperature dependence of the transfer function of the short period sensor. The model predicts the temperature dependence of the damping to be -0.14%/°C. We show how the temperature sensitivity of the damping results in a predictable seasonal dependence of the instrument gain and phase near 1 Hz. We recommend changes to the nominal response of the sensors in the YKA array, as well as routine broadband calibration of seismometers to detect similarly subtle effects which might impede the performance of the IMS.

        Speaker: Nick Ackerley (Canadian Hazards Information Service (CHIS), Natural Resources Canada (NRCan))
      • 76
        CalxPy: A Software for Calibration Against a Reference

        The International Monitoring Systems (IMS) draft operational manuals for waveform stations require that IMS stations be calibrated regularly. Since 2012, the Provisional Technical Secretariat (PTS) had relied mostly on electrical calibration to meet that requirement. However electrical calibration has inherent challenges (no traceability, integration and sustainment issues, high operating costs, etc.). A part of the geophysical community, including station operators, has started performing regular calibrations by comparison against a co-located reference. This method allows a more systematic and centralized approach to calibration. Over the past few years, it has been increasingly used at IMS stations, particularly infrasound ones. In this context, the PTS is developing tools to support this alternative approach. We present CalxPy, a web-application developed at the PTS for the calibration of geophysical systems by comparison. With CalxPy, one can calculate, store, and display the response of a system for a given period, or track the evolution of the response against time or environmental variables. CalxPy allows the reporting of calibration results in IMS2.0 format. CalxPy supports the Initial calibration and on-site yearly calibration processes, as well as data quality control. CalxPy can be deployed in the IDC pipeline and in NDC-in-a-box.

        Speaker: Benoit Doury (CTBTO Preparatory Commission)
      • 77
        Refining Event Parameters in Geotool Using Non-International Monitoring System Stations

        Version 3 of Geotool (aka GeotoolQt) provides a powerful, easy to use interface with data import facilities for International Monitoring System(IMS) and non-IMS stations. IMS-related information, including parameters of events and arrivals, as well as waveform data, can be imported directly from VDMS while non-IMS information can be directly retrieved from FDSN web services, including but not limited to IRIS and GFZ. We demonstrate these new features based on a use case where a reviewed Event Bulletin (REB) event and its related data is imported from VDMS. Additional waveform data of non-IMS stations are retrieved from GFZ. The REB event parameters (location, magnitude, gap etc.) are then refined with the additional arrivals on the non-IMS stations resulting in an improved event location and reduced error ellipse.

        Speaker: Wolfgang Sommerer (CTBTO Preparatory Commission)
      • 78
        Development of Software Simulation Pipeline for High Resolution Atmospheric Transport Modelling

        The Flexpart Atmospheric Transport Model (ATM) is traditionally driven by ECMWF and GFS meteorological model inputs.  Flexpart-WRF is a variant of the standard model that accepts a wide range of Weather Research and Forecasting model (WRF)-generated meteorological inputs to support very high resolution simulations over customized domains. The chain of activities needed to produce custom meteorology files from WRF and make them available to Flexpart-WRF for a successful simulation is complex and prone to failure for a number of reasons, and the work described here is aimed at packaging all of the complexity into an easy-to-use system. Building on the experiences gained from an exploratory prototype system built several years ago, this Enhanced High Resolution Atmospheric Transport Model (EHRATM) system is being developed in a Python-driven environment to support simulations ranging from relatively simple and straightforward, to complex simulations with special requirements. Adopting the philosophy of some other well-known Python packages, our goal is to “make easy things easy and hard things possible.”  This work is ongoing, and the presentation will describe a detailed overview of the project and its current status.

        Speaker: Mr Donald Morton (Boreal Scientific Computing)
      • 79
        Synergy Between Comprehensive Nuclear-Test-Ban Treaty Technologies and National Technical Means

        The International Monitoring System (IMS) of the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) is designed to detect nuclear explosions with a minimum yield of one kiloton of TNT equivalent worldwide. The IMS uses four verification technologies - seismic, Infrasound, hydroacoustic and radionuclide - in a synergistic manner to enable the detection, location, and identification of potential nuclear explosions. Each of these technologies has advantages and limitations, and overcoming these limitations is crucial for the verification regime and for the civil and scientific applications of IMS data and International Data Centre (IDC) products. This poster will demonstrate the use of multi-technology fusion between the four technologies and other national technical means, such as satellite imagery, to overcome gaps and limitations through examples of events in Tunisia (quarries and mines), where infrasound and seismic data is used to distinguish sources in areas with a low seismic network coverage. Another example is using infrasound and satellite imagery during Stromboli eruptions, where other forms of synergy will be explained. The poster will highlight how classic synergy and other forms of synergy between technologies can fill gaps and improve results by utilizing the strengths of each technology while overcoming its limitations.

        Speaker: Ms Mariem Agrebi (Vienna University)
      • 80
        Expert Technical Analysis Case Study: 2019 National Data Centre Preparedness Exercise Trigger Event

        The trigger for the 2019 National Data Centre Preparedness Exercise (NPE) scenario (a fictitious nuclear explosion) was based on a real ML 3.7 shallow tectonic seismic event within an earthquake swarm in southern Germany, near the city of Constance. The event occurred at 23:17 UTC on the 29 July 2019 (e.g. see International Seismological Centre bulletin) and is not found in the International Data Centre (IDC) standard products (Reviewed Event Bulletin and Standard Event List 3) or the Late Event Bulletin, even though eight International Monitoring System (IMS) seismic stations are within 1500 km of the event and the IDC threshold monitoring detection capability for this period suggests it should be detected. However, this event was clearly observed at IMS stations in Switzerland (DAVOX), Germany (GERES), Czech Republic (VRAC) and the UK (EKA), as well as at numerous non-IMS stations across Europe. An event was formed by the NET-VISA algorithm and listed in the IDC NET-VISA database ("vSEL3"). We re-analyse the NPE 2019 trigger event (and selected others in this swarm of earthquakes) using both IMS and non-IMS stations and demonstrate the potential important role of auxiliary IMS seismic stations and local seismic networks as part of the expert technical analysis.

        Speaker: Stuart Nippress (Atomic Weapons Establishment (AWE) Blacknest)
      • 81
        The CTBTO International Data Centre – Snapshot 2023

        The International Monitoring System (IMS), the International Data Centre (IDC) and the on-site inspection (OSI) are the technical elements of the CTBT verification regime (CTBT Art. IV); these are designed to detect any nuclear explosion anywhere (underground, under water or in the atmosphere) and to investigate any findings associated with its occurrence. The role of the IDC is to operate the IMS, receive, collect, analyse, report-on and archive the data; furthermore, to apply on a routine basis, automatic and manual data processing in order to produce and archive standard IDC products on behalf of all States Parties (these are provided to all at no cost) without prejudice to final judgments with regard to the nature of any event, which shall remain the responsibility of the States Parties. This poster gives a portrait of the construction of the IDC, obtained by the Provisional Technical Secretariat since the approval by States Signatories on the restructuring of the IMS and IDC Divisions.

        Speaker: Mario Villagran-Herrera (CTBTO Preparatory Commission)
      • 82
        InSAR Satellite Data – Application for Earthquake Deformations in the Balkan Peninsula

        The use of synthetic aperture radar (SAR) data is a powerful and well established method for remote sensing that enables high resolution measurement of important geophysical parameters such as surface topography, deformation or subsidence of the surface as a result of various processes (earthquakes, tectonic activity, movements of glaciers, mining activity, etc.). The present study illustrates the InSAR technique applied for recent M6+ earthquakes in the region of south-east Europe including Greece and Turkey. Data from both Sentinel-1A and -1B is used. This constellation shares the same orbit plane and include C band imaging operating in four exclusive imaging modes with different resolution (down to 5 m). As a results interferograms and deformation maps are build using SNAP and ArcGIS software. For each deformation map a profile plot of the displacement is depicted. The obtained results can be used in the evaluation of the earthquake deformations supplemented with geological and geophysical information.

        Acknowledgements: This study is conducted within project “Analysis of seismic sources using InSAR satellite data for the Balkan Peninsula region” funded by the National Scientific Program “Young Scientists and Postdoc-2", 2022 by Ministry of Education and Science of Republic of Bulgaria.

        Speaker: Lyuba Dimova (Sofia University "St. Kliment Ohridski")
      • 83
        The Comprehensive Nuclear-Test-Ban Treaty Protocol: Possible Hindrance for On-Site Inspection Obligations

        Compared to many other Treaties and international conventions, one of the unique and in-built characters of the Comprehensive Nuclear-Test-Ban Treaty is its Protocol. Considering the sensitivity that is required to address the verification regime, having limitations and even restrictions on matters pertaining to national security is understandable. Yet, listing the tools as a part of the Protocol is having a negative impact particularly on on-site inspection (OSI) functions, as accommodation of novel technologies is discouraged. The “National Technical Means (NTM)” might bridge the gap between the advanced technologies and listed stalled tools of the Protocol. The NTM could serves well in the planning stage of the OSI as the waveform analysis of the verification regime (International Monitoring System) could be integrated with NTM inputs. However, once the inspection is initiated the inspected State Party (ISP) could limit the NTM information flow and most importantly the inspection team has to rely on the outdated tools provided in the Protocol for the OSI inspection. Maintaining the balance between the successes of OSI objectives while securing national interests, the States Parties shall identify an agreeable solution towards upgrading OSI tools in par with the technological advancement.

        Speaker: Mr Nalin de Silva (Geological Survey and Mines Bureau)
      • 84
        Impact on On-Site Inspection Efficiency due to Lack of Team Building Opportunities

        Despite remote waveform analysis and nuclear signatures, an on-site inspection (OSI) remains as the final verification regime for potential indicatives of ambiguous events of CTBT violation(s), which is designed to produce conclusive evidence. As the potential violator, the inspected State Party is accustomed to the procedures and tools available to the OSI, the success of an inspection depends on intuition and out-of-the box thinking by the inspection team. In most cases the scenarios that an inspection team has to address could not be foreseen, hence, critical thinking and prompt actions produces fruitful results of the inspection. As “unexpected” is the norm of such inspection, synergy of observations and knowledge of inspectors has a paramount importance towards fulfilling the OSI task.

        COVID-19 situation made remote training of OSI tools and procedures mandatory, driving the Inspectorate towards semi-automatic mode providing limited opportunities for team-building, while hardly having sufficient room for diversified sentiments. Previous Integrate Field Exercises (IFE) reveals the importance of having well-coordinated closely-bounded team, with a space for constructive personal initiatives bringing into ever evolving on-field inspection progression. The OSI regime shall implement process to assess the quality of remote training compared to in-house team-building and need to device a cost-effective mechanism filling the gaps, accordingly.

        Speaker: Mr Nalin de Silva (Geological Survey and Mines Bureau)
      • 85
        Radiation Health and Safety Solution for Inspection Teams

        In practical scenarios, on-site inspection (OSI) could be conducted in a place of nowhere which is in an environment with radiation hazards. Both OSI training courses and Integrated Field Exercises should take into full consideration such conditions, so as to build up the inspection team's operational capacity for real cases. From the perspective of inspection team functionality and inspection team health and safety, besides suitable radiation protection solution for inspection team members, radiation hazards prevention solution should take into consideration not only the radiation monitoring of inspection team members in real time, checking the radiation level of inspection team members at the base of operations (BOO) when they are coming back from the inspection area, but also the checking of the radiation level of OSI equipment. This work would carry out a systematic solution to radiation monitoring both of the inspection team members and OSI equipment. Equipment includes radiation protection suits, wristband dosimeter for inspection team members, hands and feet radiation checking equipment, whole body radiation checking equipment at BOO and radiation checking equipment for inspection equipment and support vehicles.

        Speaker: Mrs Jing Yang (HOPE Investment Development Co. Ltd.)
      • 86
        Interagency Cooperation Based Global Navigation Satellite Systems Solution to On-Site Inspection

        The International Committee on Global Navigation Satellite Systems (ICG), as an international multilateral platform under the United Nations Outer Space Agency (UNOOSA ), is promoting voluntary cooperation on matters of mutual interest related to civil satellite based positioning, navigation, timing, and value added services. At the same time, the On-Site Inspection (OSI) Division of CTBTO, as the neighbour of UNOOSA, is developing its essential Global Navigation Satellite Systems (GNSS) positioning and navigation equipment for on-site inspection. As a matter of fact, GNSS positioning and navigation equipment is still a classification of equipment whose application to OSI is still a pending issue in Working Group B and policy making organs of the Comprehensive Nuclear-Test-Ban Treaty Organization. This work would propose a 4-mode GNSS positioning and navigation solution to OSI, which would involve interagency efforts and all the four major United Ntions declared global satellite navigation systems, including GPS, GLONASS, GALELIO, and BEIDOU. This solution is based on the ICG suggestion of compatibility, interoperability, and transparency among all the GNSS systems. It would not only provide a more reliable and practical solution to in-field OSI positioning and navigation, but also take into consideration keeping the balance between technical sufficiency and practical feasibility.

        Speaker: Mr Yong Sun (Space Star Technology Co. Ltd.)
      • 87
        On-Site Inspection in a Mountainous Environment: Lessons from a Recent Field Test

        The conduct of an on-site inspection (OSI) in an area other than flat has been considered as an additional challenge to the intrinsically demanding characteristics of such a mission. An effort has been made in the past by the Provisional Technical Secretariat (PTS) to identify those difficulties that are particular to the conduct of an OSI in a mountainous environment and to develop appropriate solutions, but always as part of theoretical exercises. The Field Test of geophysical techniques for the detection of deep observables conducted in the Austrian Ybbstal Alps in September 2022 represented the first OSI field activity ever conducted in a pure alpine environment. The Field Test served to understand the current capabilities of the PTS to solve the technical and operational issues faced in such an arduous setting. This paper lists the challenges encountered during the planning and execution of the Field Test, describes the actions taken to mitigate them, and identifies lessons to be learned for the successful conduct of future OSI activities in mountainous areas.

        Speaker: Mr Luis Gaya Pique (CTBTO Preparatory Commission)
      • 88
        Update on Tools to Support On-Site Inspection Equipment Calibration, Maintenance and Protection

        To meet the requirement to certify that on-site inspection (OSI) deployed equipment has been calibrated, maintained and protected, as mandated by paragraphs 38 and 39 of Part II of the Protocol to the CTBT, the Provisional Technical Secretariat (PTS) has introduced a number of supporting tools. This paper highlights initiatives to protect equipment and those used to support and record the maintenance and calibration of equipment. The system for maintaining and managing OSI equipment and software, EIMO, is now used on a daily basis, facilitating work at the CTBTO TeST Centre, where it is used as the central database for all OSI deployable equipment. The custom browser based application has been further expanded with the creation of new instances: a training instance for capacity building and another for the testing and development of new functionalities. Among the new features reported in this paper is the introduction of RFID tags and checks, which represent an important milestone required for the protection of equipment. To further protect deployable equipment, storage containers now have individual locks with keys stored in a two-factor authentication key cabinet, with access assigned on a key by key basis. Similar access control is also being considered for use during OSI deployment.

        Speakers: Aled Rowlands (CTBTO Preparatory Commission), Remi Colbalchini (CTBTO Preparatory Commission)
      • 89
        On-Site Inspection: Inspected State Party Perspectives Towards Successful Inspection

        The behavior of the inspected State Party (ISP) is one of the elements that has not been adequately analysed in an on-site inspection (OSI), though the same has a grave impact on the inspection. Generally, three distinct common scenarios lead to a request for a review: ambiguous natural events that associate with partial nuclear emission, nuclear accident and a violation of the Treaty via a nuclear test. In these three instances, the ISP reaction and the behaviors would be very different; close cooperation is expected in the first event as both ISP and the inspection team are driven towards the common objective of assessing the cause of the incident. A partial concealment is expected in the second scenario, particularly driven by “national pride”. The third situation, if occurs once the Treaty enters into force, the behaviors of the ISP would be very different with a minimum degree of cooperation. In such a situation, the ISP is destined to disturb the inspection while adhering to the minimum Treaty obligations. Inspection team engagement with the ISP shall be trained and practiced for distinct, yet common scenarios for an effective inspection.

        Speaker: Mr Nalin de Silva (Geological Survey and Mines Bureau)
      • 90
        An Overview of Inspection Team Functionality and Field Team Functionality

        An on-site inspection (OSI) is a complex forensic investigation that requires a systematic approach that considers the operational, technical and time constraints specified in the Treaty. The information led inspection team functionality (ITF) and field team functionality (FTF) are comprehensive and systematic concepts that serve as essential guidance for the inspection team to conduct its missions during an OSI. This poster visualizes the ITF/FTF concept as three operational cycles: logic cycle, decision cycle and operation cycle. It illustrates how the concepts run and guide the inspection team's daily inspection activities.

        Speaker: Mr Feihong Kuang (CTBTO Preparatory Commission)
      • 91
        Projection System for the On-Site Inspection Airborne Simulator

        The airborne simulator, used to develop and test on-site inspection (OSI) airborne equipment configurations as well as train surrogate inspectors, is being upgraded to provide more realistic training opportunities. The simulator, a converted Mi-2 airframe, now features adjustable window panels and is being supplemented with a projection system that will provide real world views of the terrain. The projection system, once fully implemented, will be comprised of a surface that extends in an arc from the nose of the airframe to the rear most window of the fuselage onto which real world views are projected. The projection and flight parameters will be controlled by the session tutor via a computer. Trainers will also be able to preload flight lines with information including, speed, banking angle during turn etc., and alter flight parameters in real time e.g. speed, pitch, roll and yaw. The project, due for completion in 2023, will provide an enhanced training experience with realistic views of the terrain at flying heights of 100 to 1500 metres above the ground.

        Speaker: Aled Rowlands (CTBTO Preparatory Commission)
      • 92
        Development of Software Tools to Support Operations at the On-Site Inspection Field Laboratory

        As part of the GIMO software platform, developed to facilitate the implementation of on-site inspection (OSI) search logic, specific applications have been developed to meet the requirements of the on-site field laboratory. Broadly, these provide a framework and tools to meet the requirements of environmental sample chain of custody, and sample management in the laboratory including sample measurement and analysis. The architecture used as a basis for field laboratory applications development, deployment and operation are summarized. Data security considerations are highlighted, with particular emphasis placed on the development of a ‘kiosk’ application for the laboratory chain of custody tablet, which restricts access to the relevant chain of custody application only. The workflow, together with the tools developed to facilitate the receipt of an environmental sample in the laboratory, its storage, measurement and analysis are presented. Interactions between the GIMO field laboratory application, measurement systems and analysis software ONIAB are highlighted. This paper also addresses the means by which reports generated for a sample are moved to the ‘receiving area’, reviewed and classified, associated with sample id and then transferred to the relevant ‘receiving area’ based on classification status and then on to the ‘working area’.

        Speakers: Jonetta Ng (CTBTO Preparatory Commission), Aled Rowlands (CTBTO Preparatory Commission)
      • 93
        Potential Application of Wallet Card for Radiation Zones to Inspection Team Health and Safety Protection in Inspection Areas

        According to Iraqi Radiation Law No. 99 of 1980, the Radiation Protection Center (RPC) is a regulatory body in Iraq responsible for monitoring radiation workers. This is done by providing them with personal dosimetry TLD, ED, monitoring Iraqi environment (soil, water, air) and gamma radiation monitoring. For their health and safety we prepared and designed the wallet card to maintain the radiation doses of an inspection team on-site within ALARA principle to reduce the potential doses of radiation and radioactive materials. The wallet card includes: zone, radiation field, contamination and control and with values for each one (i.e. background, safe, low, medium and very high ). All values are according to the instructions of the IAEA. This wallet card is very important for the inspection team in the inspection area because if a zone is very high (>10 mSv/hr ) that needs pre-work planning; pre-work planning; ALARA controls; health and safety team in the inspection area TL, approval: written work plan and Director General authorization. Also the wallet card supplied by RPC to inspectors in radiological emergencies as the RPC is a member of National Emergency Committee, in Iraq with other ministries which are MOST, Health, Defense, etc.

        Speaker: Ms Salwa Al-Salhy (Radiation Protection Center, Ministry of Environment)
      • 94
        Comparative Analysis of On-site Inspection Training Programmes and Methods

        Conducting an on-site inspection (OSI) requires a large variety of resources, i.e. human, financial, technical, etc. The preparation of human resources is a challenge due to the disciplinary diversity of equipment and procedures used. The design of a training programme for future surrogate inspectors is an important task because the human factor largely determines the effectiveness and success of the OSI. The goal of this work was to assess the effectiveness of the OSI Training Programme through a comparative analysis of applied approaches and their interrelationships. The comparative evaluation of online and on-site training methods was done based on six criteria: flexibility, practical skills training, theoretical knowledge, and training capacity. The weaknesses and strengths of each training method were identified. A new training concept including optimization of used methods was proposed, resulting in a 10–15% improvement in the effectiveness of the entire training programme on average. New ways of online learning and its integration with on-site courses were presented. The Kirkpatrick model and the results of the first in-field operation support refresher course were used to conduct a preliminary evaluation of the new OSI training programme, which demonstrated the concept's effectiveness and cost efficiency.

        Speaker: Mr Franz Ontal (CTBTO Preparatory Commission)
      • 95
        Estimation of Mantle Transition Zone Seismic Discontinuities Beneath Northwestern South America from P wave Receiver Function Analysis.

        Mantle transition zone is delimited by two seismic discontinuities at 410 km and 660 km. These are imaged under the northwestern corner of South America using the receiver function technique and a seismological record with up to 30 years registered by the national seismological network of Colombia. Significant variations and spatially systematic in the discontinuity depths were observed. The mean depths for the mantle transition limits are 412±5.3 and 671±5.9 with a mean thickness of 258±6.5, this value is similar to the global average. The low correlation between the discontinuities is caused by the significant depth variation and the thicker mantle transition zone in some areas is because the Nazca and Caribe plates subduction under South America plate. On the other hand, mantle transition zone thinning beneath the Nazca plate possible is due to the Malpelo ridge presence. These observations together with seismic tomography investigations could confirm the interaction of Nazca and Caribe plate within the upper mantle and mantle transition zone hydration.

        Speakers: Jorge Enrique Cubillos Gordillo (Universidad Nacional de Colombia), Carlos Alberto Vargas (Universidad Nacional de Colombia)
      • 96
        Understanding the Earthquake Occurrences and Looking for the Future in South Central Tibet (SCT) Himalaya

        Various seismic precursors are known to be preceded small to large earthquakes. These pre-earthquake signatures which may continue to several months and/years would be employed for earthquake forecasting. In the present investigation precursory seismicity patterns were discussed and used for the identification of precursory swarm to forecast the location of future earthquake in the South Central Tibet Region (SCT) Himalaya. The seismicity data compiled from various catalogues for the period 1963-2006 with mb ≥4.1, have been used to understand the occurrence of three medium size earthquakes sequence 1996 (mb 5.9), 1998 (mb 5.8) and 2004–2005 (mb 6.2, 6.3). Analysis indicates that these earthquakes were preceded by well-defined patterns of precursory swarms and seismicity varies as low-high-low phases in episodic manner. We found two anomalous seismicity patterns having similar spatial and temporal distributions separated by about 15 month’s duration during January 2002-February 2003 and June-August 2004 in the same area but without a mainshock till 2007? Based on analyses of above three events occurrence mechanism and spatio-temporal and focal depth patterns during 2002-2003 and 2004 a localized area (29.6o-30.1o N, 87.7o-88.1oE), could be a potential zone for impending medium size earthquake (M≥6.0) in depth range 25 ± 15 km.

        Speaker: Daya Shanker (Indian Institute of Technology Roorkee)
      • 97
        The Central Part of Madagascar Volcanism Reactivation Possibility

        Madagascar has never experienced any volcanism activity. The volcanisms dated from the cretaceous period are almost all around the coastal zones and Cenozoic at the central part and in the north. Seismically, the central part is the most active. An ancient crater even had smoke from the inside slope. The laboratory of Seismology and Infrasound at the IOGA uses the national seismic stations network to monitor earthquakes and tsunamis. The CTBTO station, OPO, has an important place for monitoring earthquakes in the area. Many seismic crises are recorded from the central volcanic areas and this station is well placed to get better detection. To study the volcanism of the central part of Madagascar, we consider the observations in site, the earthquakes history and a 3-D tomography of the lithosphere. Even though Madagascar has had no volcanic activity for millions of years, the instability of the lithosphere presents the possibility of reactivation of the recent Cenozoic volcanoes is supported by the tomography results.

        Speaker: Mr Ramarolahy Rina Andrianasolo (Institute and Observatory of Geophysics of Antananarivo (IOGA))
      • 98
        Seismic Hazard Studies in Sub-Saharan Africa Using Integrated Techniques

        Seismic hazard assessments (SHA) have not been conducted in large parts of Sub-Saharan Africa (SSA) due to incomplete earthquake catalogues, sparse seismic networks, etc. raising concerns on needed information for planning and disaster risk management. The aim of this study is to bridge the research gap using modern techniques for across the board SHA. Updated catalogue from local networks, CTBTO's National Data Centres, International Seismological Centre and publications spanning 1615-2022 with threshold and maximum moment magnitudes (Mw) of 4.0 and 6.8 formed the dataset. The catalogue, which was declustered and harmonized to Mw, was used with available geological data to delineate area source zones and computation of earthquake recurrence parameters. Four ground motion prediction equations for tectonically similar regions to SSA were implemented using logic tree formalism in the calculation, with all equations weighted equally. With a 1-1000 year period considered, the computed Gutenberg-Richter b-value, activity rates, and regional maximum possible magnitudes ranged from 0.69 to 1.0, 1.6 to 2.1, and 5.2 to 7.2 respectively. Peak ground accelerations ranged from 0.02g to 0.2g for a 10% chance of exceedance in 50 years and seismic hazard maps for 0.1s, 0.2.s, 0.3s, 0.5s, and 0.15s periods were produced. Results are expected to make significant contribution to planning in the vast region.

        Speaker: Umar Afegbua Kadiri (Centre for Geodesy and Geodynamics, National Space Research and Development Agency, Ministry of Science and Technology)
      • 99
        Seismotectonics of the 2018 Abuja Earthquakes and Probabilistic Seismic Hazard Assessment in Nigeria

        Contrary to earlier beliefs of being aseismic, Nigeria witnessed numerous earthquakes between 2018 and 2022. The 5-7 September 2018 events with moment magnitudes 2.5-3.7 and intensity II-V, occurred in Mpape, Abuja, about three kilometers from Nigeria's presidential villa and critical facilities such as dams, nuclear research reactors, etc. This study aims to adopt an integrated investigation using seismological, geophysical, geological and space-related techniques to ascertain the causes and implications of the seismic activities. Data were acquired from field surveys, local networks and international agencies. A probabilistic seismic hazard assessment was also performed throughout Nigeria and its surroundings. Findings showed the causes of recent seismicity were tectonics, as evidence of a fault was established at Mpape. The b-value, activity rate and regional possible maximum magnitude were 0.69±0.07, 1.684±0.462 and 6.7±0.34. Annual activity rates of earthquake magnitudes 2.0-3.0 are high, while the likelihood of earthquakes of magnitudes 5.0-6.0 occurring annually, 50 years, 100 years, and 1000 years were 0.7%, 75.81%, 99.70%, and 100%, respectively. Return period of magnitude 6.0 earthquake is 143 years. The PGAs for a 10% chance of exceeding in 50 years range between 0.01-0.08g. Results are useful for planning and as baseline parameters for establishing seismic building codes in Nigeria.

        Speaker: Umar Afegbua Kadiri (Centre for Geodesy and Geodynamics, National Space Research and Development Agency, Ministry of Science and Technology)
      • 100
        Study on Source Parameters of Local Earthquakes in Tehri Dam Site and Hinterlands in the Himalayas

        Tehri dam is an earth and rock filled dam situated in the 700 km long earthquake gap in between the 1905 Kangra earthquake in the west and the 1934 Bihar-Nepal earthquake in the east region of Himalaya and built across the Bhagirathi River. The purpose of the dam is to provide irrigation and generate hydroelectricity for nearby areas. It is operated and maintained by Tehri Hydro Power Corporation and monitored by the Department of Earthquake Engineering, IIT Roorkee. The hypocentre parameters of three local events (1.3≤Mw≤3.2) that occurred around the Tehri dam region are estimated using the HYPOCENTER program given in SEISAN software and the code EQK_SRC_PARA was used for earthquake source parameters estimation in which source model fitted in displacement spectra and acceleration spectra. The seismic moments (M0), Brune stress drop and source radii ranges from 2.2×1018 to 6.6×1020, 1 to 63 bars and 65.1 m to 667.4 m, respectively. The maximum stress drop of 63 bars is observed at a source radius of 146.7 m. The radiated seismic energy varies from 1.1×1014 to 3.9×1016. The radiated seismic energy follows the relationship with seismic moment as Es= 3×10-5M01.013. Study advocates that the seismic moment has an increasing trend with increase in source radius.

        Speaker: Daya Shanker (Indian Institute of Technology Roorkee)
      • 101
        Ambient Noise During Nyepi in Denpasar

        Nyepi is a rare activity in the world that only exists in Bali, where all human outdoor activities stop for a day. This study used Nyepi to measure its impact on ambient noise in Denpasar, the capital of Bali province. We used broadband and period seismometer, which operates 24 hours a day, to measure the difference before, during, and after Nyepi. Results of processing signal data using methods Horizontal-to-Vertical Spectral Ratio shows an increase in the dominant frequency during Nyepi, but fluctuating every hour. Overall, the 3-day data dominant frequency is in the range of 1.60-1.70 Hz. The amplification factor at the Nyepi day is at the lowest value compared to the day before and after Nyepi. The seismic vulnerability index when Nyepi is at its lowest value compared to the average before and after Nyepi. The current seismic vulnerability index value of Nyepi is 23 998. This value is 3.906 lower than the average day before and after Nyepi. This suggests that a decrease in human activity has an impact on decreasing the seismic vulnerability index.

        Speaker: Mr I Putu Dedy Pratama (Meteorology, Climatology, and Geophysical Agency of Indonesia (BMKG))
      • 102
        Double-Difference Hypocentral Relocation and Seismic Moment Calculation of Valle de la Trinidad Seismic Sequence, Baja California, Mexico

        Seismic events recorded by the Northwest Mexico Seismic Network are initially located through an automatic system and then manually refined by an analyst. However, this procedure is far from ideal because the considerable dispersion observed in the earthquake cluster does not allow a precise source location. To obtain higher resolution hypocentral locations and thus provide more knowledge and definition of the zone's tectonics, the double-difference algorithm (HypoDD) will be applied to a seismic sequence near the town of Valle de la Trinidad, northern Baja California. This sequence began on August 17, 2020, with an earthquake of local magnitude ML=5.1, and the catalogue to be used for this study will cover until June 2022, resulting in a total of 888 seismic events. This seismicity is still active today and comprises a range of magnitudes from 1≤ML≤5.1. Seismic source parameters of the sequence will be calculated, with particular attention to the seismic moment (Mo), to observe the behaviour of the Mo-ML relationship that several authors have reported as non-linear for southern California and northern Baja California, specifically in the magnitude range 4≤M≤6.8.

        Speaker: Alejandra Martinez (Ensenada Center for Scientific Research and Higher Education (CICESE))
      • 103
        Improve Jordan Seismological Observatory Events Location by Reducing Azimuth Gab Using Regional Seismic Travel Time Workshop Recommendation

        The Jordan Seismological Observatory (JSO) participated in a workshop in Nepal on improved seismic event location using the regional seismic travel time (RSTT) method. The JSO contributed with a list of selected seismic events to be analysed and tested.
        After selecting the most matched event from the list and ensuring it was compatible with RSTT module specification, the result of the analysis of event location by RSTT wasn’t within the expected range. This was because of the high azimuth gab due to lack of stations coverage from all direction.
        The JSO should start to solve this issue by reducing the azimuth gab by adding stations from Lebanon. Additionally, a study undertaken to add new seismic stations where no station coverage is found and by getting data from the International Data Centre or data from other seismological centers.

        Speaker: Shadi Alzoubi (Jordan Seismological Observatory (JSO))
      • 104
        Moment Tensor Solutions of Small to Moderate Earthquakes along Vlora-Elbasani-Dibra Transversal Fault Zone

        The transversal fault zone Vlora-Elbasan-Dibra (VED) with Northeastern strike dislocated the structure of Albanides along all their width. This transverse fault is the most active zone, which has generated earthquakes along its entire length. This study covers the period from 2004 to 2022.,This time period was chosen because it consists of the increase in the installations of digital broadband stations. The seismicity that occurred along VED was well detected by the Albanian Seismological Network and Hellenic Unified Seismic Network, but moderate earthquakes are recorded by almost all seismic stations in the region. For this purpose, data used in this study are broadband waveforms retrieved from online FDSN services which belong to different networks. The data are analysed using the Pyrocko package. This seismic zone has presented interesting characteristics by being activated in different parts of it, continuing from Dumre diapir with complex fault but dominated by dextral strike-slip mechanisms from Elbasani to Dibra region it works as a normal fault with a dextral component of strike-slip, and form Dibra to Mavrovo in North Macedonia as a normal fault in N-E direction.

        Speaker: Mr Olgert Gjuzi (Institute of Geosciences)
    • P1.3 The Oceans and their Properties: e-poster session Zeremoniensaal & Marmorsaal

      Zeremoniensaal & Marmorsaal

      E-poster session with display of each e-poster on an assigned touchscreen

    • P1.4 Multidisciplinary Studies of the Earth’s Subsystems: e-poster session Zeremoniensaal & Marmorsaal

      Zeremoniensaal & Marmorsaal

      E-poster session with display of each e-poster on an assigned touchscreen

    • P5.2 Synergies with Global Challenges: e-poster session Zeremoniensaal & Marmorsaal

      Zeremoniensaal & Marmorsaal

      E-poster session with display of each e-poster on an assigned touchscreen

    • Lightning talks: P1.2-2 Wintergarten

      Wintergarten

      • 105
        Spatial and Temporal Variations in Coda Q Attenuation of Seismic Waves in the Lower St. Lawrence Region, Southeastern Canada

        We investigated seismic attenuation characteristics of the Lower St. Lawrence seismic zone. This zone is located ~400 km downstream from Quebec City and is between the Quebec North Shore and the Lower St. Lawrence. Coda Q was determined using 847 earthquakes (2.0 ≤ M ≤ 5.1) recorded on ten stations of the Canadian National Seismic Network (CNSN) in Quebec from 1985 to 2022. We find that the lowest overall average of Q0 (Q at 1 Hz) values are at the three stations (GSQ, ICQ and SMQ) within 100 km of a moderate earthquake of mN 5.1 in 1999 (e.g., Q0 of 81, 88 and 80, respectively). We determined temporal variations in attenuation following the 1999 earthquake. The overall average of Q0 decreased from 87 (before the mainshock) to 77 (GSQ), from 92 to 85 (ICQ) and from 88 to 82 (SMQ). These results are in agreement with global studies that show a decrease in Q0 following a major earthquake, likely the result of increased fracturing and fluids in the epicentral region. An average for all the data results in a Q relationship of QC = 86f^1.07 for the frequency band of 2 to 16 Hz for the entire region.

        Speaker: Amir Mansour Farahbod (Geological Survey of Canada)
      • 106
        Using a Consistent Travel-Time Framework to Compare Three-Dimensional Seismic Velocity Models for Location Accuracy

        Location algorithms have relied on one-dimensional (1-D) velocity models for fast, seismic event locations. The fast computational speed of these models made them the preferred type of velocity model for operational needs. Three-dimensional (3-D) seismic velocity models are becoming readily available and usually provide more accurate event locations over 1-D models. The computational requirements of 3-D models tend to make their operational use prohibitive. Comparing location accuracy for 3-D seismic velocity models tends to be problematic as each model is determined using different ray-tracing algorithms. Attempting to use a different algorithm than used to develop a model usually results in poor travel-time prediction. We have previously demonstrated and validated the ability to quickly create 3-D travel-time correction surfaces using an open-source framework (PCalc+GeoTess, www.sandia.gov/salsa3d, www.sandia.gov/geotess) that stores spatially-varying data, including 3-D travel-time data. This framework overcomes the ray-tracing algorithm hurdle because the lookup tables can be generated using the preferred ray-tracing algorithm. We have created first-P 3-D travel-time correction surfaces for several publicly available 3-D models (e.g., RSTT, SALSA3D, G3D, DETOX-P2, etc.). We demonstrate using these correction surfaces to compare models fairly and consistently for seismic location accuracy via a set of validation events and International Monitoring System stations.

        Speaker: Mr Michael L. Begnaud (Los Alamos National Laboratory (LANL))
      • 107
        Design Response Spectra for Selected Cities Along the Northwestern Coast of Egypt

        Unknown to the most Egyptians, of all natural hazards earthquakes pose the greatest damage potential. Large scale events are fortunately quite rare, however, if they strike, they can cause far reaching and very costly damage, which lead to potentially hundreds or even thousands of fatalities. So far, earthquakes cannot be prevented or even reliably predicted. But, due to extensive research, much is now known about how often and intensively the earth could shake at given location.
        Probabilistic seismic hazard analysis (PSHA), at the national level, enables societies to make well informed decisions on earthquake safety. On a technical level, a PSHA defines, for building engineers, the kind of ground motions which can be expected for an earthquake and to couple them to the response of local soil and the building characteristics. The design response spectrum considering the different soil conditions for five selected sites along the northwestern coast of Egypt, have been estimated. Seismic hazard maps and design response spectrum are illustrated as selected hazard output for the selected five cities (Alexandria, Alamein, Dabaa, Marsa Matrouh and Negelah).

        Speaker: Hanan Mahmoud Gaber Farghly (National Research Institute of Astronomy and Geophysics (NRIAG))
      • 108
        Improving Location Accuracy for Seismic (GT5) Events in Jordan

        Jordan seismic activities are attributed to the Dead Sea Fault. It is an active transform fault extended from the Red Sea to the Taurus/Zagros Mountains. In cooperation with the Comprehensive Nuclear-Test-Ban Treaty Organization we used available local data, IMS data, and arrival times of seismic events with a magnitude greater than 3.5 to be able to validate the location accuracy. The selected events are local and regional and should satisfy the criteria according to Bondár et al. (2004) to assign and determine the events as ground truth events.

        Speaker: Murad Alhomaimat (Jordan Seismological Observatory (JSO))
      • 109
        Seismicity and Tectonics of the Caucasus Region Revisited

        The Caucasus region lacked a comprehensive catalog, despite its role in Arabia-Eurasia convergence between the Black and Caspian Seas. The Lawrence Livermore National Laboratory and the Institute of Earth Sciences (IES) at Ilia State University generated a new, comprehensive seismic catalog for the period from 1951 to 2019 for the Caucasus region by combining data in the IES bulletin with bulletins of the Republic Seismic Survey Center of Azerbaijan, monitoring centers in Turkey and Armenia, and the ISC.
        We present ~20,000 newly relocated events in this bulletin. We relocated each event using the single-event location algorithm iLoc and regional seismic travel time predictions and identified GT events. We relocated the entire seismicity of the Caucasus region with the multiple-event location algorithm Bayesloc, using the iLoc results as initial locations and the GT events as constraints.
        We show that each relocation step leads to significant improvements, as indicated by tightening of event clusters. The improved view of the seismicity reveals a narrow band of crustal events along the southern flank of the Greater Caucasus we interpret as a megathrust, and confirms both a region of deep seismicity beneath the northeastern Caucasus and a possible area of slab detachment in the central part of the range.

        Speaker: Istvan Bondar (Research Centre for Astronomy and Earth Sciences (ELKH))
      • 110
        Inter-Seismic Strain Accumulation and Estimation of Stress Distribution on the Main Marmara Fault

        The objective of this study is to characterize the recent stress distribution on the Main Marmara Fault (MMF) through quasi-static modeling of inter-seismic strain accumulation by considering past earthquakes and heterogeneous interseismic coupling. Since the MMF is prone to creating large earthquakes, it is crucial to infer the state of stress on the fault. The obtained pre-stress distribution will serve as a basis for simulating dynamic earthquake ruptures via derived stress changes and calculating a realistic map of the peak ground velocity. Due to lack of observed data for future events, International Monitoring System seismic stations may be used to verify future ground motion simulations for destructive earthquakes. To calculate accumulated stress distribution on the locked part of the MMF, interpolated GPS velocities and slip-rates along the unlocked portions of the fault interface are used as boundary conditions. Previous studies of interseismic coupling and seismicity studies including the repeating earthquakes are also considered. A three-dimensional-FEM mesh for the region is built using a mesh size of ~500 m. Consequently, heterogeneous stress distributions are obtained via elaborative usage of recent geodetical investigations. Because the magnitude of stress can’t be measured within the earth crust, such heterogeneous stress change calculations are crucial.

        Speaker: Yasemin Korkusuz Ozturk (Bogazici University)
      • 111
        S Wave Velocity Structure Beneath the San Miguel Volcano, El Salvador, Estimated from Seismic Ambient Noise

        The San Miguel volcano is considered one of the most active volcanoes in El Salvador due to its multiple eruptions; however, its structural properties are not fully understood. Four broadband seismometers were deployed by the Ministry of Environment of El Salvador from February 2014 to April 2014. We analysed ambient noise data using the spatial autocorrelation (SPAC) method and seismic interferometry technique. The SPAC method enabled us to calculate the phase velocity of the surface waves from 0.2 to 1.0 Hz. We derived the SPAC coefficients for each sensor-to-sensor pair (1.5–5.5 km). We directly converted the derived SPAC coefficients to Rayleigh wave phase velocities between 0.2 and 0.4 Hz and inferred phase velocities above 0.4 Hz using the zero-crossing frequencies. We also calculated Rayleigh wave group velocities with seismic interferometry, for each sensor-to-sensor pair. The combined use of the two methods offered ways to gain information about the subsurface seismic velocity structure from the same dataset. Considering the fundamental mode phase and group velocities, the resultant dispersion curve was obtained in a frequency band of 0.2-1.3 Hz. Our results made it possible to perform a joint inversion of phase and group velocities to obtain the S wave velocity structure of the volcano.

        Speaker: Mr Kevyn Pineda (Ministerio de Medio Ambiente y Recursos Naturales)
      • 112
        Seismic Source Modeling for the 2018 Lombok Earthquake Sequence Estimated from the Empirical Green’s Function Method

        In 2018 a series of large damaging earthquakes in Lombok-Indonesia occurred close together, causing many casualties and property damage. Therefore, we conducted source models composed of asperities for the 2018 Lombok Earthquake sequence using strong motion data and estimated by the empirical Green’s function method. We simulated the target event with a smaller event in the surrounding area. Then, the source model parameters were determined by comparing the synthesized to observed broadband ground motions. We obtained the best fit of the size and rupture starting point of the strong motion generation area (SMGA) by doing a grid search calculation. We found that the pulse waveforms extend radially toward the bottom right-hand direction due to the forward directivity effect. Furthermore, there is a relationship among the foreshock, the mainshock, and the largest aftershock that may have triggered each other and have similar source characteristics with rupture directions.

        Speaker: Ms Aldilla Damayanti Purnama Ratri (Meteorology, Climatology, and Geophysical Agency of Indonesia (BMKG))
      • 113
        Small Aperture Seismic Array, Oman

        Seismic array was developed in 1960s mainly to enhance signal noise ratio. Since then many array have been deployed around the world with varying geometry and aperture length based on the purpose of study. Many seismic analyses techniques have been developed, such as beamforming and F-K analysis, in order to achieve the desired results from the data. Hoqain seismic array in Oman is one of the local small aperture array that was deployed in March 2015 with nine 3-C stations and a total aperture of around 2 km and set in complex geological setting of ophiolite and sequence of sedimentary rock in northern Oman. A python scripts is utilized to calculate beam power by scanning the data every one second around the frequency of interest. This study includes searching for slowness and back azimuthal values that can give the optimal beam out of the nine stations. STA/LTA detector is applied for an auto picking through a continuous data stream. The study is able to detect some minor earthquakes around Oman Mountains that our local network is not dense enough to detect. Some of these events can be correlated to known rock mining activity while others could be of tectonic origin.

        Speaker: Mr Yasir Alrawahi (Sultan Qaboos University)
      • 114
        Stress and Deformation Regime in San Salvador, El Salvador, from Inversion of Focal Mechanisms and GNSS Data

        El Salvador is located in northern Central America, along the Pacific Ocean margin. San Salvador is located in a region with a high rate of seismic activity, as it is part of the El Salvador Fault Zone (ESFZ). Currently, there is no detailed information on the stress and deformation regime in San Salvador. In this sense, the present project is oriented to the analysis of the local seismotectonic characteristics, which are intended to be essential inputs for the analysis of the seismic hazard and risk in the capital of the country. It is proposed to elaborate stress and deformation maps based on inversion of focal mechanisms and data from the Global Navigation Satellite System (GNSS), to carry out a statistical analysis of the seismicity recorded from 1984 to 2021 and to correlate macroseismic data with the stress regime. With the inversion of the focal mechanisms, we seek to obtain the main stress axes in the area and calculate the shape factor, which is a measure of the relative magnitude of the predominant stresses. Finally, the classification and inversion of focal mechanisms in the study area will allow a better understanding of the seismic source, whether volcanic, tectonic or anthropogenic.

        Speaker: Ms Rosa Amelia Garcia Castro (Ministerio de Medio Ambiente de El Salvador)
      • 115
        Seismic Microzonation Map of the Chiang Mai Basin, Thailand

        Seismic site effect is a dominant parameter of seismic hazards analysis. We present an experimental study of microtremor data to investigate the dynamic characteristics of soil and structures at the Chiang Mai basin, Northern Thailand. The Chiang Mai basin was constructed on terrace sediments and alluvium sediments. The horizontal vertical spectral ratio (HVSR) analyses of ambient noise data at 101 sites were processed and quality controlled, then interpreted for the amplification factor and fundamental resonance frequency. The results indicate that the low resonance frequency ranges between 0.15–0.4Hz in the middle and indented to the west of the Chiang Mai basin, which is proximity to the location of the basin depocenter. The western edge of the basin has distinctly low frequencies before the highland, indicating that the western edge of the basin has a steep slope. The amplification factor ranges from three to five times in middle of the basin. We also evaluate the shear wave velocity (Vs30) using the HVSR inversion technique, where most of the basin area classified as site D soil (stiff soil) relative to alluvium sediments and the class C soil (very dense soil) conform to the quaternary sediments area are located on the eastern edge of the basin.

        Speaker: Mr Patinya Pornsopin (Earthquake observation division, Thai meteorological department)
      • 116
        Ground Motion Prediction Equation in Thailand

        This research is to study earthquakes strong motion. According to the fact that the factor affecting peak ground acceleration (PGA) is distance, measurement PGA of earthquakes events were collected and have been selected and analysed to find the ground motion prediction equation (GMPEs) in Thailand to estimate seismic hazard or an effected area during a future earthquake in Thailand. The equation can be used to improve the accuracy of seismic hazard maps of Thailand. From a study of 28 local earthquake events, magnitude 3.0 to 6.4 range from 10 km to 600 km from the epicenter with 465 values of data set from seismic stations. In order to make the highest R-squared (R2) of the peak ground acceleration, the researcher has divided GMPEs into three equations according to earthquake magnitude which are less than 4.0, between 4.0 - 4.9 and 5.0 and above. The result of R2 of the peak ground acceleration is 86.63%, 86.17, 57.96, respectively. By comparing to six GMPEs equations in other countries, it is found that Jain's equation conforms to this research for all three equations. Therefore, these equations and Jain's equation can be used as GMPEs, as optional.

        Speaker: Mr Sophon Chaila (Thai Meteorological Department)
      • 117
        Near Surface Non-linear Material Behaviour due to Coupling of Atmospheric Pressure and Solid Earth

        Variations in strain/stress and fluid content can change seismic velocities in the subsurface. Monitoring velocity changes, e.g. using ambient seismic noise, may thus constrain these variations as well as the material elastic properties and their non-linear behaviour. In our study we investigate variations of seismic velocity on a short time scale. We use coda wave interferometry to inspect continuous data from the GERES array (CTBTO network) in southern Germany. This results in relative seismic velocities (dv/v) that show temporal variations on the order of $10^{-4}$. Spectra of the velocity time series contain strong daily and sub-daily behaviour indicating that the daily and sub-daily changes in the seismic velocity are primarily caused by the coupling of atmospheric processes and solid earth. We also note the influence of temperature changes on daily variations, but as a second-order effect. The explanatory model focuses on depth variations of the groundwater table, linking atmospheric pressure (loading and de-loading the Earth's surface) to variations in seismic velocity. Our results highlight an important environmental influence on seismic velocity that needs to be considered before seismic velocity variations can be used for inspecting fluid and stress variations in situ.

        Speaker: Richard Kramer (University of Vienna)
      • 118
        Crust-Uppermost Mantle Structure Beneath the Caribbean Region from Seismic Ambient Noise Tomography

        We present a new 3-D shear velocity model for the crust-uppermost mantle structure beneath the Caribbean region from the surface down to 150 km depth. Our velocity model was derived from joint inversion of group and phase velocity dispersion data obtained from ambient noise and earthquake data. The group and phase dispersion curves estimated from ambient noise were calculated from cross-correlation using up to four years of continuous data. Perturbations in group and phase surfaces wave velocities within a resolution of 1x1 degrees show the relevant geotectonic units in the Caribbean plate. Plate boundaries, ocean basins, rises, rifts and microplates are well defined by shear wave velocity impedances. The 3-D shear wave velocity inversion along profiles shows the thickening of the crust from the ocean to continental margins. We present a new Moho interface map with depths undulating between 11 km and 17 km beneath most parts of the sea and 25 km to 45 km below the continental areas. Low velocity zones were found in the uppermost mantle indicating a highly laterally heterogeneous area.

        Speaker: Bladimir Moreno Toiran (CENAIS. Centro Nacional de Investigaciones Sismologicas)
      • 119
        Rapid Magnitude Estimation Using Local Earthquake Waveform Data and the Application to Earthquakes in Indonesia Including the 2010 Mentawai Tsunami Earthquake

        This study aims to estimate earthquake magnitude quickly using vertical component data from Broadband seismographs for the improvement of tsunami warnings. Empirical relationships were obtained for displacement and integrated displacement with moment magnitude. Data selection of seismic records was done before estimating the relationships of amplitudes by observing the number of amount of data to unselect records with gaps and the maximum amplitude to eliminate spike data. We compared the magnitudes of the formulas for displacement (MD) and integrated displacement (MID). We found that MID yielded better estimates than MD. MID also produced appropriate estimates for earthquakes with strike-slip focal mechanisms. On the other hand, for deep earthquakes, MD yielded a better estimate. In the case of the 2010 Mentawai tsunami earthquake, MID produced an underestimated whereas the estimate was obtained no more than three minutes after the earthquake origin time.

        Speaker: Mr Aziz Widiarso (Meteorology, Climatology, and Geophysical Agency of Indonesia (BMKG))
      • 120
        Seismic Hazard Assessment Along the Central Region Coast of Ghana.

        Ghana is positioned far from any active plate boundaries at the southeastern part of the West African Craton. Elmina, Cape Coast, Saltpond, and Winneba are the four main towns located along the coast of Central region, being one of Ghana's sixteen regions. The seismicity in the regions are stable, with the exception of Greater Accra, Eastern, and part of Volta region that are notable earthquake hotspots. The Central region has been subjected to damaging earthquakes since 1615, when an earthquake was felt in Elmina along the coast of Cape Coast. Tremors have recently been felt by residents of the Cape Coast, specifically at the university Cape Coast campus. Though there were no recordings at the Ghana Geological Survey to support it, verbal communication and observation of some of their structures point to seismic activity in the area. Moreover, a compilation of data from the International Data Centre of the Comprehensive Nuclear Test Ban Treaty Organization reveals the recording of seismic occurrences in the Gulf of Guinea along the coast of Ghana, with the intensity being felt on land. The measured local magnitude (ML) ranges from 2.0 to 4.1, and the body magnitude (Mb) ranges from 2.0 to 4.6.

        Speaker: Ms Ruth Annan (Ghana Atomic Energy Commission (GAEC))
      • 121
        Adjoint Waveform Tomography Models for Improved Moment Tensor Inversions with Three-Dimensional Greens Functions and Sparse Regional Networks

        Seismic moment tensor (MT) inversions have become an important method for characterizing source type (e.g. earthquake, explosion, collapse), seismic moment and depth. However, these methods commonly use average plane-layered one-dimensional (1-D) Green’s functions (GF’s). For areas where path-specific structure is complex, 1-D GF’s cannot fit observed waveforms and source parameters from MT inversions are poorly resolved. These problems are compounded for shorter periods and/or longer paths where structural effects accumulate. We are developing improved three-dimensional (3-D) models on a regional- and continental-scale using Adjoint Waveform Tomography. These models provide improved simulations of regional distance waveforms compared with 1-D models, particularly at far-regional distances, say > 1000 km. MT inversions using 3-D GF’s show greater variance reductions (improved waveform fit) and smaller phase delays between observed and simulated waveforms. We have developed models for the western United States where we have good data coverage for the tomography and ample source types to evaluate MT inversion performance. Results for other regions and will be presented at the conference. We are particularly attuned to MT inversions in tectonically complex parts of the world with sparse regional observations, such as the International Monitoring System.

        Speaker: Mr Arthur Rodgers (Lawrence Livermore National Laboratory (LLNL))
      • 122
        Seismotectonic Setting and Coulomb’s Stress Change for Earthquakes in Aswan, Egypt

        Aswan is a very important city located in the southern part of Egypt, with several cultural heritage sites and critical infrastructure, including the High Dam. The High Dam is located near one of the most seismotectonically active zones, the Kalabsha fault zone. This zone witnessed the strongest instrumental earthquake in Aswan in November 1981, with Mw = 5.8. The current study aims to study the seismotectonic setting of Aswan depending on (1) Updating the fault plane solutions catalogue by constructing the Focal Mechanism Solution (FMS) for the earthquakes that happened in the vicinity of Aswan from 2012 to 2022 (2) stress tensor inversion using the FMS. Also, it was known that Aswan suffered from two historical earthquakes along the Kalabsha fault. In this study, Coulomb’s stress change was estimated for these earthquakes to determine if they occurred along the Kalabsha fault and their relation to the 1981 earthquake.

        Speaker: Mona Abdelazim Abdallah Metwally (National Research Institute of Astronomy and Geophysics (NRIAG))
      • 123
        Seismic Velocity Structure of P-Wave Beneath The Java Region, Indonesia Using Simultaneous Seismic Tomography Method: A Preliminary Result

        Java Island is an area with high earthquake activity, one of these activities is caused by the impact of the Indo-Australian Plate, which hits the Eurasian Plate, causing a subduction zone along Java Island. Besides the subduction route, Java Island also has earthquake sources from active faults. This study aims to image tectonic patterns based on the structure of wave velocity models. The data used are the travel time of P waves from 9238 earthquakes from January 2009 to December 2020 captured by 128 seismic sensor networks. The initial velocity model used in this study is the one-dimensional (1-D) global velocity model AK135. For the simultaneous inversion process, we used SIMULPS12 code. The results of the tomographic inversion show several tectonic patterns. In addition, earthquakes were detected due to volcanic activity and shallow earthquakes associated with the fault line. The horizontal tomogram activity successfully depicts the distribution of volcanic structure under the volcanic array in the study area. The vertical tomogram successfully depicts a slab field that sharpens at a depth of <250 km and a partial melting structure under the volcano.

        Speaker: Mr Mufti Putra Maulana (Indonesian Agency for Meteorological, Climatological and Geophysics (BMKG))
      • 124
        Estimating the Recurrence Periods of Earthquake in Sabah Using the CTBTO International Monitoring System Data

        Sabah is the most seismically active state in Malaysia where it has recorded higher number of moderate seismological activities for the past decades. The seismicity map of Sabah shows the presence of two zones of distinctive seismicity, which are Ranau in Kota Kinabalu and Lahad Datu in the southeast of Sabah. The International Monitoring System (IMS) network set-up by the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) has successfully detected seismic events that occurred in Sabah for the past decades. This paper aims at quantifying the recurrence periods and probabilities of occurrence of earthquake in Sabah using the IMS seismic data. The Extreme Value Distribution Type-I has been applied in this study to evaluate the maximum magnitude data, where the results of analysis have enabled the quantification of recurrence periods and probabilities of occurrence at any given earthquake magnitude. Consequently, the findings from this study could be utilized to further assess the impact of seismic events that are certainly useful to assist relevant entities in planning for disaster management in Sabah.

        Speaker: Mr Muhammed Zulfakar Zolkaffly (Malaysian Nuclear Agency)
      • 125
        Data Assesment and Regional Seismic Travel Time (RSTT) Modelling in Venezuela and the Caribbean Sea

        Geophysical data has been gathered to assess these data sets to achieve reliable earthquake re-localisation. These data would serve as input for the Regional Seismic Travel Time (RSTT ) global model's workflow to achieve accurate RSTT in Venezuela and the Venezuelan part of the Caribbean Sea. Therefore, the data sets are extensive including the compilation of earthquakes, mine blasts and seismic data shots from various seismic projects that have taken place in the last decades, which would serve as a significant improvement in the RSTT model and the International Monitoring System (IMS ) data for re-localization, proposed in the area region. Most of these data sets have served in the past for geological characterization and basin analysis within the oil exploration industry, geohazard assessment, and local velocity model building for a better understanding of seismic risk. However, proper data integration would allow a significant improvement, given the previous efforts made in data integration, to achieve consistent Moho depths that best describe addressing the lateral variations and heterogeneities within the Venezuelan crust, which would benefit improving seismic phases picking for the National Data Center and IMS data.

        Speaker: Ms Keyla Ramirez (Fundacion Venezolana de Investigaciones Sismologicas (FUNVISIS))
      • 126
        One-Dimensional Velocity Model at the Bending of the Southern Carpathians, Inferred from the Analysis of Local Earthquakes

        The purpose of this study is to improve the hazard model and the accuracy of the Romanian earthquake catalogue (ROMPLUS) by determining the one-dimensional (1-D) velocity model in a complex collision setting at the bending of Southern Carpathians. To achieve this aim, we investigate 314 low to moderate-sized local, crustal events (Mw 1.0 - 3.4) that occurred from 2019 to 2021. The waveforms were recorded by the permanent stations of the Romanian Seismic Network (RSN) over a distance of up to 200 km. The P and S wave travel times determined in the selected distance range were inverted using the VELEST algorithm and the IASP91 velocity reference model. The resulting high precision 1-D velocity model and the station corrections were further used to relocate the seismic events recorded in ROMPLUS catalogue within the selected area. Our results provide a significant decrease in RMS location errors and, in agreement with previous findings, show a good correlation with local geological structure. Consequently, the relocated events place key constraints on natural seismicity patterns, representing the first step towards more detailed seismotectonic analyses.

        Speaker: Mx Raluca Dinescu (National Institute for Earth Physics (NIEP))
      • 127
        The Contribution of the Auxiliary Seismic Station MLR in International Data Centre Products and Comparison of the International Data Centre Reviewed Seismic Bulletins with the Bulletins from the National Data Centre of Romania

        Romania's participation in the global system of verification of nuclear experiments by seismological means is carried out within the National Institute for Earth Physics by hosting the National Data Centre of Romania (ROM-NDC) and operating and maintaining the auxiliary seismic station Muntele Rosu (AS081, MLR) as part of International Monitoring System (IMS). The main purposes of this study are first, to compare the reviewed seismic bulletins (REBs) produced by ROM-NDC with the REBs produced by International National Data Centre (IDC) and second, to highlight the use of the MLR station in IDC products for local and regional earthquakes as well as in the ISC bulletins on a global scale. In order to achieve these goals, we are analysing seismic events with a magnitude ML above 3.5, that occurred in 2021 on Romania`s territory and surrounding areas, by applying both statistical methods as well as processing and comparing the data recorded by the Romanian Seismic Network and the IMS network for these events using the Antelope and Geotool softwares. The comparison between IDC and ROM-NDC bulletins shows that an important percentage of such events are commonly missed in IDC REB solutions for the events with a magnitude ML above 3.5 (approx. 50%).

        Speaker: Ms Camelia Andreea Chircea (National Institute for Earth Physics (NIEP))
      • 128
        Toward Macro Seismic Intensities Computation for Bolivian Earthquakes

        Macro seismic intensities are a key factor to support the seismic hypocenter location, moreover, this kind of information contributes to sample the Mercalli Modified Intensities (MMI) felt in each city, which can vary along the earthquake ray path. In our country the MMI has been collected since the OSC-NDC foundation, however, over the last 20 years this task was discontinued due to the lack of a collection protocol. To resolve this issue, since 2018, we re-did an intensity form so people would fill it in. As a result, we produced visually appealing questions and provided check box options. As the Covid-19 pandemic started and forced institutions to migrate to digital and teleworking procedures, we implemented a digital form to fill in through tested information technologies, such as, WhatsAPP and Google Forms. MMI computation output’s goes to a database from where the expert can draw intensities curves and evaluate the effect along a city. The latest results proved that the new digital form works efficiently and enhances the maps along the region that felt the earthquake.

        Speaker: Mayra Nieto Canaviri (Observatorio San Calixto)
      • 129
        Earthquake History in Azerbaijan and Contemporary Days: Challenges Ahead

        This research presents seismic studies review through history up to contemporary days to understand the behavior of earthquake occurrences in Azerbaijan and the interrelation between geodynamics and seismicity. Azerbaijan is situated within the central part of the Mediterranean active belt with seismicity stipulated by intensive geodynamic interrelation of Eurasian and Arabic lithosphere plates. Azerbaijan is characterized by high seismicity with a great number of historical strong earthquakes with М≥6. Developments in seismological instrumentation and power systems have allowed increasing the number of seismic stations in the country since the 2000s for high quality as well as cost effective seismological observations. Great efforts have been directed towards developing probabilistic and deterministic seismic hazard assessment standards in Azerbaijan, plotting analytical models, graphs, maps and understanding their implications for seismic hazard and risk assessments. Rising number of strong and damaging earthquakes in the world, growth of data and knowledge in line with new engineering demands and needs for the operational safety for community initiated the research of more effective approaches incorporating new multidisciplinary concepts and integrated tools. Challenges in exploring recent innovative developments in computational techniques, numerical modeling of classical and new seismology problems is further ahead in Azerbaijan.

        Speaker: Mr Gulam Babayev (Azerbaijan National Academy of Sciences)
      • 130
        Gravimetric Investigation of Geological Structural Anomalies

        We report on advances in capabilities toward detailed three-dimensional (3-D) density evaluation of shallow underground features. We are currently developing software to use a 3-D Geological Framework Model (GFM) to predict gravitational anomalies from underground structures such as faults, cavities or tunnels that might be detected with surface and/or subsurface gravity measurements. This software is being built within a Python operating environment and is leveraging parallelization capabilities of Python to accelerate the computations for large models (billions of elements) parameterized at high resolution. The models ingested by the algorithm are built upon a grid of right rectangular prisms with associated densities. The gravitational contribution of each prism is estimated using the method of Nagy (1966) for each measurement position in a survey. Because the gravitational field is a linear sum of the independent prisms for each station, the problem is well-suited to parallelization. The goal of our development is to build an inverse capability which would allow for iterative model adaptation based upon measured gravity in an area of interest. We present the status of this tool and its application to gravity survey locations at the Nevada National Security Site. LA-UR-22-31036.

        Speaker: Mr Nishath Ranasinghe (Los Alamos National Laboratory (LANL))
      • 131
        Probabilistic Seismic Hazard Studies for Madagascar

        Seismic hazard assessment for Madagascar based on probabilistic analysis method (PSHA) is carried out after determining the three main parameters such as the mean seismic activity rate (λ), the b-value called Gutenberg-Richter value, and the maximum magnitude mmax. An earthquake catalogue was compiled from data combined between two sets of bulletins by the MACOMO and National Data Centre databases. Duplicate events were removed and the catalogue was homogenized to moment magnitude (MW) scale before being declustered. A seismotectonic model for Madagascar developed from latter studies was used for the delineation of seismic source zones. A total of seven areal source zones were introduced in this study. Each zone is characterized in terms of its recurrence parameters and maximum magnitude using the homogenized catalogue. Seismic hazard calculations were performed for a grid spacing of 0.5o x 0.5o throughout the country. The logic tree formalization was implemented to account for uncertainties in the input parameters. The hazard values from 10% and 2% probabilities of exceedance for 50 years are estimated with the spectral accelerations for periods 1.0 s and 3.0 s. Relatively high hazard values were observed within the central regions of Madagascar comparing results from previous studies.

        Speaker: Mr Rakotondraibe Tsiriandrimanana (Institute and Observatory of Geophysics of Antananarivo (IOGA))
      • 132
        Local Seismicity type of Kuwait

        The current manuscript comes to answer a controversial question: Is the local earthquake activity in Kuwait a result of tectonic circumstances or anthropogenic? Kuwait is an oil-producing country from which oil is extracted in many places and earthquakes occur simultaneously with the extraction of oil. Seismic activity inside Kuwait is monitored with high accuracy and continuously after the establishment of the Kuwait National Seismic Network (KNSN) in 1997 through an ambitious plan to study the micro-earthquake activity in Kuwait. The KNSN network recorded more than 1000 micro/minor local earthquakes. Two areas were distinguished in Kuwait in which earthquakes only occur. The recorded earthquakes in those areas are characterized by small magnitudes and shallow focal depths. In the current work, several modern geophysical techniques including waveform inversion, Double-Couple and Compensated Linear Vector Dipole signatures, stress drop values, and stress patterns have been used to distinguish between types of seismicity of different origins. The results obtained clearly show that the earthquakes that occur in Kuwait involve tectonic and anthropogenic components. This means that the local earthquakes in Kuwait occur in places that have active network faults and are triggered by the oil extraction in these places alone.

        Speaker: Mr Abdelaziz Khairy (Kuwait institute for Scientific Research (KISR))
      • 133
        Nonlinear Elasticity: Application to Resolve the Stress-Field Orientation from Ambient Seismic Noise

        Crustal rocks containing cracks and other internal flaws are characterized by nonlinear elasticity, a phenomenon that can be observed in laboratory experiments under applied stress. Stress sensitivity of elastic moduli is associated with opening/closing of cracks under applied stress. In this study we emulated rock laboratory protocols by measuring elastic wave speed using empirical Green’s functions (probe) at different points of earth tidal strain cycle (pump) in natural pump-probe experiment to infer the orientation of SHmax in the crust, independently from borehole measurement and earthquake mechanisms. We validated the approach using large data set in the Northern Alpine Foreland region where SHmax orientation is well-known. The approach is then applied to the Central Eastern Alps to understand contemporary stress pattern. We confirm that the method can be applied in large scale seismic arrays. For the validation area it resolves NNW-SSW to N-S directed SHmax which agree with conventional methods and recent crustal stress model. Furthermore, our results show rotation of SHmax orientation from NW-SE in the southwest of Central Eastern Alps to N-S in the east of the Central Eastern Alps. The approach can also be applied to nuclear test sites, provided that there are continuous seismic stations in the region.

        Speaker: Yongki Andita Aiman (University of Vienna)
      • 134
        Detection, Localization and Characterization of the Seismicity: Deep Learning Methods for Accuracy Improvements of Regional Seismic Bulletins

        The recent strong densification of seismic networks and the increase of data availability from different type of sensors/networks (low-cost, Raspberry-shake, temporary deployments with hundreds of nodes, etc.) questions our ability to automatically and accurately detect, locate and characterize seismic events combining these composite and large data sets. These steps are however key issues to monitor natural and anthropogenic seismic activity, an important goal of the CTBTO community. Here we present a protocol/workflow that takes into account the latest advances in deep learning methods for seismology, aiming to automatically build seismic bulletins and discriminate/label events, for national needs as for scientific research. We validate this protocol/workflow and proved its robustness to different sets of data, from the local scale of a dense seismic network (200 nodes), to a regional scale of a temporary broadband network completed by Raspberry-shakes (Pyrenees and Bolivian Altiplano). We show the gain reached both in terms of calculation time and hypocentral location accuracy. The increase in accounted phase picks due to joint use of permanent/ temporary/low-cost sensors, and automatic deep learning based approaches, provides more exhaustive and accurate seismic bulletins, leading to a better characterization of the regional seismicity and allow the construction of trustable natural and anthropogenic seismic events database.

        Speaker: Mr Benoit Derode (University of Toulouse & Commissariat à l’énergie atomique et aux énergies alternatives (CEA))
      • 135
        Local Site Characteristics Around the PS14-ROSC Seismic Station

        The primary seismic station PS14-ROSC is located near the town of Rosal in the central part of the eastern cordillera, close to the Colombian National Seismological Network headquarters. The signal to noise ratio of seismic data shows low quality data. Using the power spectral densities (PSD), we analysed changes in the seismic background noise levels in the station. We integrated microtremor measurements with geological observations to characterize the local site effects of the station and surrounding area in order to find an optimal place to relocate the bunker and improve the quality of the data. We conducted miniature microtremor array measurements to estimate the S wave velocity structure beneath the studied area. The spectral relationship of the horizontal components with the vertical H/V allows us to estimate the fundamental period of the ground. We calculated the phase velocity dispersion curves of Rayleigh waves using the methodologies SPAC, CCA, NC-CCA and we inferred the shear wave velocity profiles Vs by inversion technique.

        Speaker: Patricia Pedraza Garcia (Colombian Geological Survey)
      • 136
        The Mw 6.7 21 July 2021 Panama Fracture Zone Earthquake

        Seismic data collected by the Costa Rican OVSICORI-UNA seismic network is used to study the spatiotemporal seismicity and tectonic, related with the Mw 6.7, 21 July 21:15:07, 2021 earthquake, located in the Panama Fracture Zone, 114 km south of the Burica Peninsula. In this zone the relative motion of the Cocos and Nazca plates, accommodates the stress mainly by right-lateral strike-slip motion along the Panama Fracture System as supported by relocated fore and aftershocks distribution and calculated moment tensor nodal plane of the main event (strike=186º, dip=88º, rake=-152º). The rupture evolution started from south of epicenter, moving north toward mainland, rupturing over 45 km in length and 30 km width, reaching a maximum slip of 0.6 m.

        Speaker: Ronnie Quintero (Observatorio Vulcanológico y Sismológico de Costa Rica, Universidad Nacional (OVSICORI-UNA))
      • 137
        Reimaging the Fennoscandian Microseismicity

        The conventional picture of the seismicity in Finland, and the rest of Fennoscandia, has been that earthquakes are mostly individual or doublet events without fore or aftershocks. This notion of apparent singularity is based on automatic detection and classification tools and manual analysis workflow designed for regional events visible on multiple stations over a relatively sparse seismic network. On the other hand, in Wyborg rapakivi batholith, located in south-east Finland, earthquakes have been known to exhibit a more swarm type behaviour, where a single larger – ML 1.0 to 3.0 – event can be surrounded by tens if not hundreds of smaller events above ML 0.0. In this study, we apply a cross-correlation based event detection suite, developed for a dense array based seismic network monitoring enhanced geothermal system in the Helsinki capital region, to various Fennoscandian earthquakes. Using a template created from a selected earthquake, the suite is able to identify smaller seismic events with a location and source mechanism similar to the template event. In areas with a dense station coverage, we can detect events down to ~ML -1.0. This provides us with an improved image on the nature of microseismicity related to the Fennoscandian earthquakes.

        Speaker: Mr Tommi Antton Tapani Vuorinen (University of Helsinki, Institute of Seismology)
      • 138
        Comparison of Mb (IDC) to Mb (ISC) for the East Africa Region Using the Empirical Regression Equations

        Data collected from IRIS Reviewed Bulletin for East Africa is used to generate empirical regression equations using orthogonal least square regression (OLSR). The regression best-fit line yields a regression equation y=0.517x+ 2.1787 with R2 0.6208 for 972 events with a cut-off magnitude of 2.5. While the R2 error is relatively high the result compare published regression equations. The slight variations may be due to the IDC body wave calculation method. The equation bridges the data gap where no other magnitude type is provided and allows for the extension of the seismic catalogue by 22 events not reported by any other network. Further, it helps increase our understanding of the seismicity of the region and contributes to more representative hazard mapping.

        Speaker: Ms Gladys Kianji (University of Nairobi)
      • 139
        Seismic Tomograms of the Uppermost Subcontinetal Lithosphere in Southern Africa Based on P Wave Arrival Times from Local, Regional, and Mining-Induced Earthquakes Recorded by SASE and International Monitoring System Stations

        Seismic tomograms of the uppermost subcontinental lithosphere (USCL) beneath southern Africa are key to improving knowledge of the correlation between the surface geology and velocity anomalies in the region. The regional distribution of seismic wavespeed anomalies (SWAs) provides a means to delineate known structural features and to find new regions of SWAs within the model space. Delineated SWAs enable a better understanding of the relationship between SWAs and the USCL density and thermal variations. The present study investigates the anatomy of the USCL beneath southern Africa by tomographic inversion of absolute P wave arrival times from local, regional, and mining-induced earthquakes recorded by 82 broadband stations of the 1997–1999 Southern Africa Seismic Experiment (SASE) and three seismic stations of the International Monitoring System (IMS) located in the study area. The P wave geotomograms were determined through the application of a hybrid iterative tomographic inversion method in which travel times and ray paths are calculated rapidly and accurately using a 3-D ray tracer, and the linearized iterative inversion utilizes the conjugate gradient-type LSQR algorithm. The reliability of the SWAs was assessed through checkerboard resolution test. The geotomograms determined in the present study indicate that the P wave speed structure of the USCL is heterogeneous across southern Africa.

        Speaker: Tarzan Kwadiba (Botswana International University of Science and Technology)
    • P1.2 The Solid Earth and its Structure - 1: part 1 Zeremoniensaal & Marmorsaal

      Zeremoniensaal & Marmorsaal

      E-poster session with display of each e-poster on an assigned touchscreen

    • P3.1 Seismic, Hydroacoustic and Infrasound Technologies and Applications Zeremoniensaal & Marmorsaal

      Zeremoniensaal & Marmorsaal

      E-poster session with display of each e-poster on an assigned touchscreen

    • P3.4 Integrating data of Different Monitoring Technologies Zeremoniensaal & Marmorsaal

      Zeremoniensaal & Marmorsaal

      E-poster session with display of each e-poster on an assigned touchscreen

    • P4.5 On-site Inspection Team functionality Zeremoniensaal & Marmorsaal

      Zeremoniensaal & Marmorsaal

      E-poster session with display of each e-poster on an assigned touchscreen

    • PTS session 1: Oral session, part 1 Prinz Eugen Saal

      Prinz Eugen Saal

      • 11:30
        PTS session introduction
      • 140
        26 Years of Development of the International Data Centre (IDC)

        After opening for signature of the CTBT (24 September 1996), the PTS began working on the establishment of a global verification regime to monitor its compliance (17 March 1997). The verification regime includes both non-technical and technical elements (defined in Article IV of the treaty); while non-technical refer to diplomatic actions and confidence building measures within States Parties, the latter involves the construction of a complex system built on science, strategy and technology that is divided into three large groups (teams) gradually establishing and operating (in provisional mode) the IMS, the IDC and the OSI. This presentation is a historical collection of highlights on the development of the IDC to date.

        Keywords: PTS Provisional Technical Secretariat, IMS International Monitoring System, IDC International Data Centre, OSI On-Site Inspection.

        Speaker: Ms Zeinabou Mindaoudou Souley (CTBTO Preparatory Commission)
      • 141
        Infrasound Technology at the IDC – projects and achievements

        In 2001, the first data from an IMS infrasound station arrived at the IDC. The IDC infrasound processing system was in a premature state and a multi-year development effort was initiated, which led to the completion in 2010 to the first operational infrasound automatic processing and interactive analysis systems. In thirteen years the IDC produced over 45,000 infrasound events reviewed by expert analysts.
        In an effort to continue advancing methods, improving its automatic system and providing software packages to authorized users, the IDC focused on redesigning the station processing and interactive review systems. This lead to the development of DTK-(G)PMCC promoted to IDC operational environment on 01 July 2022. The software package is available in NDC-in-a-Box (NiaB) to authorized users.
        In complement, an infrasound model was developed for the automatic waveform network processing software, NET-VISA, with an emphasis on the optimization of the network detection threshold by identifying ways to refine signal characterization methodology and association criteria.
        Those major endeavours allow for the enhancement of the IDC processing system, to reduce workload of analysts and to continuously increase the quality of IDC bulletins. Progresses will be illustrated with notable infrasound events since promotion of the new Operational software.

        Speaker: Pierrick Mialle (CTBTO Preparatory Commission)
      • 142
        Scheduled Calibration of IMS infrasound stations

        Calibration activities for infrasound stations of the International Monitoring System (IMS) are a requirement of the Operational Manual for Infrasound Monitoring and the International Exchange of Infrasound Data. Until 2011, significant technical and scientific challenges prevented full compliance with these requirements. This included the absence of available techniques to characterize responses in operational conditions. To address these challenges, the PTS coordinates the development of a detailed infrasound technology roadmap, and works together with the scientific, metrology, and sensor manufacturing communities. This collaboration led to the deployment of calibration capabilities at infrasound stations of the IMS, starting with a first station in 2015. This presentation illustrates the Scheduled Calibration process as currently defined at the PTS for infrasound stations, past progress, and current challenges. As of 2022, calibration capabilities have been rolled out successfully at 34% of the certified infrasound IMS stations (18 stations). A dedicated software (CalxPy) was also designed to support the calibration process for all stations having calibration capability in a centralized manner in Vienna. These calibration results are reported since 2019 to Member States.

        Speaker: Yacine Sid Ahmed (CTBTO Preparatory Commission)
      • 12:20
        PTS session concluding remarks
    • O2.3 Seismoacoustic Sources in Theory and Practice: part 1 Forum

      Forum

      Conveners: Mr Atalay Ayele (Addis Ababa University (AAU)), Paulina Bittner (CTBTO Preparatory Commission)
      • 11:35
        Session introduction
      • 143
        The Rock Valley Direct Comparison Experiment: An Overview

        In 1993, a shallow earthquake sequence occurred in Rock Valley, Nevada National Security Site. The largest event, M3.7, was followed by eleven M>2 events ranging in depth from 1-3 km. All events were well constrained due to the deployment of stations early in the sequence. Comparison of these shallow events to nearby historic nuclear tests identified gaps in our ability to discriminate these event types. To answer the question about the physics of shallow earthquakes, the Rock Valley Direct Comparison Experiment was conceived. We will conduct two chemical explosions at similar hypocenters to the earthquake sequence to understand the discrimination features between these types of events. We have systematically relocated the 1993 events, varying velocity models and codes, but using a common pick data set to choose the experiment borehole. Three additional boreholes are planned and will be instrumented to obtain microseismicity data, sample fault properties, and record the chemical explosions. We are installing a dense seismic network, including re-occupying stations that recorded the 1993 earthquakes. We have developed a 3-D geologic framework model for visualization, and for modeling and simulation efforts. We expect this unprecedented data set will address seismic waveform differences between earthquake and explosion sources.

        Speakers: Ms Catherine Snelson (Los Alamos National Laboratory (LANL)), Mr Robert Abbott (Sandia National Laboratories (SNL))
      • 144
        Simulations and Analyses of Source Physics Experiments: Impact on Explosion Monitoring and Discrimination

        The Source Physics Experiments (SPE) are a series of controlled chemical explosions at the Nevada National Security Site to gather observations, validate physics-based numerical models and understand the genesis of shear waves to improve nuclear discrimination and monitoring capabilities. Executed between 2011 and 2016, Phase I of SPE encompassed six collocated chemical explosions executed in hard granite with different yields at different depths. Phase II included four chemical explosions executed in 2018 and 2019 in soft dry alluvium. Phase III, however, includes two planned chemical explosions in a dominant dolomite geology and collocated with a 1993 shallow earthquake. LLNL has developed a comprehensive numerical framework to simulate from source-to-receivers, the waves generated from the non-linear explosion source-region to linear-elastic seismoacoustic distances. We present the analysis of SPE Phases I & II collected data, summarize how modeling predictions compared to observed data and draw lessons learned. We share insight on the main mechanisms of generating shear motions in granite, alluvium and dolomite. Moreover, we developed schemes of uncertainty propagation of the geological characterization and geophysical parameters. We present impacts of those uncertainties on designing of Phase III tests, predicting the near-field responses of planned tests, and enhancing source discrimination.

        Speaker: Mr Souheil Ezzedine (Lawrence Livermore National Laboratory (LLNL))
      • 145
        Seismic Source Characterization and Screening with Moment Tensors: Case Study of the mb 4.7 Mining Event in Kiruna, Sweden, on 18 May 2020

        On 18 May 2020, a seismic event with mb 4.7 and MS 3.9 (International Data Centre) occurred in Kiruna, northern Sweden, at an active iron mine (Luossavaara-Kiirunavaara AB, LKAB). This event was widely observed at broadband seismic stations throughout Nordic countries and as far away as Iceland, Greenland, the UK and continental Europe. Both the operating mining company and various seismological agencies have reported the event as induced or anthropogenic. However, screening procedures at the International Data Centre reported an MS/mb score of -2.03, and as a result the event could not be screened out as non-nuclear in origin. Using waveform data from all possible International Monitoring System stations and openly available seismic stations, we estimate moment tensors with uncertainties for this and other events using the methodology of Alvizuri et al (2018) which has proven successful in characterizing and screening various other events, including the six nuclear tests in the Democratic People's Republic of Korea and a collapse event eight minutes after the 2017 nuclear test at the same location. The results for the nuclear tests reveal mechanisms with positive isotropic parameters, while collapse events as observed at Kiruna and the Democratic People's Republic of Korea reveal negative isotropic parameters, which suggest that future screening criteria would benefit from using moment tensors and source-types.

        Speaker: Mr Celso Alvizuri (Norwegian Seismic Array (NORSAR))
      • 12:25
        Session transition
    • 12:30
      Lunch break
    • O2.3 Seismoacoustic Sources in Theory and Practice: part 2 Forum

      Forum

      Conveners: Mr Atalay Ayele (Addis Ababa University (AAU)), Paulina Bittner (CTBTO Preparatory Commission)
      • 146
        The Korean Infrasound Bulletin: Detection, Association and Event Location

        Long term infrasound event bulletins are useful for identifying repeating sources from a common location, quantifying source characteristics and studying the time-varying nature of the atmosphere. We produce a regional infrasound bulletin in the Korean peninsula region for the time period from 1999 to 2021. We use data from six infrasound arrays in South Korea, cooperatively operated by Southern Methodist University and Korea Institute of Geoscience and Mineral Resources, and from two International Monitoring System infrasound stations in Russia and Japan. The detection procedure uses an adaptive F-detector that inputs arrival time and back azimuth into the Bayesian Infrasonic Source Location procedure. The bulletin consists of 34 218 events spanning over 23 years and produces locations indicative of repeated events from many different source types, including shallow-depth earthquakes, explosions from limestone mines and quarry operations. Most events occur during working hours and days, suggesting a human cause. We quantified the false association using the perturbed detection time simulation and reviewed the events with many associated arrays. The ray tracing using the Ground-to-Space atmospheric model generally predicts the infrasound arrivals when strong stratospheric wind exists, while local weather data can contribute to explaining the propagation path effects to arrays in some cases.

        Speaker: Junghyun Park (Southern Methodist University)
      • 147
        The use of a Local Infrasound Mobile Array and the International Monitoring System IS42 Station in Monitoring Seismovolcanic Crisis on São Jorge Island, Azores in 2022

        The São Jorge seismovolcanic crisis in 2022 provided an opportunity to deploy a portable infrasound array (SJ1) on the island, in a collaborative work between the University of the Azores (UAc) and the University of Florence (UniFI). This four-element array became operational on 2 April 2022 firstly with a diamond geometry, and after 3 May 2022 with a centred triangular design. Therefore, SJ1 in association with the International Monitoring System infrasound station IS42, located on Graciosa Island at ~41 km distance, formed a temporary monitoring network, aiming to assist the monitoring activities related with the volcanic unrest in São Jorge Island. Both have different equipment, mainly regarding on sensor's type: SJ1 is composed of four differential pressure transducers and the signal is digitized at 100 sps, while IS42 is formed by eight absolute microbarometers rearranged into a three-element triangular small aperture within a five-element pentagonal aperture and signal digitized at 20 sps. We present here two examples of detections registered: (1) seismoacoustic signals associated to a low magnitude earthquake at São Jorge, and (2) a meteor offshore north of São Miguel Island, allowing to validate the overall detection capability and the importance of this type of solution to monitor local seismovolcanic activity.

        Speaker: Maria do Céu Jesus (Instituto de Investigação em Vulcanologia e Avaliação de Riscos (IVAR))
    • O3.6 Analysis of Radionuclide Monitoring Data Prinz Eugen Saal

      Prinz Eugen Saal

      Conveners: Abdelhakim Gheddou (CTBTO Preparatory Commission), Anders Ringbom (Swedish Defence Research Agency (FOI))
      • 13:30
        Session introduction
      • 148
        Machine Learning Enhanced Detection of Radionuclide Anomalies

        Atmospheric concentrations of radionuclides measured at International Monitoring System (IMS) stations can vary by an order of magnitude or more between neighboring stations and from one collection to the next due to changes in weather, emission rates of background sources and other local factors. Large spatiotemporal changes make it difficult to categorize elevated collections as anomalies of interest or something benign. Simple univariate quantile scores are easy to calculate from time series of individual radionuclides at single IMS stations, but they do not account for correlated anomalies across different collections or different isotopes within a collection. In this presentation, we demonstrate the advantages of using machine learning algorithms routinely used to detect fraudulent activity in the financial industry for identifying radionuclide anomalies. Unsupervised machine learning anomaly detection algorithms, such as isolation forests and local outlier factors, can provide quantitative scores that consider a multitude of information. These algorithms run quickly, are easy to train, and, with relatively little effort, could be automated to process streaming IMS data. We also demonstrate supervised machine learning approaches, such as Bayesian ridge regression, to improve radionuclide anomaly detection through the incorporation of simulated signals from one or more atmospheric transport models.

        Speaker: Dr Donald Lucas (Lawrence Livermore National Laboratory (LLNL))
      • 149
        Reconstruction of Synthetic Radionuclide Source Terms Using Bayesian Inference

        The Forensic Radionuclide Event Analysis and Reconstruction (FREAR) tool performs source reconstruction using a Bayesian inference framework. Using a statistical model of the radionuclide detection system and atmospheric transport models, FREAR infers and reconstructs the best emission source characteristics to fit the supplied observations. This powerful approach provides assessments of source location, release magnitude, release period, compares observed and posterior predicted measurements and ultimately reduces the area of consideration of potential sources.
        To test the suitability of FREAR for verification applications, blind synthetic trials were constructed at two different environmental scales, using WRF-HYSPLIT. These two scenarios were then reconstructed by FREAR at three different organizations using different dispersion and meteorology model input (NCEP-HYSPLIT, ECMWF-FLEXPART, CMC-MLDP). The results of the two trials will be discussed, showing that FREAR represents a dramatic improvement in radionuclide event assessment, providing a valuable tool to National Data Centres. The future development of the FREAR tool will be shared.

        Speaker: Ian Hoffman (Radiation Protection Bureau, Health Canada)
      • 150
        The Development of an Association Algorithm for Radionuclide Measurements

        The International Monitoring System operates a network of radionuclide technology monitoring stations. Historically, each measurement has been analysed separately to verify treaty compliance. Combining sample measurements, including detects and non-detects, invokes greater monitoring capability referred to as network power. A key steppingstone to obtaining network power is to objectively select a group of related sample measurements that are associated with a release event. Such collections of measurements can be assembled by an analyst, or perhaps they can be selected by algorithm. The authors explore, using a year of atmospheric transport calculations and realistic sensor sensitivities, the potential for a computed radionuclide association tool.

        Speaker: Mr Harry Miley (Pacific Northwest National Laboratory (PNNL))
      • 151
        A Baseline for Source Reconstruction Using Forensic Radionuclide Event Analysis and Reconstruction

        Inverse modelling allows to determine source parameters of an atmospheric release of radioactivity by combining atmospheric transport modelling and airborne radionuclide measurements in a statistically coherent manner. A series of inverse modelling experiments will be conducted using real-world Xe-133 observations from the International Monitoring System and the Forensic Radionuclide Event Analysis and Reconstruction tool to determine the (known) source parameters of the former medical isotope production facility CNL. The purpose of these experiments is to establish a baseline for source reconstruction from which new settings, new data, and/or new methods can be easily tested. Testing can include, but is not limited to: (i) different source parameterizations, (ii) different optimization formalisms, (iii) applying background-corrected Xe-133 observations and (iv) different atmospheric transport model input. In this study, the inverse modelling baseline will be presented together with a series of tests. A set of metrics for evaluating inverse modelling will be explored which will allow us to compare the performance of experiments with the baseline.

        Speaker: Pieter De Meutter (Belgian Nuclear Research Center (SCKCEN))
      • 152
        Performance Evaluation of Radioxenon Isotopic Ratio Flags and Possible Optimizations

        In the context of CTBT verification, radioxenon ratios can be used to discriminate between nuclear weapons domain signatures and nuclear facilities as plausible sources of the observed atmospheric radioactivity. This discrimination is accomplished by setting a screening flag threshold beyond which a radioxenon sample can be considered as being possibly of relevance from a nuclear explosion monitoring perspective. The goal of this study was to evaluate the currently implemented method for setting screening flag thresholds and to explore potential enhancements. First, a data set was analysed comprising approximately 35 000 samples of International Monitoring System (IMS) radioxenon data. Using activity concentrations and reported uncertainties, the ratios Xe-135/Xe-133, Xe-133m/Xe-133, Xe-133m/Xe-131m and Xe-133/Xe-131m were quantified for each IMS sample using two different methods for handling uncertainty and three different confidence intervals. The sets of obtained ratios were then used to determine new thresholds based on three different false positive rates. To test the performance of each screening flag, signatures of a hypothetical explosion were combined with observations from IMS samples and the resulting radioxenon ratios were compared to the newly established threshold. The detection rate for each of the 18 screening flag threshold calculation methods was quantified to enable the selection of the most suitable method.

        Speaker: Emily Gordon (The University of Texas at Austin)
      • 14:50
        Session concluding remarks
    • O4.4 International Monitoring System Sustainment Forum

      Forum

      Conveners: Ms Paola García (Comisión Chilena de Energía Nuclear), Ms Xyoli Pérez Campos (CTBTO Preparatory Commission)
      • 14:00
        Session introduction
      • 153
        Failure Classification and Monitoring of Radionuclide Systems Using State of Health Data

        Sensor data from radionuclide systems within the International Monitoring System (IMS) provides critical information about the operating status of a given station. Many of the algorithms currently in place monitor large immediate sensor deviations and provide alerts. Small sensor changes, especially over extended periods of time, are more challenging to detect. Another challenge is quickly identifying the root cause of failures automatically such that strategic maintenance can be performed. Pacific Northwest National Laboratory (PNNL), in collaboration with General Dynamics, has been developing an architecture for monitoring IMS radionuclide systems that is capable of testing new algorithms. One of the new techniques being investigated is classifying failures based on the sensor data available. The goal is to use knowledge from experts together with new data science techniques (such as artificial intelligence and machine learning) to determine the failure mode using groups of sensors as a signature. This presentation will discuss the current state of health monitoring architecture and the latest developments in the failure mode sensor signature algorithm development.

        Speaker: Reynold Suarez (Pacific Northwest National Laboratory (PNNL))
      • 154
        Modernization and Sustainment

        Modernization of technology and work processes during the last decade at NORSAR. How technology, state of health (SOH) monitoring and efficient work processes can contribute to quality, data availability and increased performance. In the last few years NORSAR has established a modernized SOH system based on Nagios, PostgreSQL and Grafana to monitor and log uptime and SOH of our installations and processes. An increased focus on risk mitigation and remote control capabilities has, together with the improved SOH tools, meant more efficient operations and higher uptime. Through risk analysis NORSAR has identified some of the challenges of the future. This presentation will give an overview of NORSARs experiences in lifecycle management and SOH monitoring system for efficient operations and sustainment of large International Monitoring System array stations. It will also look at the financial aspects and challenges of long term sustainment of large scale infrastructure and potential high impact risk factors within operation and sustainment of such stations.

        Speaker: Mr Jon Magnus Christensen (Norwegian Seismic Array (NORSAR))
      • 155
        The Auxiliary Seismic Network of the International Monitoring System Challenges and Opportunities: An International Monitoring System Perspective

        The auxiliary seismic network of the International Monitoring System (IMS) is comprised of 120 seismic stations. It is designed to support the primary seismic network to increase detection accuracy, for earthquake monitoring and nuclear test detection. Some auxiliary stations have been designated as temporary substitute primary stations. Auxiliary seismic stations are deployed at remote areas around the globe, many are hard to access often in harsh climatic conditions and occasionally facing security issues; some are approaching or exceeded 15 years of age since certification. Thus equipment replacement must be considered and failure, obsolescence and replacements must be addressed with greater frequency. The Provisional Technical Secretariat (PTS) provides remote technical support for troubleshooting, training of station operators, implementation of authentication and data transport, in accordance with the terms of the CTBT Treaty (Article IV). However, support is limited if the resulting action requires financial expenditure from the PTS. The direct consequence of this limitation is amplified if the host country is not capable of meeting the maintenance costs, thus resulting in station outages sometimes prolonged. We discuss the performance of the auxiliary station network and recommend solutions for the short and long term to improve maintenance practices and achieve better results.

        Speaker: Mr Jose Pereira (CTBTO Preparatory Commission)
      • 14:50
        Session concluding remarks
    • Panel discussion on 3D wave propagation modelling Festsaal

      Festsaal

      • 156
        Developments in three-dimensional (3D) wave propagation modelling and wave conversion at the ocean, land, and atmosphere interfaces, for infrasound and hydro-acoustic signals Festsaal

        Festsaal

        The CTBT-IMS global sensor network comprises three waveform technologies: Seismic, hydroacoustic, and infrasound, designed to monitor the world continuously for any nuclear explosions on the ground, in the ocean, and the atmosphere. Waveform signals at CTBT-IMS stations can present complex arrival characteristics caused by 3D features along their long-range propagation paths. This panel will debate the challenges in 3D modelling of long-range sound propagation in the ocean and the atmosphere. The panelists will discuss recent advances in 3D modelling of seismic-to-acoustic and acoustic-to-seismic energy conversion at the ocean, land, and atmosphere interfaces.

        Speaker: Charlotte Rowe (Los Alamos National Laboratory (LANL))
    • O2.5 Historical Data from Nuclear Test Monitoring: part 1 Forum

      Forum

      Conveners: Ms Anna Berezina (Institute of Seismology, National Academy of Sciences of the Kyrgyz Republic), Mr Martin B. Kalinowski (CTBTO Preparatory Commission)
      • 14:55
        Session introduction
      • 157
        Spatio-temporal Variations of Short-period S Wave Attenuation Field in the Region of the Semipalatinsk Test Site (Using Recordings of Nuclear and Chemical Explosions)

        We have been considering spatio-temporal variations of S wave attenuation field structure in the region of the Semipalatinsk test site (STS). We studied variations of amplitude ratio for Lg and Pg waves (parameter Lg/Pg) using seismograms of underground nuclear explosions (UNEs) and also calibration and quarry explosions, obtained by stations TLG and MKAR. We revealed essential temporal variations of parameter Lg/Pg for the UNEs at three main sites of the STS. At the end of 1980s mean Lg/Pg values are considerably lower for the Balapan site in comparison with two other sites. We have studied characteristics of S coda envelopes using recordings of the chemical explosions, obtained by close stations on the STS territory. The data obtained show that minimal quality values for temporal stations in the STS region (~40-55 for frequency 1.25 Hz) are considerably lower than in the seismically active North Tien Shan region (~60-80). It is supposed that the spatio-temporal variations of the attenuation field structure in the STS region are connected with deep-seated fluids migration in the earth’s crust and uppermost mantle, stipulated by long term intensive UNEs influence on the geological medium.

        Speaker: Ms Inna Sokolova (Geophysical Survey Russian Academy of Sciences)
      • 158
        Historical Nuclear Test and Collapse Data from the Livermore National Network Between 1979-1992

        Historical geophysical data recorded during the peak of nuclear testing is rare and limited. Efforts have been made to preserve and digitize data but have minimal quality control from decades of lost history and retiring personnel. Furthermore, recent research into the subsequent collapses of cavities is stifled by the lack of continuous records to investigate historical collapses.

        The Livermore National Network (LNN) was a 4-station seismic network in California, Nevada and Utah that recorded nuclear and tectonic events starting in the 1960s. Here, we present previously unreleased data from LNN containing over 100 recorded nuclear tests as well as over 50 collapses associated with a nuclear test. We will discuss the challenges and mitigation efforts we undertook to preserve and correct any errors in the digitization, waveform rotation and metadata.

        Speaker: Ms Amanda Price (Lawrence Livermore National Laboratory (LLNL))
    • O3.3 On-site Inspection Techniques: part 1 Prinz Eugen Saal

      Prinz Eugen Saal

      Conveners: Aled Rowlands (CTBTO Preparatory Commission), Mr Gregor Malich (INSPECC)
      • 14:55
        Session introduction
      • 159
        Method for Estimating the Tripartite Array Back-Azimuth Error Caused by the Far-Field Approximation

        In recent decades, the tripartite micro arrays (i.e. three-element array) became a major tool for the passive seismic phase of the on-site inspection, mainly due to their superior back azimuth estimation. However, the back azimuth is estimated under the assumption of far field approximation while tripartite arrays are used to monitor micro-seismicity and aftershocks in the vacancy of the array. Thus, in the region where the far field assumption might not hold. In this work, we determine the effect of breaking the far field assumption by analyzing the plane wave errors, i.e. the errors of the back azimuth and slowness computations caused by the plane wave assumption. Computational formulas for estimating the absolute errors, due to the plane wave assumption, were developed. A case study utilizing the subarrays of the IMS station MMAI, demonstrate that the plane wave errors are not the theoretical issues only but taking them into account can improve the results of field measurements.

        Speaker: Dr Yochai Ben-Horin (NDC Israel)
      • 160
        A Comparison of Portioning Samples Under the Comprehensive Nuclear-Test-Ban Treaty Organization, the Organisation for the Prohibition of Chemical Weapons and the International Atomic Energy Agency

        The Comprehensive Nuclear-Test-Ban Treaty language on an Inspected State Party’s right to portions of samples taken during an on-site inspection (OSI) is very similar to sampling language in the Chemical Weapons Convention (CWC), reflecting an overlap amongst negotiators involved. There are small differences in the treaties’ wordings, however, and in the case of the CTBT these differences have made it difficult for State Signatories to reach consensus on how to implement portioning of samples during an OSI. Meanwhile the CWC has been in force for 25 years, during which time the OPCW has developed procedures for inspectors to portion samples, though not all aspects of inspections or portioning have been fully exercised. Likewise, IAEA inspectors take samples during inspections and, while the concept of portioning may not be as explicit, procedures allow for the ISP to retain their own relevant samples. We examine how the ISP right to sample portions is practiced at the OPCW and IAEA and draw insights from their experiences to compare with the approaches considered at Preparatory Commission meetings.

        Speaker: Mr Brian Milbrath (Pacific Northwest National Laboratory (PNNL))
    • Highlight talk Festsaal

      Festsaal

      • 161
        Examples of U.S. Transparency and Verification Supporting Nuclear Nonproliferation

        The United States supports the Comprehensive Nuclear-Test-Ban Treaty (CTBT) and is committed to work to achieve its entry into force, recognizing the significant challenges that lie ahead in reaching this goal. Consistent with the goals of the CTBT, the United States continues to observe a moratorium on nuclear explosive testing and calls on all states possessing nuclear weapons to declare or maintain such a moratorium. The United States has no plans to conduct a nuclear explosive test.

        This invited talk will provide examples of transparency related to activities at U.S. nuclear security enterprise sites such as the Nevada National Security Site (NNSS) and the national laboratories. The United States shares significant information about its plans and operations and is open with the international community about Stockpile Stewardship activities such as subcritical experiments and the recent fusion breakthrough as well as nonproliferation-related field experiments at NNSS.

        Examples of U.S. support for the CTBT will also be discussed, including the recent acceptance of the next generation Xenon International noble gas analysis system for use in the International Monitoring System (IMS), IMS component testing, U.S. funding for the maintenance, operation, and improvement of its IMS stations, and extensive support for the International Data Centre Re engineering project.

        Speaker: Ms Corey Hinderstein (National Nuclear Security Administration)
    • 15:30
      Coffee break
    • O2.5 Historical Data from Nuclear Test Monitoring: part 2 Forum

      Forum

      Conveners: Ms Anna Berezina (Institute of Seismology, National Academy of Sciences of the Kyrgyz Republic), Mr Martin B. Kalinowski (CTBTO Preparatory Commission)
      • 162
        General Discussion of Analog Seismic Data, and (at last) an Origin Time for the First Nuclear Explosion (TRINITY)

        Radio timing services failed for the first nuclear test (TRINITY, 16 July 1945), but were available to determine the origin time of an earlier 108 ton TNT explosion, conducted nearby on 7 May, 1945. We have scanned and digitized the vertical-component analog seismograms recorded at Tucson Observatory (TUO, at a distance of 437 km) for both events. These regional signals include Pn and Pg, and presumably Sn and Lg. We applied cross-correlation methods of analysis to the regional seismic window, finding that the faint signals of 7 May provide a satisfactory cross-correlation peak when compared with the 16 July signals. Our best estimate of TRINITY's origin time is 11:29:24.5 (GMT), good to a few tenths of a s. This result is significantly different from official reports. We give this specific result in the context of making three general points: (1) analog records are necessary to document the wide range of features of nuclear explosion seismograms; (2) modern cross-correlation methods of analysing seismograms can be effective and simple to use, in application to analog recordings of complicated weak regional seismic signals; and (3) there is merit in developing a complete list of basic parameters of historic nuclear test explosions.

        Speaker: Mr Paul Granston Richards (Lamont-Doherty Earth Observatory, Columbia University)
      • 16:15
        Session concluding remarks
    • O3.3 On-site Inspection Techniques: part 2 Prinz Eugen Saal

      Prinz Eugen Saal

      Conveners: Aled Rowlands (CTBTO Preparatory Commission), Mr Gregor Malich (INSPECC)
      • 163
        Explosion Anomaly Detection from Thermal Infrared Photogrammetry

        Photogrammetry, a technique to create high resolution orthoimagery and digital elevation models from a collection of photos, has rapidly evolved since the 1990s. Traditional photogrammetric techniques assist in a wide variety of fields, including facilitating high resolution change detection for underground explosion monitoring and verification. Typically, this method involves the use of standard electro-optical imagery using visible band data. By repurposing and enhancing existing photogrammetric techniques and applying those techniques to thermal infrared data collected before and after a conventional explosive experiment, we developed a novel method for processing thermal images for signature detection. This thermal photogrammetry method provides a new way to detect post-explosion anomalies and artifacts, quantify extent of site changes, and characterize fragmentation materials and distribution from explosions. Additionally, this technique can be applied to data collected from ground based or airborne platforms, providing a novel tool to characterize larger sites We present these new methods for thermal data processing, discuss the results of a field campaign, highlight the successes of the technique, and define next steps for realizing data collection efficiencies and advancing data processing.

        Speaker: Mr Brandon Crawford
      • 164
        Unmanned Aerial Vehicle (UAV) Technology for Nuclear Disarmament: A Responsible Innovation Perspective

        In the current age of technological innovation detecting illicit underground testing of nuclear weapons is a challenging task. However, remote sensing technology like unmanned aerial vehicles (UAV) is trying to provide solutions to some unresolved problems in our society and environment. UAV is a new and emerging technology that has a direct impact on the economy and society. It has a wide range of applications in many sectors like agriculture, insurance, energy and utilities, infrastructure, mining, media and entertainment. The technology is capable of capturing microscopic information with minute details and accuracy. UAVs can collect remote sensing data unhindered in adverse weather conditions even under clouds. UAVs can thus be used as surveillance technology in places where there is a threat of nuclear armament. The deployment of the technology also requires retaining values like accuracy, accountability, and efficiency. In innovations literature, the responsible innovation approach enables us to look into the question of accountability. Responsible innovation thus becomes significant as a theoretical framework. The study would address as research questions: How far technology like UAV can fulfill the objectives of CTBT? How can the framework of responsible innovation help in studying the issue of illicit nuclear testing?

        Speaker: Mr Anjan Chamuah (NUNV Project Officer: Village Resources Assam, UNDP)
      • 16:30
        Session concluding remarks
    • Panel discussion on Metrology Festsaal

      Festsaal

      • 165
        International measurement equivalence – a fundamental backbone for IMS

        Since 1875, the Metre Convention has established the principles for all nations to act in common accord in matters relating to units of measurement. In 1960 the system became known as the International System of Units (abbreviated SI from the French "Système International d'Unités"). Today, the SI is the widely accepted basis for the international mutual recognition of measurement results and provides confidence in measurement data traceable to this system.
        This seemingly simple system of mutual recognition of measurement data across international borders and trading economies is based on the "CIPM-MRA", an international recognition arrangement under the CIPM, which came into force in 1999. Its implementation involves national metrology institutes and regional metrology organisations in a permanent infrastructure that ensures the international equivalence of measurements.

        In the establishment and operation of such a complex network as the IMS, the CTBTO can realise significant benefits by linking to the SI and the associated metrology processes and rules that underpin this system. Recognising the potential benefits of linking to the SI, the CTBTO contacted the CIPM in 2017 and initiated a formal liaison in 2021.

        This talk will present a history of the unification of the metric system under the Metre Convention, the development of a global network to enable CIPM-MRA, and some common technical highlights related to CIPM and CTBTO.

        Speaker: Mr Takashi Usuda (National Institute of Advanced Industrial Science and Technology (AIST))
      • 166
        Operating the IMS in the framework of the International System of Units (SI)

        Any system that intends to provide reliable and trustworthy information demands quality processes that are commensurate with the complexity of the system and criticality of the data. The IMS is highly demanding in both respects. Therefore, the quality system infrastructure being developed and implemented for the IMS seismo-acoustic operations aims at realising these goals through unprejudiced operational procedures and objective data analysis.
        This panel will consider the implications for the evolving quality system, building on the latest international developments in low-frequency sound and vibration metrology, such as the European Infra-AUV project.
        Potential impacts and benefits include; improvements in the credibility of data through traceability to the International System of Units (SI) and knowledge of the associated uncertainty, and enhanced operational transparency and impartiality enabled by conformity assessment. The panel will consider the practicalities in implementing these innovations into IMS stations operations, alongside evolving best-practices across seismo-acoustic technologies, within the wider quality system developments.
        Collectively, the panel members provide leading expertise in metrology and the provision of specialist measurement services, and in the vital operational considerations for the effective adoption of new developments. The panel will also address questions and issues that the broad spectrum of stakeholders may wish to raise.

        Speaker: Mr Richard Barham (Acoustic Sensor Networks Limited)
    • O3.5 Analysis of Seismic, Hydroacoustic and Infrasound Monitoring Data Forum

      Forum

      Conveners: Mr Christos Saragiotis (CTBTO Preparatory Commission), Mr Paul Granston Richards (Lamont-Doherty Earth Observatory, Columbia University)
      • 16:20
        Session introduction
      • 167
        Testing and Design of Discriminants for Local Seismic Events Recorded During the Redmond Salt Mine Monitoring Experiment in Utah

        The Redmond Salt Mine Monitoring Experiment in Utah was designed to record seismoacoustic data at distances less than 50 km for algorithm testing and development. During the experiment from October 2017 to July 2019, six broadband seismic stations were operating at a time, with three of them having fixed locations for the duration, while the three other stations were moved to different locations every one-and-half to two-and-half months. Redmond Salt Mine operations consist of nighttime underground blasting several times per week. Redmond Mine is located within a belt of active seismicity, allowing for easy comparison of natural and anthropogenic sources. Using the recorded dataset, we built 1373 events with local magnitude (Ml) of -2.4 and lower to 3.3. For 75 blasts from the Redmond Salt Mine (RMEs) and 206 tectonic earthquakes (EQs), both Ml and coda duration magnitude (Mc) are well constrained. To separate the population of RMEs from the group of EQs, we experimented with several discriminants, including the difference Ml-Mc, Rg/Sg spectral amplitude ratios, low frequency to high frequency Sg, and Pg/Sg amplitude ratios, and different combinations of two or more of these discriminants. The effectiveness of these discriminants at classifying the events is discussed.

        Speaker: Mr Rigobert Tibi (Sandia National Laboratories (SNL))
      • 168
        Quality Assessment of the Review Event Bulletin Through Comparison with the ISC bulletin for the Month of October 2020

        An attempt is made to assess the quality of the Review Event Bulletin (REB) by comparing it to the Bulletin of the International Seismological Centre (ISC Bulletin). To compare, the ISC Bulletin events as downloaded from the ISC Web page for the month of October 2020 was used. The corresponding IDC REB events as listed in the ISC Bulletin were considered. During this period, a total of 3431 and 2691 events were considered for ISC and IDC, respectively. The comparison was performed using the information given for common events in the header lines of the ISC Bulletin from which matched events could be extracted. The result showed that a total of 2315 events could be matched between the two bulletins. The percentage of matched events with location difference (D) < 1o is about 95.3% while the percentage of events with D ≥ 5o is about 0.3%. There were two events with magnitude (mb) ≥ 4.0 and D ≥ 5o. The percentage of matched events with intersecting error ellipses is 57.0%. In general, the results obtained in this study show that there is a slight difference when compared to the results obtained for similar study made earlier.

        Speaker: Fekadu Kebede Alamneh (Addis Ababa University)
      • 169
        Enhancing Signal Detection at International Monitoring System Seismometer Arrays

        Seismometer arrays form the core of the International Monitoring System (IMS) waveform network, and enhancing signal detector performance should lead to improvements in the performance of all subsequent parts of the International Data Centre (IDC) waveform processing pipeline. Recently a test data set was released by the IDC composed of signal detections made by an implementation of the generalized F detector (Selby 2008, 2011, 2013) at multiple IMS seismometer arrays. In this presentation we will cover the following related topics: i) the performance of the generalized F detector in this test data set in comparison with the existing signal detection algorithm used at the IDC; ii) if and how to apply f-k analysis to detections made by the generalized F detector, and iii) outline approaches to the physical characterization of signals observed at IMS arrays to enhance the performance of the generalized F or other detectors.

        Speaker: Neil Selby (Atomic Weapons Establishment (AWE) Blacknest)
      • 170
        Current Status of NET-VISA Toward the Operational use for Nuclear Explosion Monitoring

        The International Data Centre (IDC) of the Comprehensive Nuclear-Test-Ban Treaty Organization continues to develop the advanced automatic and interactive software NET-VISA, which uses state of the art machine learning and artificial intelligence techniques to do next generation automatic seismic event detector, based on Bayesian inference. The automatic seismic event bulletins it creates, which are called Standard Event Lists (SEL), are the first IDC products which would indicate the presence of a suspicious explosive incident; thus, the performance of the automatic event detector is key for building the capacity of verification regime. In the present study, we will discuss the results of testing the latest version of NET-VISA, which includes several newly developed features, such as the full pipeline configuration that represents the operational environment, and the incorporation of event screening criteria. The performance of NET-VISA as based on the review of a human analyst is discussed.

        Speaker: Vera Miljanovic Tamarit (CTBTO Preparatory Commission)
      • 171
        New Periodic Fisher Scoring Method for DOA Estimation for Seismic Signals

        Seismic waves are sound waves emitted by, for example, an earthquake or an underground explosion. Accurate estimation of the back-azimuth, i.e. the direction of arrival (DOA), of a seismic signal to the detecting station, is required for the accurate localization of seismic events. This is especially important in the case of seismic arrays, which comprise a substantial portion of International Monitoring System primary stations. In this research, we develop a new low-complexity DOA estimation method, the iterative periodic Fisher’s scoring. In our simulations, we use synthetic data that was generated assuming the configuration of the MMAI seismic array and noise characteristics. We compare the performance of the proposed method, the maximum likelihood estimator, and the conventional Fisher scoring as well as the cyclic Cramér-Rao lower bound. Simulation results show that the proposed periodic Fisher’s scoring estimator has a lower mean cyclic error and lower computational complexity than the classical method, and it is more stable around the edges of the range [-pi,pi]. Moreover, under a misspecified model, where the noise is assumed to be white (i.e. uncorrelated between the sensors), while it is colored (i.e. correlated), our methods significantly outperforms the existing methods.

        Speaker: Malaak Khatib (Ben-Gurion University of the Negev)
      • 172
        Detection and Modeling of Timing Errors at Seismic Arrays

        Accurate timing is both an essential requirement and a perennial problem for seismology. With the adoption of satellite based global positioning systems for the timestamping of data in the 1990s, this problem appeared to have been solved. I have applied multichannel cross-correlation (VanDecar & Crosson, 1990) to recordings of teleseisms across seismic arrays, to estimate the relative timing error between array elements. At the Yellowknife seismological array, timing errors are observed at some array elements, up to a maximum of 0.4 s, while others exhibit no apparent timing errors. The relative timing errors between 2014 and 2020 are quantized, with a base value of approximately 0.12 s. The time period can be divided into two eras; within each era the timing error only increases. The cause of the timing errors is unknown, but the quantization is inconsistent with what is expected for a free running clock, and no timing errors have been observed since a digitizer firmware upgrade on 8 April 2020. A model is developed for the absolute timing errors, one which can be applied to historical data. It is recommended that timing error checks be done at other International Monitoring System arrays.

        Speaker: Nick Ackerley (Canadian Hazards Information Service (CHIS), Natural Resources Canada (NRCan))
      • 17:55
        Session concluding remarks
    • O2.4 Atmospheric and Subsurface Radionuclide Background and Dispersion Prinz Eugen Saal

      Prinz Eugen Saal

      Conveners: Jolanta Kusmierczyk-Michulec (CTBTO Preparatory Commission), Mr Jonathan Bare (CTBTO Preparatory Commission), Mr Man-Sung Yim (Korea Advanced Institute of Science and Technology (KAIST))
      • 16:35
        Session introduction
      • 173
        Revisiting What a Variety of Tracers can tell about the Occurrence of Underground Nuclear Explosions

        Underground nuclear explosions induce a strong flow of air through the surrounding fractured porous media, which carries radionuclides or chemical species. While radioxenon and 37Ar represent tracers scrutinized by the International Monitoring System and On-Site Inspection, respectively, a larger variety of tracers is emitted at the ground surface: radioxenon and heat generated by the explosion, radon and carbon dioxide naturally occurring underground and in the soil cover, respectively. The objective is to determine the conditions under which these additional tracers would help to better discriminate the origin of air masses and reduce uncertainty regarding the origin of radioxenon in cases of high background signals.
        This objective can be achieved by a recent code, which solves flow, tracer transport and thermal effects through a fractured porous medium on the Darcy scale (Pazdniakou et al., Pure Appl. Geophys., https://doi.org/10.1007/s00024-022-03038-4, 2022).
        The influence of fractures and of their volumetric density is shown to be crucial on the evolution and the distribution of the tracers at the surface. The natural atmospheric fluctuations play an important role on the instantaneous tracer releases. A soil cover smooths out the ground distribution. Finally, all the previous exhalations appear to be sufficiently large to be measurable.

        Speaker: Pierre Adler (Sorbonne Université)
      • 174
        Potential Impact of Molten Salt Reactors on Radionuclide Stations of the International Monitoring System

        Molten Salt Reactors (MSRs) are a Generation IV nuclear reactor design that is currently under development and testing in various countries around the world. The molten fuel provides an opportunity for continuous processing of gaseous fission products which may impact the International Monitoring System (IMS). Simulations were performed for four MSR designs to predict the production of IMS-relevant radionuclides during batch and continuous reprocessing schemes. Radioxenon and radioiodine signatures were drawn from these simulations and compared to current reactor designs (BRW, PWR, RBMK). For the case of continuous reprocessing of the fuel salt, the radioxenon and radioiodine signatures were found to be indistinguishable from a nuclear explosion.

        Speaker: Johnathan Slack (Pacific Northwest National Laboratory (PNNL))
      • 175
        Evaluation of the Phase II Test of Xenon International on Mount Schauinsland - What can be Gained from Higher Sensitivities and Shorter Sampling Periods?

        We will review data from Phase II testing of Xenon International at RN33. Xenon International is a new generation radioxenon monitoring system developed by PNNL with a short sampling time of 6 hours. Phase II testing of Xenon International was conducted from July 2021 to April 2022 at International Monitoring System (IMS) radionuclide monitoring station RN33 on Mount Schauinsland, Germany. Activity concentrations of spiked and selected environmental samples were verified by reanalysis in either one of the IMS laboratories or the BfS noble gas laboratory in Freiburg. The activity concentrations measured by Xenon International are consistent with data from the current operational IMS system SPALAX at RN33, with sensitivities of Xenon International up to one order of magnitude higher for Xe-131m, Xe-133m and Xe-135. We will investigate multiple isotope detections and unusual single detections and explore the benefits of a 6 hour time resolution taking into account new ATM backwards calculation with hourly resolution.

        Speaker: Ms Sofia Brander (Federal Office for Radiation Protection (BFS))
      • 176
        Solution of the National Data Center Preparedness Exercise 2019 by Using Inverse Atmospheric Transport Modelling

        The National Data Center Preparedness Exercise 2019 (NPE- 2019) provides an opportunity to evaluate the ability of the National Data Center (NDC) to use available International Monitoring System (IMS) data, techniques, and tools to verify compliance with the Comprehensive Nuclear-Test-Ban Treaty. In NPE-2019, there are unusual detections of radioactive particulates (Cs-134, Cs-137, La-140, and Ba-140) and noble gases (Xe-133, Xe-133m, and Xe-135) at some IMS stations. This NPE can be solved by data fusion between solutions of seismic and infrasound detections and the forward atmospheric transport modelling. However, the current work will illustrate the ability to use adjoint atmospheric transport model outputs, source-receptor sensitivity (SRS) fields from radionuclide IMS stations and the corresponding concentrations values of those multidetections to confine the source region and to estimate the source term.

        Speaker: Mr Sayed Mekhaimer (National Research Institute of Astronomy and Geophysics (NRIAG))
      • 177
        Argon-37 Field System Measurements

        This presentation will highlight background measurements of Ar-37 samples that were conducted at in Knoxville, Tennessee, USA to better understand the sources of atmospheric concentrations of Ar-37 using the Argon-37 Field System. The PNNL designed and built Argon-37 Field System has now processed and measured several hundred Ar-37 samples from both the soil gas and from the atmosphere. The system was designed to process whole air samples from soil gas, the atmosphere and from the output of radioxenon systems to detect Ar-37 in an above ground portable system. During this campaign, samples were collected at location, near Xenon International, and sent back to PNNL for processing and measurements as opposed to sending the system to a location and operating it remotely. Correlation with radioxenon measurements from the same air mass were conducted and will be discussed.

        Speaker: Mr James Hayes (Pacific Northwest National Laboratory (PNNL))
      • 17:55
        Session concluding remarks
    • Standardization Festsaal

      Festsaal

      • 178
        Standardization, conformity assessment and certification

        The need for common understanding and adoption of good practices and measurable ways to ensure safety and security in the development and deployment of different technologies are some of the "Raisons d'être" of standardization and certification. This presentation aims to create awareness about standardization, some areas of relevance for the CTBT, while encouraging dialogue with regards to standardization and certification gaps and needs.

        Speaker: Mr Ravi Subramaniam (Institute of Electrical and Electronic Engineers (IEEE))
    • Keynotes by professional societies Festsaal

      Festsaal

      • 179
        Introduction of the synergies between professional societies and the CTBTO

        The purpose of the panel on “Introduction of the synergies between professional societies and the CTBTO” is to introduce the audience to the professional societies that are represented on the podium and to inform about their CTBT-related activities.
        There is no discussion expected but Q&A will be permitted.

        Speaker: Ms Sanam Shantyaei (CTBTO Preparatory Commission)
    • Side Event - Working at the CTBTO - Recruitment Session 1 Forum

      Forum

      • 180
        Working at the CTBTO - Recruitment Session Forum

        Forum

        CTBTO is hiring professionals in STEM fields – Learn about CTBTO’s Recruitment Process
        Come and find out more about how to join the CTBTO! Visit us at the HR booth and speak with the CTBTO Human Resources team and learn more about CTBTO careers. You can also join us in our HR presentation where we will walk you through our recruitment process. CTBTO is hiring top talent across a wide variety of scientific and technical fields in seismic, radionuclide, hydroacoustic and infrasound technologies. There will also be a presentation focusing on students and young professionals interested in pursuing a career in these fields. We look forward to meeting you soon!

        Speakers: Ms Hema Kularatne (CTBTO Preparatory Commission), Ms Marta Fernandez de Mazarambroz (CTBTO Preparatory Commission)
    • e-poster virtual session 1 Online

      Online

      7-8 video rooms in parallel for topics: P1.2 (1 or 2 video rooms), P1.3, P1.4, P3.1, P3.4, P4.5, P5.2

    • Lightning talks: P2.1, P2.3, P4.4 Wintergarten

      Wintergarten

      • 181
        Advantages and Issues of Applying Machine Learning Based Denoising on Inversions of the Democratic People's Republic of Korea Nuclear Tests

        We apply a current state-of-the-art machine learning based denoising algorithm on the seismological and hydroacoustic waveform records of the selected Democratic People's Republic of Korea nuclear tests. We use the DeepDenoiser algorithm to reduce the noise present in the waveform records of the larger Democratic People's Republic of Korea nuclear tests. The denoising of waveform records using machine learning has obvious advantages on the picking of phases and signal detection but the question is if the currently available techniques can be used beyond that. We investigate the impact the denoising has on the source mechanism inferences by comparing the seismic moment tensor inversion results of original and denoised data. Because of the good signal to noise ratio and as the source type is well known we can in this case establish if the denoised waveforms can be used for further source analysis. We find that care needs to be taken using the modified waveform data but also find promising results hinting at possible further use of the technique in the future for standard analyses. We further investigate if the application of the chosen denoising algorithm allows for the better resolution of the seismic moment tensor of the smaller Democratic People's Republic of Korea nuclear tests.

        Speaker: Andreas Steinberg (Federal Institute for Geosciences and Natural Resources (BGR))
      • 182
        Mis-associated Surface Waves Within the Automated Processing Flow of the Reviewed Event Bulletin

        When monitoring for potential underground nuclear tests, distinguishing shallow earthquakes from explosive sources can often be achieved using the ratio of the body-wave magnitude to the surface-wave magnitude (mb:Ms), as explosive sources often produce less energetic surface wave excitations than earthquakes with the same mb. Current methods for surface-wave detection at the International Data Centre (IDC) rely on a dispersion test. A global group-speed model is used to predict a time window based on origins in the IDC Reviewed Event Bulletin (REB). The waveforms in the predicted time window are filtered into eight frequency bands - if the time of the maximum energy of at least six of these bands sits within a specified error of the expected dispersion curves, a surface wave is detected. The current version of this algorithm was implemented into provisional operations at the IDC in 2010 (Maxpmf). We have designed interactive software to review the IDC automatic surface-wave detection algorithm. We investigate mis-associated surface wave arrivals in the REB, caused by a processing limit of surface wave detection to 100 degrees distance. Examples of surface waves originating from greater than 100 degrees distance and being associated with a closer event are presented.

        Speaker: Mr John Condon (Atomic Weapons Establishment (AWE) Blacknest)
      • 183
        Radioxenon to Radioiodine Ratios in Emissions from Nuclear Power Plants

        For the purpose of monitoring for compliance with the Comprehensive Nuclear-Test-Ban Treaty (CTBT), the International Monitoring System (IMS) includes 80 sites with particulate radionuclide samplers, 40 of which also have a noble gas sensor system. The coincidence of radioiodine and radioxenon observations at the co-located systems may offer an opportunity for event screening. This study gains knowledge of typical radioxenon to radioiodine ratios of releases from nuclear power plants (NPPs) and compares these ratios with the signatures that may indicate a nuclear explosion. The study presented here builds on the previous publication about the radioxenon emission inventory from NPPs for the calendar year 2014. The radioiodine emissions of the same reactors will be retrieved, and the distribution of the ratios established for the atomic masses of 131, 133 and 135 as well as for the most frequently observed isotopes of these two elements, namely Xe-133/131I. The purpose of this presentation is to investigate whether these radioxenon to radioiodine ratios can be used for screening methods and to enhance understanding of the impact of known sources on the IMS background observations.

        Speaker: Mr Martin B. Kalinowski (CTBTO Preparatory Commission)
      • 184
        Exploring the use of Radioxenon to Radioiodine Isotopic Ratios as Additional Screening Method Regarding Possible CTBT-relevant Events

        Xenon and iodine isotopes are, among other CTBT-relevant radionuclides, major indicators for nuclear explosions. They are therefore globally monitored by the International Monitoring System to verify compliance with the CTBT, using different technologies. Xenon isotopes are intermediate decay products of radioiodine. If originating from the same source, the radioxenon to radioiodine ratio of isotopes from the same mass chain may be suitable for additional screening of events. This study investigates the radioxenon to radioiodine isotopic activity concentration ratios, as they occur in samples of co-located noble gas and particulate systems that significantly overlap in sampling time. These IMS observations are compared to ratios of the same isotopes for different sources that may be observed. These are simulations of nuclear explosions and nuclear facilities (NPPs and MIPFs), as well as empirical data from published reports for both historic nuclear tests and for releases from nuclear facilities. Based on this comparison, conclusions can be drawn on the usefulness of radioxenon to radioiodine ratios for event screening in CTBT monitoring.

        Speaker: Mr Martin B. Kalinowski (CTBTO Preparatory Commission)
      • 185
        Analysis of Anomalous Seismic Events in India

        The US National Data Centre (NDC) observed five relatively large seismic events in the Chhattisgarh Province of India from September 2018 through October 2022. These events are of interest as they exhibit some explosive characteristics, and their respective yields are approximately equivalent to a 1 kiloton underground nuclear explosion. The events occurred near a known coal mine that uses retreat style mining, which has been known to cause catastrophic collapses at other mining areas. The US NDC conducted Interferometric Synthetic Aperture Radar (InSAR) analysis in concert with waveform correlation and cluster analysis to show that these events can likely be attributed to randomly occurring collapses at the mine. Further, the radius of the InSAR observed surface deformation was compared to the theoretical cavity/chimney radius of an equivalent size underground nuclear test. This comparison excludes the possibility of the events being nuclear related.

        Speaker: Mr Thomas VanDeMark (Air Force Technical Application Center (AFTAC))
      • 186
        Using Low Frequency Electromagnetic Signals to Explore Historic Nuclear Test Observations

        Impulsive, low frequency, electromagnetic signals were observed during historic United States underground nuclear tests. The source of these signals is uncertain though a prime candidate is the so-called “magnetic bubble”. This mechanism creates a magnetic signature when the hot plasma shell from the explosion expands in the Earth’s magnetic field. At low frequencies, this signal can diffuse to the surface where it can be detected. We have conducted experiments with an underground synthetic source at the Nevada National Security Site to emulate possible magnetic bubble signals and to investigate propagation through the intervening overburden. The synthetic source has a peak magnetic dipole moment of 100 kA-m2. The signals from the source can be detected at ranges of several hundred of meters through the saturated tuff overburden using commercially available induction magnetometers and capacitive electric field sensors. The principal noise sources in our experiments have been anthropogenic noise (utility 60 Hz and harmonics) and impulsive atmospheric noise.

        Speaker: Mr William Junor (Los Alamos National Laboratory (LANL))
      • 187
        A Case Study on Using High Resolution Atmospheric Transport Modelling on Historical Democratic People’s Republic of Korea Announced Tests

        Detection of radionuclides released from a nuclear explosion is an essential task performed by the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) as mandated under the Comprehensive Nuclear-Test-Ban Treaty. Identifying possible source regions for relevant radionuclide observations and identifying potential stations for measuring releases from known source locations is done by atmospheric transport modelling (ATM). The CTBTO currently investigates the potential benefits of using high resolution ATM (HRATM). Past announced underground nuclear tests at the Punggye-ri Nuclear Test Site from the Democratic People’s Republic of Korea are used as case studies to scale CTBTO’s capability to identify sites of the International Monitoring System (IMS) that might detect a hypothetical release. These events are also used to identify the capability to locate Punggye-ri as the possible source location. The current study evaluates the performance of CTBTO’s HRATM approach compared to previous results. Variations in spatial resolution of meteorological input data (0.5° to 0.01°), meteorological models European Centre for Medium-Range Weather Forecasts
        (ECMWF) and Weather Research and Forecasting Model (WRF), ATM models (Flexpart and Flexpart-WRF) and physical parameterization demonstrate the sensitivity to configurations. Evaluating the potential increase in accuracy by using metrics from previous ATM challenges shows what enhancements can be acquired with HRATM and what configuration works best.

        Speaker: Ms Anne Tipka (CTBTO Preparatory Commission)
      • 188
        Transportable Absolute Yields of Underground Nuclear Explosions

        The framework developed and presented here provides a new and transportable method to determine the yields of seismically recorded underground nuclear explosions. The key advantage of this method over other methods which estimate absolute explosive yields is that this method does not require any a priori calibration and can be immediately applied to any region of interest. This method uses the source information obtained from the spectral ratios of envelopes of measured seismic coda waves to simultaneously invert for the source parameters describing a set of seismic events including both explosions and earthquakes. The only requirement of this method is that the source region must contain several (>3) seismic sources which have been well recorded (SNR > 2) by a set of shared stations. For regions with only a few events and/or extremely band-limited observations, for which the depths of burial are unknown, an earthquake with a known magnitude may be required to obtain accurate and robust yield estimates. We apply this method to the six declared Democratic People’s Republic of Korea nuclear tests and report new independent absolute yield and depth of burial estimates which are commensurate with previously determined source parameters.

        Speaker: Mr Brent Delbridge (Los Alamos National Laboratory (LANL))
      • 189
        Development of Automatic Procedures for Selecting Samples Associated with a Release Event Based on the Evolution Consistency of Isotopic Ratios

        The International Data Center (IDC) at the Comprehensive Nuclear-Test-Ban Treaty Organization routinely analyses data from radionuclide measurement stations of the International Monitoring System (IMS) in support of its mandate. The Standard Screened Radionuclide Bulletin (SSREB) is a product of the IDC that is generated for each radionuclide sample having measured concentrations of CTBT-relevant radionuclides above abnormal thresholds. In addition, States Parties can request an expert technical analysis (ETA) in which IDC experts perform an in-depth analysis of IMS data with the possibility of including additional data to produce the State Requested Methods Report (SRMR). To facilitate radionuclide ETA, automatic procedures have been developed that assist experts in sample selection and event association based on the consistency of isotopic ratio evolution utilizing measurements from multiple radionuclide samples. The implementation of automatic procedures enables experts to gain an improved understanding of release events and assists experts to more quickly produce the SRMR. Furthermore, automatic processing can identify sample sets which are used to validate new methodologies. In this presentation we will describe the algorithms developed for automatic procedures and show preliminary results. Building from these developments, we plan to improve the automatic processing algorithms to contribute to other IDC products such as the SSREB.

        Speaker: Mr Joshua Kunkle (CTBTO Preparatory Commission)
      • 190
        A Novel Radioxenon Event Classification Method Based on CatBoost

        Four technologies are used for compliance verification of the comprehensive Nuclear-Test Ban Treaty (CTBT), hydroacoustic, infrasound, seismic and radionuclide monitoring. Forty radionuclide stations will have the radioxenon monitoring capability. For the last few years, a lot of research have been done in order to discriminate radioxenon derived from an explosion and anthropogenic sources. The explosion data are rare, for quite few nuclear test were done and little radioxenon was released from the underground. The civil facilities also emit mounts of radioxenon and the stations near those facilities will have a high radioxenon background. It is difficult to discriminate the background events and background plus explosion events. In this work, radionxenon monitoring data sets were modelled based on International Monitoring System xenon monitoring data over the past decade and the xenon ratios emitted by nuclear explosion. Dozens of features, including the four radionxenon concentrations, flags on xenon detected, xenon ratios, were analysed. We used CatBoost algorithm to establish a two classification model.

        Speaker: Mr Yungang Zhao (CTBT Beijing National Data Centre and Beijing Radionuclide Laboratory)
      • 191
        Interactive Analysis Prospective on Implementation of the NET-VISA in the International Data Centre Bulletin Production

        Data from the International Monitoring System (IMS) stations of the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) are being processed by automatic processing, Global Association, interactively analysed and reviewed, resulting in International Data Centre (IDC) bulletins. The Network Processing Vertically Integrated Seismic Analysis (NET-VISA) is a Bayesian seismic monitoring system designed to process IMS data to reduce the number of missed and false events in the automatic processing. NET-VISA has been implemented in operation as an additional event scanner in operation since January 2018. In this study we assess the effect of NET-VISA automatic scanner on the number of events in the IDC bulletins, Late Event Bulletin (LEB) and Reviewed Event Bulletin (REB). In particular, the impact of NET-VISA scanner on the number of scanned events during the interactive analysis is assessed. We use three distinct time periods to evaluate the NET-VISA performance as well as the effect of the other possible factors, such as global seismicity and network performance. The results show a 4.6% increase in the number of LEB events after including the NET-VISA scanner in operation, with an average of seven events per day and a notable increase of 17.90% in the number of scanned events.

        Speaker: Mr Sherif Ali (CTBTO Preparatory Commission)
      • 192
        Root Mean Square Lg Amplitude Measurements for the Democratic People's Republic of Korea Underground Nuclear Tests

        We determined root mean square (RMS) amplitudes of Lg waves from the six known underground nuclear tests conducted by the Democratic People’s Republic of Korea. We analysed waveform data from a dozen seismographic stations situated in the Republic of Korea, the People's Republic of China and the Russian Federation operated by the International Monitoring System, Global Seismic Network, and the Korea Meteorological Administration. The RMS Lg amplitude measurements indicate consistency between the stations situated in the continental crust. The measured RMS Lg amplitude at pairs of stations shows stability with an interstation standard deviation of as low as 0.03 magnitude units for the six explosions. The RMS Lg amplitude measurements on vertical records are well correlated to the teleseismic body wave magnitude mb of the six explosions with a very small standard deviation ranging from 0.03 to 0.08 magnitude units. The stability of RMS Lg amplitudes suggests that it can be used to estimate the yield of the Democratic People’s Republic of Korea's nuclear tests.

        Speaker: Mr Won-Young Kim (Lamont-Doherty Earth Observatory, Columbia University)
      • 193
        Radioxenon Isotopic Composition of Release Scenarios Based on Realistic Models of Underground Nuclear Explosion Cavity Evolution and Subsurface Gas Transport

        Isotopic ratios of radioxenons can be used to verify the occurrence of an underground nuclear explosion (UNE). Simplified analytical models and closed-form solutions using Bateman equations simulate a idealized radioactive decay/ingrowth chain in a closed and well mixed system. The partitioning of the radionuclide inventory between a gas phase and rock melt created by the detonation and the gas transport from the cavity to host rock or ground surface are not addressed properly. Either subsurface transport or prompt release that is principally responsible for gas signatures are inconsistent with the simple closed-system assumption. In this study, a realistic model about post-detonation cavity processes were developed. A closed-form solution representing time dependent source term activities is extended by considering the cavity partitioning process, slow seepage, and/or prompt release of gases from the cavity and applied to realistic systems, influencing the evolution of isotopic ratios over the course of UNE histories. A library of radioxenon composition in the cavity and host rock can be simulated with different parameters, which is used for event discrimination and further for estimation of the detonation time with respect to noble gas measurements at International Monitoring System stations. It can also be used for the event discrimination based on machine learning.

        Speaker: Mr Boxue Liu (CTBTO Preparatory Commission)
      • 194
        Impacts on Characterization of a CTBT-Relevant Nuclear Event Using Isotopic Ratios Caused by the Radioxenon Background Subtraction at International Monitoring System Stations

        Radionuclide stations in the International Monitoring System (IMS) network routinely collect air samples and assess activity concentrations. Activities collected in samples are often caused by emissions from nuclear facilities, but they could also indicate a noble gas release from an underground nuclear explosion. A discrimination can be done by estimating and analysing activity ratios of CTBT-relevant radioxenon isotopes under assumed scenarios. One of the issues in the isotopic ratio estimation is whether the contribution of the radioxenon background at IMS stations needs to be subtracted. This work will investigate the impact of the radioxenon background subtraction on the discrimination of a nuclear release event. Simulations are performed with atmospheric transport modelling to determine the concentrations originating from hypothetical radioxenon releases of pre-defined underground nuclear explosions distributed over a global semi-regular grid at different times of the day. The latter are studied independently and in the form of synthetic concentrations on top of real observations to account for the radioxenon background. The ratios of detected radioxenon isotopes are compared between the real IMS observations (typical radioxenon background from 2014), simulated concentrations from hypothetical nuclear explosion sources (pure signals without radioxenon background) and synthetic ones.

        Speaker: Mr Boxue Liu (CTBTO Preparatory Commission)
      • 195
        Joint Regional Waveform, First Motion Polarity, and Surface Displacement Inversion Using a Layered Elastic Model with Topography for the People’s Democratic Republic of Korea Nuclear Explosions

        On 7 September 2017, the Democratic People’s Republic Korea carried out its latest and largest nuclear test (DPRK6). Recent efforts have been made to increase understanding of this and previous nuclear tests using seismic waveform, and synthetic aperture radar (SAR) geodetic deformation data (e.g. Wei 2017, Chiang et al. 2018, Myers et al. 2018, Wang et al. 2018). In our previous work (Chi-Durán et al. 2021) we performed a joint regional waveform, first-motion polarity, and surface displacement inversion demonstrating improved discrimination of the source type of the event. In this work, we have applied the aforementioned joint inversion with a layered velocity model based on satellite observations of discontinuities and inferred lithology (e.g. Pabian and Coblentz, 2015) and published ranges of seismic velocity for the inferred lithology to DPRK6 and an earlier event (DPRK4, 2016/01). We find that the consideration of the layered velocity model improves the recovery of source depth, and in both cases the joint inversion is found to provide better discrimination of the source type and better constrain the scalar seismic moment needed for downstream yield estimation.

        Speaker: Rodrigo Chi-Durán (University of California, Berkeley)
      • 196
        Improvement of Methods for Characterizing CTBT-Relevant Radionuclide Events Based on Data from the Temporary High Density Network Formed by the International Monitoring System Noble System JPX38 and the two Transportable Radioxenon Measurement Systems

        Since 2008, the CTBTO has been conducting temporary radioxenon measurement campaigns using transportable systems. These campaigns are focused on improving the performance of the verification system as described in the Treaty. In 2017, the Government of Japan made a voluntary contribution to boost CTBTO capabilities to detect nuclear explosions. In early 2018, two transportable noble gas systems were deployed in Japan where they form, together with the International Monitoring System (IMS) system JPX38, a high density network. As of today a few thousand samples have been measured by the two transportable systems. Measurement spectra are automatically sent to the International Data Centre, processed in a non-operational database and reviewed with focus on the four CTBT-relevant xenon isotopes. Reviewed data are used to improve methods and methodologies for understanding the radioxenon background that are applicable to any IMS noble gas system. Possible sources regions (PSR) and evolution consistency of isotopic ratios in samples collected by the systems forming the high density network were estimated first, and the impact on isotopic ratio consistency and on both standard and consistency specific PSRs was investigated. Further applications include isotopic ratio screening, Xe-135 observations, and enhancements of concentration estimates from known sources.

        Speaker: Jonathan Bare (CTBTO Preparatory Commission)
      • 197
        Seismic Data Analysis for the Discrimination, Detection, and Location of Seismic Events of the People’s Democratic Republic of Korea

        The main purpose of this study consists in applying discrimination methods to distinguish known nuclear tests conducted by the Democratic People’s Republic of Korea from surrounding natural seismicity, based on various seismic signal processing algorithms. To characterize the Democratic People’s Republic of Korea's seismic activity between 2006 and 2022, spectral analysis, waveforms cross-correlation techniques and amplitude ratios of Pg/Lg and Pn/Sn waves computed in different frequency bands were applied. For the selected events, we analysed waveforms recorded by seismic stations with epicentral distances going up to 70 degrees. The Democratic People’s Republic of Korea's nuclear tests were relocated using relative algorithms to validate and calibrate these methods. Additionally, we investigated continuous recordings of nearby stations (epicentral distances below three degrees) using waveforms cross-correlation techniques to identify possible microearthquakes induced by the the Democratic People’s Republic of Korea's nuclear tests. The proposed discriminants successfully separate tectonic events from nuclear tests, but its success rate is heavily influenced by the epicentral distance. The relocations of the Democratic People’s Republic of Korea's nuclear tests showed differences of up to 5 km compared to the results of previous studies, highlighting a good accuracy of the proposed methods. These findings represent the first step in the development of future artificial intelligence algorithms.

        Speaker: Iulia Stefania Armeanu (National Institute for Earth Physics (NIEP))
      • 198
        The Rock Valley Direct Comparison instrumentation plan

        The Rock Valley Direct Comparison (RV/DC) project is the third phase of the Source Physics Experiment (SPE). Under RV/DC, two chemical explosions will be detonated near the hypocenters of a sequence of anomalously shallow earthquakes on the Nevada National Security Site. The explosions (nominally 1,000 and 10,000 kg TNT-equivalent) will be recorded by an extensive array of multi-physics sensors. This will be the first direct comparison of earthquake and explosion signatures originating from nearly identical hypocenters. The direct comparison will enable researchers to exploit the physical differences between explosion and earthquake sources sharing the same propagation path and recording sensors.
        Here, we present the multi-physics sensor network we plan to deploy, which includes seismic, infrasound, distributed fiber optic and GPS stations. These instruments will be deployed on the Earth’s surface, in deep boreholes, and on aerial balloon platforms. A full distribution of propagation ranges will be covered, from near-source (tens of meters), to regional (hundreds of kilometers) distances. We anticipate these signals will provide key metrics in next generation monitoring systems.

        Speaker: Mr Robert Abbott (Sandia National Laboratories (SNL))
      • 199
        Kazakhstan IMS Stations Recording the Quarry Blasts Conducted on the Territory of the Former Semipalatinsk Test Site

        On the Semipalatinsk Test Site territory there are several mineral deposits at some of which the active mining is observed. The most blasts are conducted at Karazhyra coal quarry. Three IMS stations, Makanchi (PS23), Borovoye (AS057), Kurchatov-Cross (AS058), are recording these quarry blasts. The quarry-to-stations distance is 452 km, 668 km, and 68 km respectively. For 19 years of observation, about 2800 quarry blasts were recorded. The analysis of the routine processing results from the automated and interactive bulletin of Kazakhstan NDC showed that the field of obtained epicenters exceeds the quarry size. To understand the reasons of such scatter, the waveforms were processed in detail. For the processing and analysis of the waveforms, Geotool and DTK – GPMCC software were used. It was revealed that the azimuths values of different regional phases Pn, Pg, Sn, Lg differ from each other and have different dispersion. There are systematic deviations of azimuths for some phases. The clear dependence of the epicenter accurate measurement on energy (yield) of blasts was noted. The human factors influencing on the estimations accuracy were also found. The recommendations on processing were given to the KNDC analysts to improve location accuracy and discriminations of seismic events.

        Speaker: Mr Aidyn Mukambayev (National Nuclear Center of the Republic of Kazakhstan)
      • 200
        The Central and Eastern European Infrasound Network

        We introduce the Central and Eastern European Infrasound Network (CEEIN) established in 2018 as a collaboration between the Zentralanstalt für Meteorologie and Geodynamik, Vienna, Austria; the Institute of Atmospheric Physics of the Czech Academy of Sciences, Prague, Czech Republic; the Research Centre for Astronomy and Earth Sciences of the Eötvös Loránd Research Network, Budapest, Hungary; the National Institute for Earth Physics, Magurele, Romania and the Main Centre of Special Monitoring National Center for Control and Testing of Space Facilities, State Agency of Ukraine. Waveform data of the CEEIN stations are archived at the NIEP EIDA node, and can be downloaded from www.ceein.eu.
        We demonstrate that CEEIN improves infrasound event detection capabilities in Southern and Eastern Europe, and show that adding infrasound observations to seismic data in the location algorithm improves location accuracy. We identify coherent noise sources observed at CEEIN stations. We present the biannual CEEIN bulletin of infrasound and seismo-acoustic events, our contribution to the European infrasound catalogue. Many of the events in the CEEIN bulletin are ground truth events that can be used in the validation of atmospheric models.

        Speaker: Mr Istvan Bondar (Research Centre for Astronomy and Earth Sciences (ELKH))
      • 201
        Registration of Exogenous Phenomena by Seismic Stations in Kyrgyzstan

        The National Data Center of Kyrgyzstan daily monitors seismic events of various nature, most of which are tectonic earthquakes and quarry blasts. Sometimes seismic stations in Kyrgyzstan register unusual phenomena associated with exogenous geological processes, such as landslides, snow avalanches, rockfalls and mudflows. Landslides and snow avalanches can be caused by both tectonic processes and geological, geomorphological and hydrogeological conditions, climate change, as well as the impact of a complex of anthropogenic factors. According to the records of Kyrgyzstan’s seismic networks the features of the waveform of a powerful landslide on November 30, 2019 ~23-43 GMT in the area of the Kumtor gold deposit were studied, the volume of which was 12.825 million cubic meters. The waveforms of another landslide on September 14, 2020 in the area of the Kara-Keche coal deposit with a volume of ~1 million cubic meters were studied. As well as seismic records of a glacier retreat with a volume of ~2 million cubic meters in the area of the Juuku gorge on July 8, 2022 ~08-44. It is shown that landslides in the areas of the Kara-Keche and Kumtor deposits are caused by anthropogenic activity, and the glacier collapse is caused by climate change.

        Speaker: Ms Elena Pershina (Institute of Seismology, National Academy of Sciences of the Kyrgyz Republic)
      • 202
        Seismic Events in Central Kazakhstan According to the Monitoring Network of the National Nuclear Center of the Republic of Kazakhstan

        Over the past ten years of observations by the seismic monitoring network of the National Nuclear Center of the Republic of Kazakhstan, seismic events of a different nature have been registered on the territory of central Kazakhstan. The largest number of these events are quarry explosions at deposits of solid minerals. But there are also tectonic earthquakes and natural-technogenic events induced by prolonged explosive activity in the field. Despite the fact that earthquakes are rarely recorded in such ‘weakly seismic’ areas, quite strong earthquakes can occur there, causing damage to the existing infrastructure near their sources. The paper presents materials on the study of the nature of seismic events and their interrelations with the deep structure of the environment, the tectonics of Central Kazakhstan and the distribution of anomalies of geophysical fields.

        Speaker: Mr Abylay Uzbekov (National Nuclear Center of the Republic of Kazakhstan)
      • 203
        Military Depot Bursts in the South of Kazakhstan and Uzbekistan by Data of Kazakhstan Monitoring Network Stations

        In recent years there were several tragic accidents at military depots in the south of Kazakhstan (Arys, Taraz) and in Uzbekistan (Malik) resulting in destruction of buildings, injuries and loss. All these bursts were recorded by Kazakhstan seismic stations. The closest station to the epicenters of all bursts was Karatau seismic array, part of the National Nuclear Center monitoring system of the Republic of Kazakhstan. Using the data of this station, the explosions were located, energy parameters were calculated and the waveforms were analysed in detail. Each of the three cases had a different “scenario” of explosion sequence. In Arys, there were more than 30 bursts with energy class (K) ranging from 4.8 to 7.8. In Taraz there were 17 bursts, with K value ranging from 4.3 to 8.1. In Uzbekistan there was one explosion with K=7.8. The wave pattern and spectral density were analysed using the f-k analysis, DTK – GPMCC, Geotool. The knowledge of the exact epicenter location of the bursts allowed them to be considered as ground-truth events. The location accuracy of different bursts using the data of one seismic array was estimated. The regional travel-time curve of seismic waves for south Kazakhstan was specified.

        Speaker: Mr Nurbek Seinassinov (National Nuclear Center of the Republic of Kazakhstan)
      • 204
        Evaluation of Nordstream Explosions Using NDC in a Box Software

        Two seismoacoustic events occurred on 26 September 2022 close to Bornholm Island in the Baltic Sea. Both events were listed in the Reviewed Event Bulletin of CTBTO as they were detected with the International Monitoring System. As the events were classified as a critical event by the Austrian National Data Centre, the available data were analysed in detail. The earlier event, with a published body wave magnitude mb 3.1, at 00:03 UTC was recorded at three seismic stations and at the infrasound station IS26. The later event at 17:03 UTC with a body wave magnitude mb 3.2 was even recorded at seven seismic stations and at the two infrasound stations IS26 and IS43. Furthermore, the later event was detected at the Austrian infrasound station ISCO.
        A first assessment of data, which were analysed by using the DTK-GPMCC, confirmed the explosive nature of the events due to extraordinary infrasonic detections. Further analysis was carried out using waveform analysis tools available within NDC in a box (GeotoolQt and Geotool). Seismic data of the events from 26 September 2022 were compared with data of a natural seismic event which occurred in Croatia on 1 October 2021 and the explosive character of the events could be confirmed.

        Speaker: Ms Ulrike Mitterbauer (GeoSphere Austria)
      • 205
        Constraining Moment-Tensor and Source Depth of a Mine Quake Using Local Infrasound Data

        Previous works have demonstrated potential in using infrasound data to constrain earthquake source properties (Hernandez 2016; Shani-Kadmiel 2018, 2021; Averbuch 2020). Typically, the applied approaches are based on comparing modelled and recorded signals. In the current study we seek to constrain the source depth and moment-tensor. We use infrasound data from local and seismic data from local and regional stations. We use the data from the Kiruna 2020 mine quake of which the local and regional recorded infrasound signatures have been presented at previous venues. This event is one of the largest Scandinavian mining-induced earthquake. It produced signals recorded by three infrasound arrays at distances of 7 km (KIR), 155 km (IS37) and 286 km (ARCI). Our recent studies show: (1) Full moment-tensor estimated from the seismic data, and source-type analysis shows that this event has collapse features. (2) Data simulation comparison of seismoacoustic data for various possible source depths using SPECFEM-DG concludes that the local infrasound data helps estimating source depths. (3) Comparison of simulated infrasound signals using full moment tensor solution estimated in this study and the full moment tensor solution from GCMT showed that our full moment-tensor solution produces infrasound signals having a better agreement with the observations.

        Speaker: Antoine Turquet (Norwegian Seismic Array (NORSAR))
        v1
      • 206
        Open Access Products from International Monitoring System Infrasound Bulletins for Atmospheric Science Applications

        We introduce infrasound data products of all certified International Monitoring System infrasound stations for scientific studies and applications. We have reprocessed the IMS infrasound waveform data of the last 20 years using the Progressive Multi-Channel Correlation (PMCC) method, configured with one-third-octave frequency bands between 0.01 and 4 Hz. From the comprehensive detection lists we derived four products for each of the 53 stations. These cover different frequency ranges and temporal resolutions, and thus different sources. The low-frequency product (0.02–0.07 Hz, 30 min) primarily covers mountain-associated waves. The second product mainly reflects the spectral peak of microbaroms (0.15–0.35 Hz, 15 min). Higher frequencies of microbaroms and other sources are summarized in the third product (0.45–0.65 Hz, 15 min). Observations with centre frequencies of between 1 and 3 Hz (5 min) are part of the high frequency product. Our intention for these data products is to facilitate using this unique global infrasound dataset for scientific applications. The products open up the IMS observations to user groups who do not have access to IMS data or are unfamiliar with data processing using the PMCC method. We demonstrate the data products based on recent and global atmospheric infrasound sources, such as volcanic eruptions and ocean ambient noise.

        Speaker: Patrick Hupe (Federal Institute for Geosciences and Natural Resources (BGR))
      • 207
        A Collection of Romanian Infrasound Observations from Ground Truth Sources

        Starting with 2009, three infrasound stations have been deployed on the Romanian territory by the National Institute for Earth Physics: (1) IPLOR (in central Romania), (2) BURARI (in northern Romania) – under cooperation with AFTAC (USA), and (3) I67RO temporary PTS portable array (in western Romania) as a two-year experiment (2016-2018), within a collaboration project with the Provisional Technical Secretariat. Data recorded with these stations are continuously processed and analysed at theRomanian National Data Centre by running a duo of infrasound detection-oriented software – DTK-GPMCC and DTK-DIVA – packaged into NDC in a box. A significant set of detected infrasound signals could be associated to ground truth events located by the International Data Centre (REB, LEB) and seismological centres (EMSC, ISC). Further details were obtained from the fireball database published by CNEOS/JPL. The main types of ground truth sources observed with Romanian infrasound arrays are bolides, earthquakes, chemical/accidental/military explosions, volcanic eruptions, and anthropogenic activity (mining, sonic booms). Collected information summarizes the ground truth source, Romanian infrasound stations detecting the event, predicted infrasound arrivals, associated infrasound detections, and detection plots related to the event, and is accessible via HTML interface. The geographical distribution of the ground truth events can be plotted with Google Earth software using a KML file containing the location of the events.

        Speaker: Ms Daniela Ghica (National Institute for Earth Physics (NIEP))
      • 208
        Acoustic Signal Identification of Submarine Seismic

        International Monitoring System H phase stations have great potential for submarine earthquake monitoring in the southern hemisphere. The hydrophones could record low frequency sounds from extensive areas. However, some seismic signals from different areas would have similar characteristics in a short time interval. It is difficult to locate the epicenter using only the azimuth and arrival time from the hydrophone triplet. Therefore a submarine seismic location model was built based on the time delay of the P-wave and T-wave at a hydrophone to obtain the sound propagation distance. Arrival times were extracted based on the Akaike information criterion. Combined with the back azimuth, the event time and location could be acquired via a single triplet. Furthermore, the proposed method is applicable to the identification of hydrophone signals under the informed seismic bulletin. The correspondence between signals and earthquakes contributes to the construction of AI algorithmic datasets for seismic signal detection. Over 940 submarine earthquakes (≥M 4.0) were located using the proposed method, and the locations were verified by using the USGS bulletin which were recorded from 2014 to 2020 by two hydrophones triplets of International Monitoring System hydroacoustic station HA3 located at the Juan Fernandez Islands.

        Speaker: Shiyan Wei (Third institute of oceanography, Ministry of natural resources)
      • 209
        Systematic Event Analysis of International Monitoring System Hydrophones to Identify and Categorize Hydroacoustic Sources

        In this study we aim at discriminating hydroacoustic sources by identifying on the one hand source typical signal features derived from event catalogues and by characterizing on the other hand waveform similarities using clustering analyses of raw hydroacoustic data. We make use of event bulletins derived from the application of the Progressive Multi Channel Correlation method on International Monitoring System hydrophone data and from Reviewed Event Bulletin (REB) entries with hydrophone stations involved. We apply a general source discrimination by quantifying signal parameters like frequency content, time duration, waveform shape and signal amplitude and categorize sources using previously identified signal properties from literature. We further compare the raw waveforms of International Monitoring System hydrophone data during time segments of event detections and apply clustering analyses to separate waveform families by their similarity to each other and to certain reference events. We also suggest to include additional information from propagation modelling, bathymetry and ocean conditions to explain the observed event signatures and to connect them to different hydroacoustic sources and source regions. We finally compare our results with other approaches on signal discrimination and classification and try to estimate the precision and sensitivity as well as general feasibility and usefulness of our method.

        Speaker: Dr Christoph Pilger (Federal Institute for Geosciences and Natural Resources (BGR))
      • 210
        ParMT – Parallel Software for Shallow Seismic Events Joint Moment Tensor, Depth and Magnitude Determination

        The International Data Center is required to conduct expert technical analysis (ETA) and special studies to improve event parameters and assist States Parties in identifying the source of specific events, according to the Protocol to the Comprehensive Nuclear-Test-Ban Treaty. Source mechanism and event depth are two parameters which may be crucial for the event discrimination task. To introduce them into the Provisional Technical Secretariat commissioning, we have conducted testing and tuning of the ParMT branch of the SHI-ETA suite. The ParMT software is a new tool for shallow seismic event depth determination and source parameters characterization. Source properties are estimated via grid search over moment tensors. We follow Tape and Tape (2015) to uniformly discretize the moment tensor space, then determine the optimal moment tensor, magnitude and depth by comparing observed seismograms with synthetic waveforms. The software solves for the moment tensor for major types of sources (ISO, DC, CLVD) and source-receiver distances, as well as for the observed body and surface waves. A powerful user interface is included providing the whole analyst work cycle, from picking arrivals and polarity to final report generation. For ETAs, International Monitoring System as well as non-International Monitoring System data can be jointly used in processing.

        Speakers: Mr Mikhail Rozhkov (Instrumental Software Technologies, Inc. (ISTI)), Mr Ivan Kitov (CTBTO Preparatory Commission)
      • 211
        International Monitoring System Portable Infrasound Array in Côte d’Ivoire: Opportunity to Study Local and Regional Infrasound Sources

        The National Data Centre of Côte d’Ivoire and the PTS installed a portable infrasound network (I68CI) from mid-January to December 2018 in the Comoé National Park located in north-east Côte d’Ivoire. This mobile station includes four sensors and use MB3d microbarometers with 50 Hz sampling frequency. The main objective of this one-year deployment is to better understand and characterize regional infrasound sources. Some regional and local infrasound sources are detected by both a mobile array (I68CI) and a fixed array (I17CI). Among these sources, we note Mbembele (Mali) and Tongon (Côte d’Ivoire) mine activities. Hydroelectric power dam (Buyo, Soubre and Taabo) activities are also detected in Côte d’Ivoire. The split characteristics of the tropical Mesoscale Convective System of 9 April 2018 in northern Ghana is also investigated using the mobile array (I68CI) measured data.

        Speaker: Komenan Benjamin Kouassi (Station Geophysique de Lamto)
      • 212
        Investigation of the P/S Discriminant at Local Distances Using Simulated Waveforms

        The impact of wave propagation effects on the performance of the P/S ratio local discriminant is being evaluated during the third phase of the Source Physics Experiment, the Rock Valley Direct Comparison (RV/DC), conducted at the Nevada National Security Site. During the experiment a chemical explosion will be detonated near the hypocenter of a shallow earthquake. The direct waveform comparison on a dense network of seismic sensors will enable the investigation of seismic source signatures and discrimination between explosion and earthquakes sharing the same propagation path. We used high-frequency (0-10Hz) ground motion simulations to emulate the RV/DC experiment in order to investigate the generation and propagation of seismic waves at local distances, and the performance of the P/S source discriminant. The numerical experiments were performed using high-performance computing and a local velocity model with correlated depth-dependent stochastic velocity and density perturbations, that are needed for simulating wave scattering on a frequency range of monitoring interest. We found that at local distances the P/S discriminant is strongly affected by the degradation of the radiation pattern of source generated P and S waves due to wave path effects in the shallow crust, and that network averaging improves the overall discriminant performance.

        Speaker: Mr Arben Pitarka (Lawrence Livermore National Laboratory (LLNL))
      • 213
        Full Moment Tensor and Source Characteristics of Nuclear Explosions at the Lop Nor Test Site, China

        We investigate historical nuclear tests from the Lop Nor region, China, using waveform-based source inversions and three-dimensional waveform modeling. Despite sparse data distributions and low signal-to-noise ratios, we recover isotropic moment tensor solutions for historical explosions and obtain detailed uncertainty information from likelihood evaluations over magnitude, depth, and the entire space of moment tensor source type and orientation parameters. We identify a one-dimensional (1-D) Western China Earth model that provides improved waveform fits, reduced cycle skipping, and drastically improved uncertainty estimates compared with spherical-average Earth models. Preliminary 3-D forward modelling results show yet further promise for improving source constraints. By exploring the entire source parameter space, we account for tradeoffs that become important for the determination of source type, depth of burial, and yield in sparse monitoring scenarios. Subsequent likelihood-based uncertainty analysis shows the importance of accounting for differences in data variance between body waves, Rayleigh waves, and Love waves and allows for straightforward data fusion between waveform, travel time, and polarity measurements.

        Speaker: Mr Jonas Kintner (Los Alamos National Laboratory (LANL))
      • 214
        The Infrasound Reference Event Database Needs to be Revised

        The International Monitoring System (IMS) of the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) comprises four verification technologies that work in synergy to enable the detection, location, and identification of potential nuclear explosions. One of the four technologies is the infrasound which listen to corresponding sound waves. As of 2022, Fifty-three from sixty planned IMS infrasound stations are recording corresponding pressure fluctuations. In this regard and in order to support the National Data Centres (IDC ) and infrasound analysts, the IDC produced on 9 July 2010 the Infrasound Reference Event Database (IRED) to collect, review and document infrasound events of special interest and to archive the data for each event into database tables to be used for training, testing and validation purposes. IRED contains 616 events grouped in 12 categories. In the last 12 years, infrasound stations detected more events of special interest which can be added to the database. New infrasound stations were certified after 2010 and recorded more interesting events. Moreover, some existing events in IRED need to be corrected. In this poster we will show that IRED needs to be revised and updated using existing events from the database and some new detected events.

        Speaker: Dr Abdelouaheb Agrebi (Former CTBTO Preparatory Commission)
      • 215
        Improving Localization of Mining Activities Using Infrasound and Seismic Data: A Case for I35NA and I47ZA

        Seismological bulletins from local and regional seismic stations have identified signals associated with mining explosions in the Orapa mining area, Botswana. Here we present the results of integrating detections from regional seismic networks and the International Monitoring System (IMS) network. Using the local bulletins and catalogs, we requested IMS data via the Extended NDC-in-A- Box (ENIAB) and retrieved local station data using the Obspy library. The combined analysis of seismic and infrasound signals gave additional information about the origin time and location of events as well as distinguishing mine explosions from natural events. Infrasound detections were generated using the ENIAB’s DTK-GPMCC whereas Geotool was used to analyse seismic data. Geotool was also used to create a final integrated bulletin. Combining the infrasound stations of IS47 (South Africa) and IS35 (Namibia) with the local seismic stations improved the location of these seismoacoustic events.

        Speaker: Onkgopotse Ntibinyane (CTBTO Preparatory Commission)
      • 216
        Volcano Seismology in Afar and the Northern Main Ethiopian Rift (MER): Potential Sources for Ground Truth Events

        Hundreds of years has elapsed since earthquakes started to be instrumentally recorded. However, our understanding of magmatic rifting and other complicated source features that we observe today was limited due to the absence of digital seismic records at epicentral distances of interest. After the advent of digital broadband instrumentation with wide dynamic range, volcano seismology has become one of the strongest disciplines contributing to the study of magmatism. Over 20 volcano-tectonic earthquake sequences have occurred in Afar and the northern main Ethiopian rift for the last couple of decades and the corresponding seismic data are recorded by temporary and permanent broadband seismic network. This shows that there are several active volcanic and fissure eruptive centers in the area which need monitoring to study continental rift mechanisms and for mitigating volcano and earthquake hazards. Moderate size earthquakes from these active volcanoes can be used as a reasonable ground truth event so as to improve the regional travel times curves.

        Speaker: Prof. Atalay Ayele (Addis Ababa University (AAU))
      • 217
        Studies on Infrasound Technology Applied to the Discrimination of Chemical Explosions From Tectonic Events

        This work has the goal to present a useful method to help in the discrimination of natural events (tectonics) from artificial events (chemical explosions in quarries blasting) when both sources are co-located. This is a frequent problem where the seismicity is triggered by stress released due to material removal in mines. With that purpose, we are conducting experiments using local infrasound stations to monitor blasting in quarries, recording infrasonic signals from detonations and infrasonic signals generated by earthquakes, in case they are present. Our work is done considering two scenarios, one of them using one co-located seismic and infrasound stations installed where there are blasting in mines and natural events (up to 30 km distant). We have already managed to get some results with this configuration. The other scenario we are in our way to implement two infrasound arrays (triangular shape four elements each) and a seismic network where there are blasting in mines and natural events. This implementation will be done soon. Our initial findings is that the few induced earthquakes occurred at a mining open pit did not produce any detectable infrasonic signal, hence we managed to discriminate them from the mining blast occurred at the same spot.

        Speaker: Mr Darlan Portela Fontenele (University of Brasilia, Seismological Observatory)
      • 219
        Analysis of the North Stream Underwater Blasts in the Baltic Sea on 26 September 2022

        On 26 September, 2022 the International Monitoring System (IMS) detected two seismic events near the Danish island of Bornholm. The events were seen in both seismic and infrasound data and were located near the positions where large gas leaks from the North Stream were later observed. The events were furthermore recorded by seismographs in the surrounding countries and analysed at the National Data Centres. The waveforms exhibited clear properties of underwater blasts with significant P energy and much smaller S- energy, as well as other characteristics not associated with natural earthquakes. Further analysis revealed that particularly the second event may consist of multiple blasts close in time and space. Analysis of the events included integration between IMS data and regional data from Denmark, Sweden, Germany and Norway, and served as an exercise in collaboration during an international crisis.

        Speaker: Tine Larsen (Geological Survey of Denmark and Greenland (GEUS))
      • 220
        Seismoacoustic Listening of a Baltic gas Explosion

        This study provides an overview of a civil application of International Monitoring System (IMS) data to assist in disaster mitigation. Two infrasound arrays coupled with seismic stations of the IMS recorded the with Baltic Sea gas explosion on 26 September 2022. Underwater eruptions generate air waves and pressure waves that can cause fluctuations in the different layers of the atmosphere. Analysis of the event was done using GPMCC to test the operational readiness of these IMS stations. The parameters studied were phase, frequency, magnitude, azimuth and slowness which were observed to be consistent with theoretic values. The combined interpretation of seismic and infrasound signals was used to obtain the location of the event. The study concludes that at local and regional distances the IMS network is operational ready in a timely manner to contribute data towards a safer environment.

        Speaker: Mr Uchenna Onwuhaka Madu (Nigeria Atomic Energy Commission, Abuja)
      • 221
        The Reviewed Event Bulletin and the Standard Event List 3 Bulletin for CPUP Scope Measurement

        Paraguay, located in the middle of South America, is a low seismicity country. Nevertheless it has been collecting data for a long time. The continuous operation of the station gives us the opportunity to select several years of bulletin. This time five years of International Data Centre (IDC) detection (from 2018 to 2022) were selected from bulletins (reviewed and automatics) that are used to breakdown the scope of the sensor detections and show the distribution of epicenters, which CPUP have been contributing to the IDC. The main purpose of this presentation is to illustrate in general how quantitatively the station has been used for global detection.

        Speaker: Mr Alcides Caballero (Universidad Nacional de Asunción)
      • 222
        Possible GT5 Events in Costa Rica

        Starting in 2010, when the OVSICORI-UNA seismic network was upgraded with 24-bit digitizers and broadband instruments, we selected possible candidates to GT5.0 seismic events from the seismic catalog.
        The GENLOC program was used to locate the events and the selection criteria were as follows: 1) minimum number of stations greater than or equal to 30, 2) Gap less than 110 degrees, and 3) minimum number of stations within 30 km greater than or equal to 1. In total, 707 events were selected.
        The selected events are mostly in the central part of Costa Rica, with magnitudes between 1.9 and 6.0 Ml and depths ranging from 0 to 200 km.

        Speaker: Ronnie Quintero (Observatorio Vulcanológico y Sismológico de Costa Rica, Universidad Nacional (OVSICORI-UNA))
      • 223
        Cambronero Landslide on 17 September 2022, 16:10 Local Time Costa Rica

        Landslides along the Inter-American Highway in Central Costa Rica, between San Ramon and Esparza are common, mostly during rainy season and are more related to instability due to the state of alteration of the materials on the slopes than to local faults. The saturation of the soil and the slopes could lead to the acceleration of these landslide processes even with earthquakes of moderate magnitude. These earthquakes could occur both on the upper-crust faults, and along the subduction zone on the Pacific coast. Seismic local catalogue for the zone shows that earthquakes of low magnitude had been located nearby, being the earthquake of 20 December 2005, at 09:00:45, Ml 3.9 the largest. On 17 September at 4:10 p.m. Costa Rican time, the Costa Rica emergency system was informed of a bus accident in Los Chorros de Agua, Cambronero, Santiago de San Ramon, caused by a landslide, where several persons died. Although the landslide was small in dimension, it was detected by an infrasonic station, located on Poas Volcano ~36 km from the source and shows that infrasound station, as is this case, can be used to characterize small landslides, among other local infrasound sources.

        Speaker: Ronnie Quintero (Observatorio Vulcanológico y Sismológico de Costa Rica, Universidad Nacional (OVSICORI-UNA))
      • 224
        Geophysical Monitoring System Interactive Analysis Capabilities

        Sandia National Laboratories is developing the Geophysical Monitoring System (GMS) for modernization of the United States National Data Center waveform processing system. The United States is providing the common architecture and processing components of GMS as a contribution in kind to accelerate progress on International Data Centre (IDC) re-engineering. Open source releases of GMS, available on GitHub, have been made annually since 2018. Recently the GMS development effort is focused on interactive analysis capabilities, referred to as IAN. The 2022 GMS open source release includes capabilities to access and display station metadata, waveforms, signal detections, and events (QC mask display is also in development). IAN uses modern web technology, accessed with a common web browser. All displays are fully synchronized with a consistent user experience. The 2022 release also includes a mature, operational quality station state of health (SOH) monitoring capability for CD-1.1 protocol stations, to enhance the ability of system operators to quickly recognize and address station availability and quality issues. GMS is deployed using a cloud-ready Kubernetes containerized platform, hardened for cyber security accreditation. This presentation describes the current GMS interactive analysis and station SOH monitoring capabilities.

        Speaker: James Mark Harris (Sandia National Laboratories (SNL))
      • 225
        Seismic, Hydroacoustic and Infrasound Monitoring for Seismic Stations Applying 3G/4G Technologies

        The Observatorio San Calixto (OSC) is the National Data Center for the Plurinational Bolivian State. It manages the certified seismic stations PS06-LPAZ, AS08-SIV and one infrasound array IS08-BO. The distances from our center to the far away seismic station is about 1000Km (AS08-SIV) and the other two are located at Altiplano where the environment to work is often hard. In order to obtain the state of health (SoH) from these seismic stations we built a low cost board based on embedded technology (RaspberryPi) that allow us to monitor the batteries voltages, temperature at cave, intrusion, hard-disk/USB space and sometimes works as data buffer. The source code is powered by Python and the decencies for the input/output are taken from RaspberryPi cloud, furthermore, we were able to send this information through the Internet using 4G dongle from local telecommunication company. Data is sent to the OSC by a VPN, this information is then stored in a small database powered by MySQL, the information is displayed for the operators each three or four minutes. This method is also used in the national seismic network to help the station operator to anticipate and solve problems.

        Speaker: Mr Felipe Condori Apaza (Observatorio San Calixto)
      • 226
        Radionuclide Station RN48 Installation by Local Skills: Niger Experiences

        The Comprehensive Nuclear Test Ban Treaty (CTBT) prohibits nuclear explosions by anyone, anywhere: on the Earth's surface, in the atmosphere, underwater and underground by using four key technologies such as radionuclide monitoring. Niger deposited its instrument of ratification of the Comprehensive Nuclear Test Ban Treaty (CTBT) with the Secretary-General of the United Nations on 9 September 2002, bringing the total number of ratifications to 94. Niger is the 14th State Signatory in Africa to ratify the Treaty. Under the terms of the Treaty, Niger is home to two International Monitoring System (IMS) facilities, a primary seismic station PS26 in Torodi and a radionuclide station RN48 in Agadez which is being coupled by SPALAX NEX48 noble gas. The RN48 radionuclide station was installed in December 2018 and certified on 26 August 2019. This poster we will describe the step by step the process of the installation and test phase, the certification process and the operations and maintenance carried out by local experts.

        Speaker: Mr Bawa Mamane (Haute Autorité Nigérienne à l'Energie Atomique (HANEA))
      • 227
        Decreasing Operational Costs by Enhancing Regional and Local Capabilities: A New Paradigm for Long Term Global Network Operations

        The IDA/GSN seismic network consists of 40 broadband seismic stations around the globe. Fifteen stations serve as auxiliary seismic stations of the International Monitoring System (IMS). During the COVID-19 pandemic, travel was severely disrupted. However, after considerable adjustment, network data return remained good and operational costs decreased. This was due to several factors: 1) decreased international travel by US based field engineers, 2) increased reliance on local operators to perform more complex operations and maintenance tasks and 3) increased spare equipment on site. Repairs and sensor replacements were conducted by either local station operators, local contractors, or in-country seismic technicians. Advanced training of local operators was based on improved documentation, sometimes with on-site video streaming using cell phone based applications. Difficulties included a wide range of time zones for the US based engineers and cross-language communication combined with sometimes poor audio quality. These difficulties were addressed by developing more extensive step by step documentation and communication improved over time. Benefits consisted of less travel and associated costs by the US engineers and increased capabilities by station personnel. These benefits have continued even as COVID-19 related travel restrictions have been lifted. Recommendations for the future include increased remote training.

        Speaker: Mr Robert Mellors (University of California, San Diego)
      • 228
        Australian Performance in International Monitoring System Radionuclide Stations – How Can Remote Stations Perform as well as Those on the Mainland?

        The Australian Radiation Protection and Nuclear Safety Agency (ARPANSA) maintains nine International Monitoring System (IMS) radionuclide stations across Australia, Antarctica, Fiji and Kiribati. A significant proportion of these are considered to be remote locations, where access is limited and local support is essential for the ongoing maintenance of the stations. This was particularly challenging throughout 2020, 2021 and 2022, where travel from Australia to many of the stations was not possible. Despite the challenges that are faced, the network under the responsibility of ARPANSA has consistently performed to an extremely high level of uptime and quality since beginning operation of stations in the year 2000. Whilst station performance data will be discussed, the focus of this presentation will be on several areas where ARPANSA has been able to optimize performance, including: core staff dedication and expertise, relationships with local operators and continuous improvement. It is intended that several real life case studies documenting the experience that has been built up over time will be presented to compare and contrast the requirements for successfully maintaining radionuclide stations to a high quality in varied environments.

        Speakers: David Hardman (Australian Radiation Protection and Nuclear Safety Authority (ARPANSA)), Marcus Grzechnik (Australian Radiation Protection and Nuclear Safety Authority (ARPANSA))
      • 229
        PTS Maintenance Radionuclide Field Activities

        One of the tasks of the Provisional Technical Secretariat (PTS), in regards to the mandate of the International Monitoring System (IMS) Division, is to support, monitor and conduct maintenance activities. In this presentation an overview of the field missions that the CTBTO maintenance radionuclide team have performed after the pandemic restrictions were lifted will be given. These activities aimed at the sustainment and reduction of downtime of the stations. These field missions included following types of activities: on-site corrective/preventive maintenance and training activities. When a problem could not be solved by the station operator or with PTS remote assistance, the PTS conducted a corrective maintenance action. Also, due to COVID-19 restrictions, some preventive maintenance activities or upgrades were postponed. These postponed activities were carried out on-site. Additionally, on-site training was delivered to station operators, increasing their knowledge on maintenance activities. In this poster presentation, we will discuss the activities of the maintenance team in the field and how this work increases the efficiency of the stations and operators, helping achieve a higher data availability.

        Speaker: Diego Ortiz Trujillo (CTBTO Preparatory Commission)
      • 230
        Feedback on SPALAX New Generation Operation

        In the context of the Comprehensive Nuclear Test Ban Treaty (CTBT), the CEA/DAM developed the Système de Prélèvement Automatique en Ligne avec l'Analyse du Xénon (SPALAX) about 20 years ago which is used in the International Monitoring System to detect xenon releases following a nuclear explosion. The New Generation of the system has been successfully developed by the CEA and CEGELEC Défense. CEGELEC commissioned several SPALAX New Generation at CEA premises. These were evaluated in France for several months before moving to operations. It is reliable and good results have been observed. New people have been trained on the system and can now operate it. CEGELEC will describe latest evolutions to the system following users lessons learned and provide feedback on the system operation.

        Speaker: Ms Axelle Gourgues (Cegelec Defense)
      • 231
        International Monitoring System Radionuclide Station State of Health Monitoring Using the Radionuclide Operations Support System

        Immediate identification of system component failures through state of health (SOH) trend analysis allows for fast resolution of International Monitoring System (IMS) station issues. The Radionuclide Operations Support System (ROSS) allows staff of the Provisional Technical Secretariat to display station SOH data, assess current station performance, and notify International Data Centre analysts of critical issues that affect IMS radionuclide station key performance indicators. This presentation will discuss examples of critical equipment failures as observed from SOH data of the various radionuclide technologies as identified using ROSS and some challenges observed in SOH data monitoring using the software.

        Speaker: Paolo Tristan Cruz (CTBTO Preparatory Commission)
    • P1.2 The Solid Earth and its Structure - 2: part 2 Zeremoniensaal & Marmorsaal

      Zeremoniensaal & Marmorsaal

      E-poster session with display of each e-poster on an assigned touchscreen

    • Workshop - Metrology 1 Prinz Eugen Saal

      Prinz Eugen Saal

      • 232
        Workshop on Metrology - part 1 Prinz Eugen Saal

        Prinz Eugen Saal

        The role of metrology in improving confidence in IMS measurements

        Description: The purpose of this workshop event is to disseminate outcomes from the Infra-AUV project relating to the value of robust calibration practices in sensor networks and the associated practical aspects for maintaining sensor systems. The project will be producing a recommended good practice guide for establishing traceability through the on-site calibration of sensor systems as one of its outputs. The contents of this guide will be featured in this Workshop.

        Speakers: Mr Richard Barham (Acoustic Sensor Networks Limited), Mr Thomas Bruns (Physikalisch-Technische Bundesanstalt)
    • Lightning talks: P2.5, P4.1, P4.2, P4.3 Wintergarten

      Wintergarten

      • 233
        Monitoring Traces of Radiocesium in Indonesian Waters and Lands as an Indicator of Nuclear Weapon Testing Activities

        The spread of radiocesium traces is strongly influenced by the circulation of wind and ocean currents around Indonesia. Seawater from the Pacific Ocean that enters into the Indonesian marine water area could distribute Cs-137 from the Fukushima release. Monitoring results show that the concentration of Cs-137 on the west coast (West Sumatera, Bangka Island, North and South Java, and Madura) ranges from 0.12 to 0.66 Bq/m3. The effects of seasonal winds can affect the quantity of trace radiocesium around Indonesia, the influence of currents from the Pacific Ocean when entering the ITF can wash away radiocesium originating from the Pacific Ocean, especially in the eastern coast area (north and south Sulawesi, Lombok Strait, Flores Sea) ranges from 0.12 to 0.39 Bq/m3. The results obtained are similar, as well as at other points, where no radioactivity of Cs-134 was found at all. According to (IAEA, 2005), the ratios of Cs-134/Cs-137 can be used to identify anthropogenic radionuclide sources in the marine environment. The ratio was 0. Therefore, the results of our study indicate that the radiocesium input was from global fallout.

        Speaker: Mr Budi Setiawan (National Research and Innovation Agency of Indonesia (BRIN))
      • 234
        Relocation of the Central Asia Comprehensive Seismic Bulletin

        The Lawrence Livermore National Laboratory, Michigan State University, and NDCs in Central Asia (Kazakhstan, Kyrgyzstan and Tajikistan) digitized seismic bulletins of analog stations between 1951 and 1992. The metadata of all seismic stations of that period were also collected. The national network bulletin data were then combined with the International Seismological Centre bulletin to form the comprehensive bulletin for Central Asia between 1951 and 2017. The bulletin consists of ~400,000 events and will serve the basis of the new probabilistic seismic hazard analysis for the region.
        We present the relocation results of the comprehensive Central Asia bulletin. We selected events with less than 355° secondary azimuthal gap, and using the MSU High Performance Computing facilities, we relocated ~250,000 events with iLoc, a single event location algorithm using regional seismic travel time predictions to improve locations. We developed a hierarchical review strategy to perform a thorough manual review with strict quality control. We show that each stage of the manual review brings incremental improvements. We also identified new Ground Truth and anthropogenic events in the region.
        The results show significant improvements in the view of seismicity, providing reliable input for the PSHA and allowing for a more accurate determination of active seismic zone boundaries.

        Speaker: Istvan Bondar (Research Centre for Astronomy and Earth Sciences (ELKH))
      • 235
        Features of Nuclear Explosion and Earthquake Waveforms from the Lop Nor Test Site Area Using Digitized Analog Seismograms of Kyrgyzstan

        The National Data Center of Kyrgyzstan and Michigan State University (MSU) are digitizing historical analog seismograms of nuclear explosions that were conducted at the People’s Republic of China (PRC) Lop Nor test site. The methodology for digitizing and data quality control was developed by the MSU team. Of significant importance is the recovery of original station calibrations and amplitude-frequency response enabling the generation of dataless files. This allows data display in units of ground motion and the ability to conduct modern digital processing on the waveforms.
        In total, 245 3-component seismograms of 26 atmospheric and underground nuclear explosions were digitized for the period 1966-1996, recorded by 35 stations at epicentral distances of 754-1542 km. For most digitized seismograms we are reliably able to recover data up to 5 Hz.
        Based on the records of seismic stations of the Kyrgyz system of seismic monitoring, a comparative analysis of the wave pattern of underground nuclear explosions carried out at the Lop Nor test site and tectonic earthquakes that occurred in the same area was carried out. The spectral ratios of the amplitudes of P- and S-waves (e.g., Sn/Pn and Lg/Pg) were measured to search for effective criteria for seismic discrimination of underground nuclear explosions and earthquakes.

        Speaker: Ms Anna Berezina (Institute of Seismology, National Academy of Sciences of the Kyrgyz Republic)
      • 236
        Waveforms from Nuclear Explosions Repository

        The “Waveforms From Nuclear Explosions (WFNE)” repository was developed and is maintained by Leidos under DTRA sponsorship. It was built as a trusted data set, starting from the previous data repository “Nuclear Explosion Database (NEDB)” that was accessed in the past by numerous users in the US and international nuclear explosion monitoring community. WFNE includes detailed information (origin, bulletin, other geophysical data) on all the 2157 atmospheric, underground and underwater nuclear explosions detonated in the world from 1945 to 2017. Over 70 000 waveforms associated to 677 of the nuclear explosions ranging from digitized analog recordings for the oldest explosions to recent IMS data are included in WFNE, and their station/instrument information, as collected from many sources. The web-based access and the presentation were updated and modernized and rendered ready for active user access. Users can search, visualize and download data of interest for their own research. Data continues to be collected from newly identified sources. Recent efforts on rescue of pre-digital seismic data via scanning and digitization provide interesting data to be added to WFNE, after completeness and quality checks. WFNE will be open for the research community’s access to source parameter data and associated waveforms from worldwide nuclear explosions.

        Speaker: Dr Victoria Oancea (Leidos)
      • 237
        Frequency of Radionuclides Reported in Remote Atmospheric Observations of Historic Nuclear Test Explosions

        The observation of atmospheric radionuclides that are associated with nuclear test explosions has a long history that started already in the 1940s. Over the decades of nuclear testing the methods were refined and mounted into the high-quality systems implemented in the International Monitoring System of the CTBTO. The project presented here is reviewing the publications about off-site monitoring of nuclear tests. In fact, many observations were done at large distances and often nuclear tests were detected at multiple locations, in general in the same hemisphere. Most publications are associated to tests that occurred in the atmosphere but observation of nuclear debris from venting of underground nuclear tests were also found. The frequency of radionuclides in remote atmospheric observations of historic nuclear test explosions is compared to several radionuclide lists considered for nuclear explosion monitoring to explore how these lists match the historic evidence. Suggestions are made how this data set is of value for validating and enhancing methods based on radionuclide analysis and related atmospheric transport simulations with the objective of identifying and characterizing the source of an event that is of relevance for atmospheric radioactivity monitoring for the Comprehensive Nuclear-Test-Ban Treaty.

        Speaker: Mr Martin B. Kalinowski (CTBTO Preparatory Commission)
      • 238
        Parametrization of Seismic Records of Nuclear Tests Conducted at the Nop Lor Test Site

        During the years of nuclear tests, a network of seismic stations of the Institute of Seismology NAS KR operated on the territory of Kyrgyzstan, the data of which are very important for seismic monitoring purposes. Most of these stations were installed far from natural and anthropogenic sources of seismic noise, on bedrock, in specially equipped bunkers and tunnels. In addition, most of the nuclear explosions from the Asia test sites, as well as peaceful nuclear explosions on the territory of the USSR, were carried out at regional distances from the stations of the network. Metadata about seismic stations were collected, including coordinates refined by modern methods, amplitude-frequency responses, etc. More than 15 000 seismograms of nuclear explosions and earthquakes were scanned with a resolution of 1200 DPI, and the records are being digitized. According to historical seismograms, a seismic bulletin was created for seismic records of nuclear explosions from the area of the Lop Nor test site, magnitudes mb, mpv, MLH and energy class K were calculated. More than 500 seismograms were processed (1966-1996), and analysis of the dynamic parameters of seismic records of nuclear explosions depending on the explosive yield and the explosion environment were carried out.

        Speaker: Ms Sezim Abyshova (Institute of Seismology, National Academy of Sciences of the Kyrgyz Republic)
      • 239
        Study of Historical Peaceful Nuclear Explosions Parameters Conducted on the Territory of the former USSR

        One of the most valuable sources for ground truth events are peaceful nuclear explosions as these were conducted in different geological environments on a vast territory. Temporary stations were deployed very often to record these events, and, in addition, in recent years work on the precise coordinates using contemporary methods was conducted. Using the records of historical analog seismograms of 1965 – 1988, a seismic bulletin of peaceful nuclear explosions conducted on the territory of the former USSR was compiled. In total, more than 1500 seismograms were processed. For this study, the archive records of the CSE IPE AS USSR network, whose stations were installed on the entire territory of the former USSR at an epicentral distance of 520-6700 km away from peaceful nuclear explosions, were used. The regional travel time curves of the main seismic phases were constructed by data of calibration sources for different regions of Kazakhstan. These were tested and compared with other regional and global travel time curves for this territory. The dependences of the regional magnitudes on the explosions yield were constructed. It was shown that the dependence is affected much by the medium in which the explosion was conducted. The obtained results can be used for the seismic stations calibration and in nuclear tests monitoring tasks.

        Speaker: Ms Irina Aristova (National Nuclear Center of the Republic of Kazakhstan)
      • 240
        Study and Application of Explosion Records for Engineering Seismology Tasks

        At the present moment, for many regions of the world, one of the topical issues is the prediction of industrial blasts seismic effects on the infrastructure and adjacent settlements. The IGR conducts this kind of work using the historical records of explosions and description of its effect on constructions as well as using the data of field experiments on mining explosions recording at the region of mineral deposits production quarries. The records of large chemical and nuclear explosions were collected; for these explosions, the typical buildings were especially constructed at the near zone, and strong-motion accelerometers were installed at different floors. In Kazakhstan, for instance, such investigations were conducted for large chemical explosions at the construction of the mudflow dam near Almaty, at the Medeo mountain area (1966, 1967), and for a peaceful nuclear explosion Lazurit (1974) at the Semipalatinsk Test Site. In recent years, using the data of the field seismic stations installed at copper and rock phosphate deposits, the effect of different yield explosions on the infrastructure of quarries and constructions in the nearest settlements was studied in quantitative oscillation parameters and in seismic intensity units. The values of seismic effect on the constructions depending on the distance and explosive mass were calculated.

        Speaker: Ms Inna Sokolova (Geophysical Survey Russian Academy of Sciences)
      • 241
        The Air Force Technical Application Center Efforts to Collect, Preserve and Integrate Historic Geophysical Data

        During the past decades, Air Force Technical Application Center geophysicists, recognizing the importance of preserving analog historic data, have led various internal efforts to rescue and preserve legacy geophysical records. We will discuss the efforts and approaches we use to collect and integrate historical nuclear explosion data into our systems and to leverage its use to support our operational and research needs.  The development and use of uniform and systematic quality control measures and metadata standards is an integral part of our prioritization processes for inclusion of event data into a curated reference database. We also developed procedures to identify ‘continuous stations’ (stations that recorded historic events and continue to operate in the present) that may provide long term empirical data. In addition, we will share some of the challenges and lessons learned in our race against time to preserve and maximize the use of this unique, invaluable and irreplaceable resource while facilitating the transfer of technical and scientific knowledge from older to younger generations.

        Speaker: Ms Lillian Soto-Cordero (Air Force Technical Applications Center (AFTAC))
      • 243
        Recovery and Digitization of Soviet Peaceful Nuclear Explosions from Russian Legacy Analog Seismograms

        The Geophysical Survey of the Russian Academy of Sciences and Michigan State University are recovering, scanning, and digitizing the historic analog seismograms of Soviet Peaceful Nuclear Explosions (PNEs). The Soviet Union detonated 122 PNEs from the mid-1960s through the late 1980s. The PNEs were conducted in a wide range of geologic settings and geographic locations, thus representing a unique data set for geophysical studies. These explosions were well recorded by the regional seismic networks, where thousands of seismograms are retained. We are generating high resolution scans of the seismograms and digitizing the waveforms for analysis. Along with the seismograms, we are recovering the original station calibrations, responses, and metadata for each station and developed code to generate Dataless SEED files for use with the digitized data. Most seismograms are from short period instruments, and when combined with the correct station calibration information, the digitization process accurately recovers ground motion signals to at least 5 Hz. The resulting digital waveforms are of high quality and are usable for quantitative research.

        Speaker: Kevin Mackey (Michigan State University (MSU))
      • 244
        Recently Digitized and Calibrated Historical Seismic Data of United States Underground Nuclear Tests Recorded on the Leo Brady Seismic Network in the 1960s and 1970s

        The Leo Brady Seismic Network (LBSN) is a small regional seismic network established in 1960 by Sandia National Laboratories to monitor US underground nuclear tests at the Nevada Test Site (now known as the Nevada National Security Site). Until the mid-1980s, data recorded by this network were telemetered as frequency modulated audio from each seismograph over telephone lines to a central location where the signals were then split — one path going to traditional seismic paper records and the other to analog magnetic tapes. While the paper records have long since been lost to history, the tapes have survived. For the past several years, we have been working to digitize these tapes and recover and calibrate waveforms from them. Herein we present the first major results of our recovery efforts, showing newly recovered seismic waveforms which, until today, have not been seen for more than half a century and have never been available in digital form. We also describe the recovery process and data quality associated with such old seismic records. These “new” old waveforms provide additional data to validate International Monitoring System models and algorithms. SNL is managed and operated by NTESS under DOE NNSA contract DE-NA0003525

        Speaker: Mr Brian Young (Sandia National Laboratories (SNL))
      • 245
        Analysis of Different Nature Events Records form the Semipalatinsk Test Site Region

        The Institute of Geophysical Research of the Republic of Kazakhstan conducts work on scanning and digitalizing of archived photo paper seismograms from the CSE IPE AS USSR. The records are digitized using WaveTrack software developed by the Novosibirsk Regional Center for Information Technologies of Russia and adjusted for data saving in contemporary formats. The main task of the project is to save the historical seismograms of nuclear explosions conducted at the Semipalatinsk Test Site recorded at regional distances and convert them into research quality waveforms. The WaveTrack digitization results were compared with records digitized previously by NXSCAN software developed by IRIS, USA. The comparison shows some advantages of the new software. The digitalized historical seismograms are used in a range of tasks related to nuclear test monitoring. The report shows the study results of dynamic parameters of digitized seismic records, energy and magnitude calculations of underground nuclear explosions (UNEs) conducted at Degelen site in the same tunnels. For UNEs, the decrease of seismic effect is observed for the second explosion conducted in geological medium partially destructed by the first explosions. Thus, a clear dependence of seismic effects as a function of the degree of destruction and fracturing of rocks is observed.

        Speaker: Pavel Ryabenko (National Nuclear Center of the Republic of Kazakhstan)
      • 246
        25 Years of Seismic, Hydroacoustic, and Infrasound Data Analysis at the CTBTO – Achievements, Changes, and Challenges

        Automatic bulletins are created using data from the International Monitoring System (IMS) seismic, hydroacoustic and infrasound stations. These bulletins are interactively analysed and reviewed by the Monitoring and Data Analysis (MDA) Section at the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO). The automatically processed Standard Event Lists (SEL3) are reviewed in detail to modify phases, parameters, and locations; raw data from all stations are also analysed and scanned to build missing events in the automatic process. This routine analysis results in delivering the Late Event Bulletins (LEB) and the Reviewed Event Bulletins (REB), which are released on a daily basis since 1999. However, over the last 25 years, the number of operational IMS stations has grown. In addition, there have been changes, updates, and improvements in the technologies, methods, and analysis tools. Here, we present statistics of the automatic processed bulletins as well as the output LEB and REB for the past 25 years. Moreover, we show how the network growth has affected the bulletins in terms of the number of detections. We also illustrate how the new tools could affect both automatically processed and reviewed bulletins. Furthermore, we discuss the routine interactive analysis challenges along with suggestions on how to overcome these.

        Speaker: Mr Ehsan Qorbani Chegeni (CTBTO Preparatory Commission)
      • 247
        Possible Historical Seismic Recordings of the 6 July 1962, Sedan Nuclear Explosion by the Mechanical Seismographic Stations of the National Seismological Service of Mexico

        During the first half of the 20th century, most earthquake ground motions in Mexico were recorded by the Mexican seismological network, equipped with different Wiechert mechanical seismographs on smoked paper. Nowadays, the analogue seismographic collection of Mexico is stored and maintained at the Joint Library of Earth Sciences of UNAM, as part of the Sismoteca-SSN project, to preserve, digitize and reuse these legacy data. Due to the availability this collection, we have found different smoked paper seismograms at the Tacubaya (TAC) Central station for the period from 5 to 7 July 1962. On 6 July 1962, a shallow underground nuclear test was conducted in the Yucca Flat, Nevada. This event, known as the Storax Sedan nuclear test had a yield equivalent of about 104 kilotons TNT. After visual inspection of the seismograms from the astatic horizontal Wiechert seismograph (17 000 kg) in TAC station, at a distance of 2560 km away from the nuclear test site, different possible seismic traces could be related with that nuclear event. In this work we analyse the seismic traces recorded in these smoked seismograms, in order to define if this explosion could have been recorded at this distance by a high sensitive mechanical seismograph in Mexico.

        Speaker: Mr Miguel Angel Santoyo (Universidad Nacional Autónoma de México (UNAM))
      • 248
        Evaluation of the Event Detection Level of the Cuban Seismic Network

        The detection level of a seismic network is the ability to estimate the level of detection and have a tremendous importance both in the design of a new network and in determining whether a given network can recognize seismicity consistently, or needs to be improved in some way. We determine the detection level of the Cuban seismic network using the empirically estimated seismic noise spectral level at each station site and some theoretical relationships. The minimum local detectable magnitude thus depends on some network parameters such as the signal to noise ratio and the number of stations used in the calculation. We also demonstrate the effectiveness of our predictions by comparing the estimated detection level with those empirically determined from one year of data of the Cuban seismic catalog. Our analysis shows, on the one hand, which areas the current Cuban network should be improved, also depending on the regional pattern of faults, and, on the other hand, indicates the magnitude threshold that can be assumed homogeneously for the catalog of Cuban earthquakes in 2020.

        Speaker: Eduardo Rafael Diez Zaldivar (Cuban National Centre for Seismological Research (CENAIS))
      • 249
        Alert System to Detect International Monitoring System Station Outage at the National Data Centre Madagascar

        In the framework of application of Comprehensive Nuclear Test Ban Treaty, 371 facilities run across the world to form the International Monitoring System. Madagascar hosts two of these stations, I33MG an infrasound station and AS61, an auxiliary seismic station. These two stations need to operate continuously to detect any nuclear test. To minimize downtime during an eventual outage, the National Data Centre Madagascar via its local operator team developed an alert system using Raspberry Pi and a GSM module. In case of an outage of up to 30 minutes, the system sends an SMS via local operator to the team showing the last received frame and the team start to solve the issue.

        Speaker: Mr Mamiharijao Rambolamanana (Institute and Observatory of Geophysics of Antananarivo (IOGA))
      • 250
        Integration of SeisComP Quality Control Data and Datalogger State of Health information in Zabbix

        The Geophysical Institute in Ecuador uses SeisComP for acquisition of waveforms of around 150 seismometer and accelerometer stations. SeisComP has several modules (SCQC, SCQCV, etc.) that allow the operator to check the quality of the waveforms acquired, nevertheless the module's interfaces could be difficult to use and not very interactive. For easy access to the information of waveform quality control (QC), we developed SCZABBIX, an open source Python module, that sends the QC information created by SCQC to a Zabbix server so we can leverage on the whole set of tools provided by the open source software Zabbix, like interactive graphs, thresholds, triggers, alerts, etc. This allowed operators to detect problems in transmission, estimate parameters like data availability, ping response time, latency, etc. in a quick and flexible way for historical or real time data. Additionally, we developed SOH_ZABBIX, which are some Python modules that capture state of health information from dataloggers like Quanterra, Reftek, etc. and send it to Zabbix so we can test its new triggers for automatic anomaly detection and determine if they could be used to anticipate problems related to battery, temperature, use of disk, etc.

        Speaker: Mr Wilson Acero (Instituto Geofísico de la Escuela Politécnica Nacional (IGEPN))
      • 251
        International Monitoring System Station Performance Over Time Using Reported Parametric Data from the International Seismological Centre Bulletin

        Many of the primary and auxiliary seismic stations of the International Monitoring System (IMS) have been in operation for more than 20 years. Tracking changes in station performance for this duration can prove challenging, requiring continuously reported data across the time period. Using phase picks reported to the International Seismological Centre (ISC) it is possible to evaluate historical changes in individual stations performance. Metrics which are used to track changes at the stations include; average monthly travel time residuals, evaluation of travel time residuals by distance and hypocentre location and comparison of reported polarities with available earthquake mechanism solutions. These metrics can indicate when a station polarity was inverted or highlight an improvement in travel time residuals occurring over a short time period. We will show how best to access this information using the CTBTO link to the ISC database and highlight historical examples of changing station performance. Additionally, where station response files are publicly available for IMS stations we will demonstrate independent response file checks currently being developed by the ISC.

        Speaker: Dr Ryan Gallacher (International Seismological Centre (ISC))
      • 252
        Evaluation of Accelerograph Data Quality System Based on Machine Learning on Seismic Networks in Indonesia

        An analysis of the quality of accelerograph data has been carried out from 669 station locations. This aims to monitor and evaluate the data quality of accelerograph equipment at the Meteorology, Climatology, and Geophysics Agency (BMKG). Advances in machine learning can mean the ability to diagnose or even predict equipment problems so that site visits can be scheduled more cost-efficiently. The analysis was carried out by machine learning using accelerograph data in Indonesia. The study compares two machine learning models: accelerograph data analysis using Multilayer perceptron (MLP) and k-nearest neighbor (KNN). The output of machine learning models consists of two types of classification, namely four class output data quality in general, namely good condition, fair condition, bad, and off condition, at the output seven class output represents problems with the tool, such as high noise above the accelerometer noise model, sensor damage, etc. The analysis of the two models shows that MLP has a balanced accuracy of 85.5%, and KNN has a higher balanced accuracy of 91.2%. So in this study, a machine learning model was obtained to identify problems with the accelerograph equipment and evaluate network data quality for observing strong earthquakes due to seismic waves at BMKG.

        Speaker: Mr Kurniati Retno Dewi (Indonesian Agency for Meteorological, Climatological and Geophysics (BMKG))
      • 253
        Progress on the International Data Centre Seismic, Hydroacoustic and Infrasound Reengineering Project and Station State of Health

        The International Data Centre seismic, hydroacoustic and infrasound (SHI) reengineering project began in 2014 with the goal of creating modernized, open-source software for SHI processing, and improving maintainability and extensibility to the system. Since 2019, the project is under active development, and the current main area of work is the elaboration of a modernized station state of health (SOH) system. This system monitors in real time the performance and status of the International Monitoring System. The future system is based on the Geophysical Monitoring System being developed for the US National Data Centre and shared as a voluntary contribution. It is being extended to address Provisional Technical Secretariat-specific monitoring requirements. This poster introduces the general architecture and highlights recent progress on the implementation of the new SOH monitoring features.

        Speaker: Thibault Arnal (CTBTO Preparatory Commission)
      • 254
        Evaluation of the International Monitoring System Seismic, Hydroacoustic and Infrasound Network Performance with NetMOD

        Simulating and analysing the detection capabilities of the seismic, hydroacoustic and infrasound networks of the International Monitoring System (IMS) can contribute to the enhancement of the Treaty’s verification regime and its capabilities. Simulations carried out with the Java-based tool Network Monitoring for Optimal Detection (NetMOD) allow one to evaluate the overall network performance of the IMS and assist the International Data Centre (IDC) in continuously monitoring, assessing, and reporting on the operational status. This quantifies the variations in detection capability over time and studies the impact of several parameters on the network coverage (e.g. seasonal variation, weather conditions, station noise levels, outage of key stations, period of large events). From one side, the results can help to evaluate the resilience of the network in homogeneously monitoring the globe and assist in analysing events of interest. On the other side, the results can provide input to the IMS maintenance and recapitalization by assessing the importance of a station installation or station failure on the overall performance of the network. NetMOD is developed by Sandia National Laboratories and is provided to the Provisional Technical Secretariat as a voluntary contribution in kind of the United States.

        Speaker: Ms Ichrak Ketata (CTBTO Preparatory Commission)
      • 255
        CLFMiner: An Artificial Intelligence, Temporal Data Mining and Modelling Approach for Monitoring, Exploring and Analysing Continuous Data, Timeliness, Data Availability and Distribution Process

        The International Data Centre (IDC) receives from stations more than ten gigabytes of raw data on a daily basis. Most of those data are collected and transmitted as continuous data digitally signed frames. In normal operations the frames are received in chronological order of their acquisition/detection time. However, some frames may be missed, corrupted, partially delivered or sent several times. It is vital to Treaty verification to receive the data in a timely manner and that it is complete. In this paper we propose an artificial intelligence, temporal data mining and modelling approach for monitoring, exploring and analysing continuous data. The proposed temporal continuous data model is designed using a well defined knowledge based system and inference engine. Also, with the proposed approach by mining the temporal data contained in the concise list of frames, we can easily calculate, in an hourly basis or less, the timeliness, data availability and completeness of the received data. In addition, it will enable us to discover hidden patterns, evaluate receiving and forwarding processes, asses the station operation as well as generating distribution performance indicator metrics. The generated results and metrics can be fed to big data tools (e.g. Elasticsearch) as well as using open source dashboards for data presentation.

        Speaker: Mr Shaban Laban (CTBTO Preparatory Commission)
      • 256
        Enhance Data Quality Control with Interactive Station Monitoring Tools in the OPS Center

        The International Monitoring System (IMS) is a globally distributed network of monitoring facilities using sensors from seismic, hydroacoustic, infrasound, and radionuclide technologies. The need for data availability increased the significance of data quality monitoring. This task is addressed through the creation of a platform for the fast and easy identification of data acquisition problems, as well as regular activities to ensure that station characteristics meet the requirements of the IMS draft Operational Manuals. The Provisional Technical Secretariat (PTS) has developed a Multi-Technology Integration Portal ( MuTIP) internal platform with a variety of monitoring tools to facilitate data quality monitoring. MuTIP facilitates PTS user access to information allowing technical review of data quality and analysis through the aggregation and representation of technical results from a variety of internal PTS data sets and databases. MuTIP provides information such as station summary (PSD/PDF, Residual, and Calibration). MuTIP has also interfaced with Grafana (SOH), PRTools, JIRA instances (IRS, ITS, SHD), CAMT, DOTS, and International Data Centre databases. MuTIP provides good support for data quality monitoring in terms of troubleshooting (reliability, efficiency, accuracy, and timeliness) to maintain good station/IMS network performance in daily OPS data monitoring. Ensuring that the station is operating properly, especially in meeting data (availability, surety, and quality) requirements.

        Team work with IDC OPS colleagues.

        Speaker: Ms Rizkita Parithusta Assef (CTBTO Preparatory Commission)
      • 257
        Scheduled Calibration of International Monitoring System Seismic, Hydroacoustic and Infrasound Stations

        Scheduled calibration activities at International Monitoring System (IMS) seismic, hydroacoustic T phase and infrasound stations are part of the quality control requirements defined in the draft IMS seismic, hydroacoustic and infrasound Operational Manuals. Depending on the technology used, the approach for scheduled calibration can be different in some aspects. However, the overall objective remains the same: controlling the quality of IMS measurement systems by comparing their measured sensitivity and response against their nominal values defined at the time of station certification or revalidation. Results from calibration activities are reported by the CTBTO to States Signatories on a yearly basis. This presentation shows processes in place to implement calibration activities, current and historical calibration results, and associated progress and challenges.

        Speaker: Yacine Sid Ahmed (CTBTO Preparatory Commission)
      • 258
        Downtime Statistics and Failure Analysis of International Monitoring System Seismic, Hydroacoustic and Infrasound Stations

        The International Monitoring System (IMS) is one of the four elements of the Provisional Technical Secretariat (PTS) verification regime. The seismoacoustic component of the IMS network is comprised of seismic, infrasound and hydroacoustic stations participating in the underground, air, and underwater explosion monitoring. The minimum requirement in terms of data availability for each station is 98%. This means that each station should be able to send data to the International Data Center over 98% of the time, regardless of the challenging environment in which they are located. When an issue occurs at a station, it is discussed through the IMS Report System (IRS). Failure analysis based on information in the IRS has been performed since Nov. 2011 with the objective of triggering the required engineering activities, initiating further analysis when needed (root cause analysis), using trends to anticipate future failures, and verifying that the implemented engineering solutions led to improvements in reliability. This poster presents historical results on data availability metrics, categorization of failures leading to station downtime, and engineering projects aiming to enhance station robustness to downtime.

        Speaker: Yacine Sid Ahmed (CTBTO Preparatory Commission)
      • 259
        Revalidation Process for International Monitoring System Waveform Technologies Stations

        Revalidation of International Monitoring System (IMS)stations is a rest assured approach to demonstrate compliance with IMS minimum requirements for stations that underwent major upgrades or equipment changes that have caused station response modification. The Configuration Management Board (CMB) decides on the
        need for the station revalidation after the case submission to CMB by IMS Engineering and Development Section of the CTBTO. Upon completion of the modernization works at the station the revalidation report is submitted by IMS/ED for review of the Certification Group. The report content is standardized demonstrating the updated technical specification Table and description of the testing process. The report is lean on the compliance demonstration in the following areas: noise study analysis using a newly developed calculator for different equipment settings; station calibration; testing of the status bit settings; compliance with cd1.1 requirements for data transmission and data surety aspects; station documentation update and DOTS population. This presentation demonstrates examples from revalidation reports with a demonstration of the key compliance with IMS requirements of ever changing technical solutions applied to the station upgrades in recent years.

        Speakers: Ms Adriana Molero Alonso (AddProject), Mr Yury Starovoyt (AddProject)
      • 260
        Next Generations of the Global Communications Infrastructure: The Role of Low Earth Orbit Satellites

        Broadband access and low latency are available globally thanks to the increasing availability of low earth orbit satellites. There are a variety of geographical locations where the International Monitoring System stations are installed that could benefit from this type of service. Maximizing data availability and simplifying complex infrastructure -normally associated with the deployment of VSATs- and providing innovative services and applications through broadband availability would enhance not only transmission of data but also the customer experience available to a station operator in remote regions. Currently, GCI III is moving through its mid life cycle and technology refreshment; the GCI IV planning will begin in the mid term, with initial deployments within five years.
        Currently there are three constellations of satellites in different degrees of deployment with some other providers in the planning stage. This paper presents the technology and explores its potential application in selected remote locations to provide an overview of potential improvements in the transmission of data. It also provides the possibility of novel applications for station operators that are typically subject to bandwidth limitations and latency issues.

        Speaker: Mr Fernando Araujo (Institute of Electrical and Electronic Engineers (IEEE))
      • 261
        A New Method of Seismometer Orientation Correction via Amplitude and Energy Based Teleseismic Receiver Function Measurements: Test Case on West Africa and Adjacent Islands Stations

        Accurate seismic station orientation is important for seismic waveform or particle motion based studies. Station misorientation has been studied using P wave particle motion and Rayleigh wave arrival angle, which may be affected by the complexity of earthquake sources. Recently, P wave receiver function (PRF) using tangential component has been proposed for misorientation estimation. In this study, two new methods using amplitude and energy based objective functions of both radial and tangential components of PRF to estimate station misorientations, are introduced. The two methods are tested using 21 stations in West Africa and adjacent islands, taking into consideration the effect of the different geologic terrains i.e. islands, coastlines, and inland areas. The difference between the two methods are investigated, considering the effects of Gaussian factors, back-azimuthal coverage, number of events, and structural heterogeneities. Both methods produce similar results, which are consistent with a previous study. However, comparison between radial and tangential components indicates that results based on radial components are more stable than tangential components which may be more sensitive to heterogeneities and background noise. Our study suggests that both methods produce more consistent results for inland stations compared to islands/coastal stations, and objective functions for radial components are more stable.

        Speaker: Mr Abayomi Osotuyi (University of Science and Technology of China, Hefei, China)
      • 262
        High Performance Broadband Seismic Station Installations in the Caucasus and Central Asia

        The Seismic Network Expansion in the Caucasus and Central Asia (SNECCA) project began in 2019 to upgrade national seismic network capabilities in Armenia, Azerbaijan, Georgia, Kazakhstan, Kyrgyzstan, and Tajikistan. The United States participated in this collaboration with support from the U.S. Department of Energy and Lawrence Livermore National Laboratory. All six countries utilized a common design concept for broadband station installations. The design consisted of steel- or plastic-cased postholes (shallow boreholes) with above grade electronics to achieve a robust, secure station with a well installed sensor. The station design was based on the successful deployment and operation of several hundred stations in Alaska and western Canada as part of the U.S. National Science Foundation’s Transportable Array project. Station construction was adapted to the drilling capabilities and infrastructure available in each country. The design objective was to create low noise, robust, uniform stations that will operate reliably and securely, using a repeatable and consistent station construction and installation process. In this presentation we will cover the design concept, realizations of this concept achieved in each country, and preliminary data. The SNECCA project is implemented through the Seismic Targeted Initiative of the International Science and Technology Center and the Science and Technology Center in Ukraine.

        Speaker: Robert Woodward (Incorporated Research Institutions for Seismology (IRIS))
      • 263
        Portable Flexible Solar Charging Pack for On-Site Inspection

        For most of the inspection area, there would be no electricity supply. The inspection team should be self-sufficient especially for the perspective of electricity supply, since that most of the mission critical or health and safety equipment would rely almost solely on electric power. This work proposes a portable flexible solar charging pack for on-site inspection activities. Flexible solar cell is a new type of energy material which is flexible in physical nature and its power capacity could be enough to provide emergent charging supply to the inspectors’ portable equipment during field operations. Via cascade connection, several solar charging units could jointly provide more power supply to other power-consuming equipment. The folding size of one solar charging unit is 29cm16.5cm, with the expansion size of 120cm29cm. Its power and weight are 37w and 0.48kg respectively. As a result, a single solar charging pack consisting of three solar charging units would have more than 100w of power capacity, with USB or other customized output connectors. The portable flexible solar charging pack has been tested under hot, humid and extremely cold environments and has other characteristics of waterproof and high reliability. The working team is looking forward to the practical test trial at the upcoming 2025 Integrated Field Exercise.

        Speaker: Ms Jing Yang (HOPE Investment Development Co. Ltd.)
      • 264
        Backup Cellular Communication System for Infrasound Monitoring Stations

        In close and constant collaboration with the CTBTO, Enviroearth has developed a backup intra-site communication solution working through a cellular network. This backup system was fully designed according to CTBTO specification. Its low power consumption, communication protocol and easy implementation on-site make it well adapted to the infrastructure of infrasound stations and its integration to current main communication system (radio, fiber optic, copper wire/ethernet, VSAT). This cellular solution will allow a permanent redundancy and ensure a continuous communication between CRF and remote elements in case of the main communication system failure/outage, thanks to its automatic failover mode. The cellular backup system will run within pre-established cellular network (e.g. 2G, 3G and 4G) and through a sever infrastructure with VPN tunnel management.

        Speaker: Maxime Grillandini (Enviroearth)
      • 265
        Power Generation and Distribution Systems at the Base of Operations for On-Site Inspection

        One challenge of on-site inspection (OSI) is preparing for deployment to unknown locations with unknown resources. A critical element of a functional base of operations (BOO) is stable and reliable electricity. The current component for the power system for OSI include diesel generators, UPS and hybrid power system that can accept power from other generation sources, such as solar. UPS systems allow for quiet time without the diesel generators reducing fuel usage and CO2 production. The system is designed to be resilient and has management software to switch power sources depending on the power consumption at any point in time. The BOO systems are also supplemented by field deployable power banks and solar panels for powering technical equipment such as the SAMS mini arrays and noble gas samplers.

        Speaker: Samuel Toon (CTBTO Preparatory Commission)
      • 266
        Management of an International Monitoring System Station in Brazil.

        Brazil participates in the CTBTO in several ways, as it has an institution, the National Center for Monitoring and Alerts of Natural Disasters (CEMADEN), which became responsible for the implementation of the Brazilian National Data Center (NDC). The country also has a radionuclide laboratory, RL4, which is in the certification process. In addition to operating an infrasound station, IS9, and a primary seismic station, both in the city of Brasília, we have two seismic auxiliaries , AS10 and AS11. We also have a radionuclide station in planning, RN12, and another in operation and certified, RN11. RN11 is operated by the Institute of Radioprotection and Dosimetry and the experience gained over the years is presented, emphasizing good practices, maintenance, training and lessons learned, facing the health crisis (COVID-19), management, obtaining and using equipment and spares. And the legal limitations and human resources will also be presented to share the experience acquired in the management of RN11.

        Speaker: Mr Rocio Reis (Institute of Radiation Protection and Dosimetry (IRD))
      • 267
        Enhance Battery Management to Reduce Power Issues at Indonesia Seismic Stations

        All CTBTO stations in Indonesia are powered by solar panel although some are helped by commercial power lines. All those systems require a battery bank. Since 2008 until 2021 there was 10 cases caused by battery problem which held up data transmission from six CTBTO stations in Indonesia to the National Data Centre and the International Data Centre. In this presentation we will discuss how to choose the right batteries, how to manage them, when it is time to replace them and how to maintain them to support sustainable station operation and reduce power problems

        Speaker: Mr Destiawan Kriswibowo (PT. Mindotama Avia Teknik)
      • 268
        The use of LIFePO4 Batteries as a Back Up Power Source for Extreme Environments and Considerations of the Power Supply Design for Such Locations

        The emerging technologies of Li-Ion batteries offer new design possibilities for remote monitoring station power supplies. Based on recent installations and testing of these batteries and complementary equipment, the Engineering and Development Section of the
        International Monitoring System Division presents the results of both field and desktop studies, describing the advantages and disadvantages of using LiFePO4 batteries, as well as general design considerations for use of such technologies within the International Monitoring System network.

        Speaker: Mr Gregory Brenn (CTBTO Preparatory Commission)
      • 269
        NORSAR AS72/SPITS Power System Upgrade

        NORSAR is the Norwegian National Data Centre (NDC) and operates six stations of the International Monitoring System. These are the primary seismic arrays NOA/PS27, ARCES/PS28, the auxiliary seismic array SPITS/AS72, the auxiliary single seismic station JMIC/AS73, the infrasound array IS37 and the radionuclide station RN49. It is crucial to have a stable power supply with a sufficient battery bank capacity to the stations and the auxiliary station AS72/SPITS was refurbished to secure stable operation for the future. This presentation will give an overview of NORSARs choice of system and the work with replacing the previous power supply system. The old system consisted of a lead acid battery bank, two stirling generators, solar panels and a wind turbine. The new system is a complete UPS system from Eltek (a Delta group company) with lithium-ion batteries, new solar panels and Cummins diesel generator in addition to the wind turbine.

        Speaker: Mr Jon Magnus Christensen (Norwegian Seismic Array (NORSAR))
      • 270
        International Monitoring System Seismic Station Power System Design

        The correct operation of a seismic station depends on many factors. A crucial one is the provision of power required for station to operate at the established standards. Given that the Paso Flores, PLCA/PS01, seismic station power system currently in use is at the end of its life cycle, that it was not designed for the current demands and, evaluating all the technologically available alternatives for replacement, it is presented a design based on the use of solar panels as main source, a bank of batteries to store energy and a thermoelectric generator without moving parts, as a supplementary energy source to work during the winter months when solar radiation is low.

        Speaker: Juan Pablo Aguiar (INPRES)
      • 271
        Sensor Monitoring And Reliable Telecommunications Cables: Integration of Environmental Sensors Into Submarine Telecommunications Cables for Improved Ocean Monitoring

        Innovative deep ocean monitoring technologies are crucial to catalyzing fundamental improvements in mitigating natural disasters, reducing human vulnerabilities, and determining environmental threats. An attractive but untapped resource is the global submarine fibre optic cable network, which carries over 95% of international internet traffic. Key components of undersea fibre optic cable systems are repeaters, which are placed every 60-100 km along the cable to provide optical signal amplification, and provide a unique opportunity to deploy sensors globally. Installing Sensor Monitoring And Reliable Telecommunications Cables (SMART) repeater based sensor systems that include seismic, pressure, and temperature sensors will revolutionize our ability to monitor earthquakes, nuclear tests, tsunami, global climate change, and the security of major telecommunications infrastructure. While the SMART concept has been discussed and evaluated for over 10 years, developing a SMART repeater requires substantial research and development investment to validate the technology. Subsea Data Systems has developed a fully operational prototype SMART repeater sensor system. Our system includes best in class sensors validated by the scientific and monitoring communities, coupled with the data formatting and transmission frameworks already accepted by these communities and in extensive use worldwide. Here we present our ongoing efforts to make fully validated SMART cable systems a reality.

        Speaker: Matthew Fouch (Subsea Data Systems)
      • 272
        New Security Scheme for Data over Wireless Network Connectivity with the International Monitoring System

        The security system designed for the Internet of Things (IOT) should be able to detect and prevent both internal and external attacks. This work proposes a lightweight and low energy encryption algorithm to secure data over wireless networks. The proposed algorithm meets the requirements of data and is suitable for wireless devices and sensors. It is capable of reducing the execution time and power consumption of the encryption process compared with the state of the art standard algorithm and at the same time maintains the desired security (confidentiality) level. A comparison between the proposed algorithm, the advanced encryption standard (AES) and other lightweight algorithms proposed by other research works is conducted and the results are promising. Using the proposed algorithm, a significant amount of time and energy consumption reduction is achieved to reach approximately 35% improvement over the standard AES algorithm accompanied with good level of complexity in the encryption process, making it more suitable for the wireless environment. The aim of this study is to reduce the power consumption of implementing encryption algorithms on the sensors using in the International Monitoring System. Accordingly, increasing work capacity of the sensor's battery.

        Speaker: Mohammed Ghanim Jadaan Al-Gburi (Iraqi National Monitoring Authority (INMA))
      • 273
        Cost Effective Space Based Internet of Things Constellation Enabling Information Technology Solutions

        "TianQi" LEO micro-satellite Internet of Things (IoT) constellation, is a commercially running space based IoT system, which is composed of 38 LEO micro-satellites, and will be fully deployed by the end of 2023. Ground terminals are portable and cost effective, with power consumption as low as 100mw. The constellation could provide global users such as CTBTO with "air, ground and sea integration" satellite IoT data communication service. Each micro-satellite weight is about 20-50 kg with a power consumption of 50-100W. The micro-satellites would be launched into circular orbit of 500-900 km altitude, which would bring advantages such as short transmission delay, low path loss and low power consumption, low cost and miniaturization of user terminals. "TianQi" LEO micro-satellite IoT constellation would establish a global coverage 0.2kbps to 6kbps narrow bandwidth communication network, capable enough to provide varieties of solutions to CTBT application scenarios, such as operation and maintenance of remote International Monitoring System facilities, emergency communication and health and safety of on-site inspection team and inspectors, real time tracking and CoC solution to on-site inspection samples, etc.

        Speaker: Mr Peng Li (China Arms Control and Disarmament Association)
      • 274
        GCI support for a Virtual National Data Centre

        In a constant evolving digital world, there is a need for flexible way to secure the CTBTO data and products sent over the Internet. High levels of flexibility can be achieved by implementing programable, intelligent, VPN systems that can be deployed without the need for dedicated physical hardware. This system of secure communications can be deployed in as a software implementation, eliminating the need for physical network infrastructure, either on premises or in a platform as a service environment. There is only one requirement: Internet access. VPN HUBs offer a highly flexible design model:
        hardware or software or a mix of both - the entire VPN system can be recovered in a short time with a high level of automation. A VPN system requires minimal human interaction to deploy, thus reducing the probability for errors. The entire system can be backed up daily on a USB stick and redeployed fast on case of emergency. In essence, a solution to securely send data and products to National Data Centres without the need for physical networking equipment.

        Speaker: Mr Marius Popa (CTBTO Preparatory Commission)
      • 275
        Commercially Available Data Security Protection Solution to International Monitoring System and On-Site Inspection

        As a solemn legal proof of either Treaty compliance or violation, data security of the Comprehensive Nuclear-Test-Ban Treaty (CTBT) verification infrastructure plays a vital role for the authority of CTBT regime. For most important cases within the CTBT verification infrastructure, such as the International Monitoring System (IMS), data gathered at internationally distributed IMS stations and transmitted through GCI to the International Data Centre (IDC) in Vienna, on-site inspection (OSI) voice communication and data transmission among inspectors, base of operations (BOO) and the CTBTO, there is a need to make a standing arrangement to prevent data from being eavesdropped on or intercepted. This work would carry out a full-range solution to IMS and OSI with secured data transmission under various network communication scenarios. Link encryptor provides protection for digital data transmission on trunk lines such as microwave, satellite and troposcatter through the encryption of all data including the protocol itself. IP encryptor is designed to protect IP communications over TCP/IP network by adopting encryption, identity authentication and data integrity verification. Radio encryptor is designed to work with HF/VHF/UHF radios for secured voice and data communication.

        Speaker: Mr Yong Sun (Space Star Technology Co. Ltd.)
      • 276
        Data Model and Data Access Architecture in the Geophysical Monitoring System

        Sandia National Laboratories is developing the Geophysical Monitoring System (GMS) to modernize the United States National Data Center (USNDC) waveform processing system. The United States is providing the common architecture and processing components of GMS as a contribution in kind to accelerate progress on International Data Centre (IDC) re-engineering. A key aspect of GMS architecture is the Common Object Interface (COI) specification, which includes a data model and an access application programming interface (API). The data model is a collection of data structure definitions describing all the data stored by GMS and the access API specifies the available query and storage operations. The COI specification is independent of any storage solution. This decoupling facilitates changes to the storage solution with minimal impact to the GMS application software; likewise, the data model and GMS applications can be updated with minimal changes to the storage solution or schemas. One GMS COI implementation, the data bridge, provides clients access to legacy system data through web services. This poster describes GMS COI and data bridge architecture.

        Speaker: Mr Benjamin Hamlet (Sandia National Laboratories (SNL))
      • 277
        Performance Enhancement of Flexpart Atmospheric Transport Model for GPU Environment

        The Flexpart Atmospheric Transport Model is used in daily operations at CTBTO for the  backtracking of radionuclides based on measurements at 80 sites worldwide. Over 280 simulations are performed each day and it is desirable to make each simulation run in a shorter period of time. With increased availability of GPU environments, it is natural to consider their potential in speeding up the Flexpart simulations. Work is currently underway to transform a CTBTO customized Flexpart v10 into a code that can efficiently use GPUs. To date much effort has been expended in getting this code (and its dependencies) to compile and execute in an NVIDIA Fortran (nvfortran) environment, leading to discovery of bugs in the nvfortran compiler, resolved by NVIDIA as a result of our reports. While awaiting resolution from NVIDIA, we have performed detailed profiling on smaller problem sizes in order to identify the “hot spots” of the code where GPU optimization might provide the greatest benefits. Work is now underway to isolate the “hot spot” regions of code into test modules suitable for extensive iterative experimentation, development and testing. This work is ongoing, and this presentation will describe a detailed overview of the project and its current status.

        Speaker: Mr Donald Morton (Boreal Scientific Computing)
      • 278
        Design of Human Activity Recognizer as Android Smartphone Digital Filter for Earthquake Signal Processing

        Smartphone accelerometers can be used to record earthquake signals to support disaster mitigation in Indonesia. Human activities produce significant noise to accelerometer data on smartphones. Human activity recognizer (HAR) functions to sort out human activity signals from earthquake signals recorded by smartphone accelerometers. This study aims to reduce the linear acceleration signal of human activity on the Android smartphone accelerometer. The HAR application as a smartphone accelerometer digital filter includes several design stages, namely data collection, feature extraction, activity data classification and determining the Butterwoth type filter design based on activity data. These activities include sitting, standing, lying down, walking and running. The Butterworth type digital filter is designed based on the dominant frequency of the human activity acceleration signal. This filter is installed in the server program and then tested against activity signals carried out in the Central BMKG earthquake simulator. The test results show an increase in the percentage of earthquake signals from 3.87% to 64.61% and a decrease in the percentage of human activity signals from 96.13% to 35.39%.

        Speaker: Mr Haryas Wicaksana (Indonesia Agency for Meteorological Climatological and Geophysical (BMKG))
      • 279
        WFaaS: A New Modern, Embedded, Web Based, Configurable and Portable Monitoring Service for Monitoring International Data Centre Different Processes

        The International Data Centre (IDC) is using critical and complex systems with several distributed processes for receiving, processing, disseminating and archiving data and products. A dedicated tool called WorkFlow is used, among other tools, to monitor those systems. The tool is only available in Linux machines, uses intensive database resources, is hard to maintain and requires expertise for configuration. We are prototyping a new modern, embedded, web based, configurable, user friendly and portable monitoring service to help the IDC staff and its operations centre for effectively and efficiently monitoring the different systems. The states of the different processes are collected and cached independent of the IDC databases and can be shared among clients without exhausting the IDC databases. The front end is based on latest Hypertext Markup Language (HTML5) specifications and JavaScript. While the back end is implemented by Python and uses Tornado web framework. Also, several different views, flow types, roles, and permissions can be implemented. Additionally, the service is capable of and can be configured to monitor the states of any temporal data. The different capabilities of the service will be presented. Also, the advantages and limitations of the new service are outlined. Finally, future directions and recommendations will be discussed.

        Speaker: Dr Shaban Laban (CTBTO Preparatory Commission)
      • 280
        The Meteorology, Climatology and Geophysics Agency VSAT Network Disaster Recovery Plan as Efforts to Optimize Data and Sending Information for Meteorology, Climatology and Geophysics

        The Meteorology, Climatology and Geophysics Agency (BMKG) is a government agency that has the task of providing data and information services for meteorology, climatology and geophysics as well as delivering information to the public and related agencies. BMKG empowers and relies on the VSAT network which works 24/7. The BMKG VSAT communication network is a system that connects all systems within the integrated BMKG environment and requires a real time data exchange process. The public is increasingly critical in demanding that BMKG information be obtained more quickly, precisely, accurately, easily understood, and can reach all corners of the country. The paralysis of the VSAT network in the BMKG environment is critical because it can cause communication paralysis both internally and externally at BMKG. Therefore, the development of the BMKG must be carried out in an integrated manner accompanied by backup (disaster recovery) so that the dissemination of weather information and disaster events for the community is not disrupted. Data collection was carried out by conducting literature studies, conducting interviews with users and administrators of BMKG assets, observing BMKG assets, and studying organizational documents. The results of this study are DRP documents that are adjusted to the BMKG duties and functions.

        Speaker: Mr Reza Aria Nugraha (Meteorology, Climatology, and Geophysical Agency of Indonesia (BMKG))
      • 281
        An Intelligent Alerting Approach Based on WiFi Channel State Information Sensing for Earthquake Precocious Signs

        Traditional sensing techniques are recognized to be labor and technically intensive for practical adoption. As a result, researchers are employing alternate sensing techniques. One of the major technologies for sensing environment is variations in WiFi channel state information (CSI) that describes the channel state between the transmitter and the receiver. With its sensitivity to environmental dynamics, due to it ubiquity WiFi signal is now widely used for a variety of sensing applications in indoor environments, such as gesture recognition and fall detection, in addition to its primary usage for communication. WiFi based sensing offers non-contact sensing in a private mode, simultaneous sensing and data transmission without additional connection infrastructure, and remote sensing without handheld sensors. In this paper, we propose a new approach based on data collected from WiFi-CSI analysed in pretrained machine learning model to detect precocious signs of earthquake, caused by the first energy emitted by an earthquake, the P waves, which rarely cause damage but cause some environment changes like some ceiling lights move and some static objects shake slightly, movements that affect electromagnetic waves and can be sensed with wireless signals through CSI .

        Speaker: Prof. Mohamed Serrhini (University Mohamed Premier Oujda)
      • 282
        NDC-in-the-Cloud: Flexible and Reliable Cloud Resources for National Data Centres

        Capacity building efforts for National Data Centers (NDCs) commonly involve the provisioning and shipment of physical hardware systems and the training, installation, maintenance, and distribution of the NDC-in-a-Box (NIAB) software suite. “NDC-in-the-Cloud” (NIAC) is a set of cloud-hosted resources for National Data Centers that uses cloud services to streamline these efforts, while also offering new flexibility and reliability to users. It provides NDCs with cloud based versions of the familiar NDC-in-a-Box software and data, as well as a blueprint to create secure cloud based resources to use these data and software in their own cloud accounts. With this approach, we seek to increase access and processing capability for NDCs, and decrease any logistical burden associated with shipping physical hardware. The NIAC prototype employs Amazon Machine Images for software distribution, elastic compute cloud virtual hardware in the Amazon Web Services commercial cloud for computing, virtualized desktops accessible via web browser, and an “Infrastructure-as-Code” approach to deploy cloud resources. Internal and external evaluations of NIAC instances note good desktop responsiveness and adequate computing and storage capacity, and we seek to refine the prototype through further collaborations.

        Speaker: Mr Jonathan MacCarthy (Los Alamos National Laboratory (LANL))
    • P2.1 Characterization of Treaty-Relevant Events Zeremoniensaal & Marmorsaal

      Zeremoniensaal & Marmorsaal

      E-poster session with display of each e-poster on an assigned touchscreen

    • P2.3 Seismoacoustic Sources in Theory and Practice Zeremoniensaal & Marmorsaal

      Zeremoniensaal & Marmorsaal

      E-poster session with display of each e-poster on an assigned touchscreen

    • P4.4 International Monitoring System Sustainment Zeremoniensaal & Marmorsaal

      Zeremoniensaal & Marmorsaal

      E-poster session with display of each e-poster on an assigned touchscreen

    • Side Event - Working at the CTBTO - Recruitment Session 2 Forum

      Forum

      • 283
        Working at the CTBTO - Recruitment Session Forum

        Forum

        CTBTO is hiring professionals in STEM fields – Learn about CTBTO’s Recruitment Process
        Come and find out more about how to join the CTBTO! Visit us at the HR booth and speak with the CTBTO Human Resources team and learn more about CTBTO careers. You can also join us in our HR presentation where we will walk you through our recruitment process. CTBTO is hiring top talent across a wide variety of scientific and technical fields in seismic, radionuclide, hydroacoustic and infrasound technologies. There will also be a presentation focusing on students and young professionals interested in pursuing a career in these fields. We look forward to meeting you soon!

        Speakers: Ms Marta Fernandez de Mazarambroz (CTBTO Preparatory Commission), Ms Hema Kularatne (CTBTO Preparatory Commission)
    • Lightning talks: P2.2, P3.2, P3.6 Wintergarten

      Wintergarten

      • 284
        Theoretical Signature of a Cavern Created by an Underground Nuclear Explosion in 2-D Exploration Seismic Data

        The On-Site Inspections (OSI) are the final verification regime of CTBT. Its principal purpose is to detect if an underground nuclear explosion (UNE) has been carried out. Several geophysical techniques are used on a suspicious area to detect cavities, holes or devices that indicate the realization of a nuclear essay. One of these techniques is seismic reflection. There is scarce information in the literature about the seismic response of caverns created by UNEs, for this reason, in this work we use wave-propagation simulations to obtain the seismic signature of these types of caverns. We solve the elastic wave equation in the time domain using the spectral element method with fourth order basis functions and quadrilateral elements. We show the results for models with cavities and caverns corresponding to explosions of 1, 20 and 100 kilotons. In seismic traces we can observe the effect of these structures and we can see that cavities behave like points or diffractor bodies, depending on their sizes, whereas caverns, which are more complex structures, behave like two concentric diffractor bodies.

        Speaker: Jonas De Basabe (CICESE)
      • 285
        Resonance Seismometry: Search for Tiny Tot Underground Nuclear Explosion at Nevada Test Site

        Sonicona was contracted by the CTBTO to explore processing methods for the development of on-site inspection resonance seismometry capabilities. The motivation is to analyse seismic earthquake recordings to detect any anomalies indicative for a cavity or rubble zone caused by an underground nuclear explosion. We have developed the onset-delay method for strong earthquakes from regional to teleseismic distances. The underground disturbance will change the plane wavefield of seismic body waves. This change depends strongly on dimension, shape and depth of the rubble zone/cavity, and on all geological contrasts (heterogeneities, faults, etc.) in the surrounding area.
        The data set from Source Physics Experiments 5 and 6 at the Nevada National Security Site, the former Nevada Test Site, was used for the performed analysis. We were able to identify six anomalies which are mostly related to geology, and man-made underground structures, e.g. tunnel systems. Excluding these anomalies by external knowledge one anomaly remained, and could be related to the former UNE at Tiny Tot performed in 1965.

        Speaker: Mr Rolf Häfner (Sonicona GbR)
      • 286
        On-Site Inspection in Challenging Environments

        An on-site inspection (OSI) could be triggered in any environment. Environmental factors affect not only the signatures and observables of a nuclear explosion, but also the performance of the inspection team. Pursuant to the work on the OSI Action Plan 2016-2019 Project 1.5 on Operationalization of OSIs in Different Environments, this poster summarizes typical nuclear test explosion scenarios, key elements to be considered when developing OSI capability for different OSI environments and identifies challenging environments, i.e. mountainous areas, high seas, extreme climates and high/densely vegetated areas. Given the significant challenges that lie ahead for the development of OSI capabilities in challenging environments, it is envisaged that with the support of States Signatories and the involvement of the scientific community, a comprehensive OSI capability with strong climatic and environmental adaptability will be established.

        Speaker: Mr Feihong Kuang (CTBTO Preparatory Commission)
      • 287
        Fire Detection in an On-Site Inspection Area

        Fires are still a large concern in several countries due to the social, environmental and economic damages they cause. Computer vision is focusing a lot of their attention on improving object detection as one of the fundamental challenges in the field. The aim of this research is to propose a system to predicate or to detect a fire accident in an on-site inspection area in real time using a monitoring system using a deep learning based approach.

        Speaker: Ms Ahlam Khekan (University of Information Technology and Communication. Iraq)
      • 288
        Improvements in Methods and Chain of Custody for Measurements of Soil Gas Samples

        An important aspect of on-site inspection (OSI) is a rigid chain of custody, where the risk of human error is minimized. Since 2016, FOI has conducted four field campaigns in Kvarntorp (Sweden), with the aim of understanding the radioactive xenon background in uranium-rich soil. During these campaigns, we have developed methodologies for sample collection and analysis. During the most recent campaigns, we utilized Wi-Fi controlled soil gas samplers with automatic logging of relevant quality parameters (e.g. pressure, flow, volume, CO2, O2, Rn). Sample information and metadata are transferred to a digital field protocol and written to a RFID-tag when the collected air sample is compressed and transferred to a pressurized bottle. The SAUNA Field system, used for processing and analysis of the samples, has been equipped with a multi-sample inlet module that holds six bottles. The inlet automatically reads the information from the RFID tags, making it easy to start a measurement by selecting samples in the system GUI. This minimizes the risk of human error as well as ensures a tracking of the samples and all associated data. In this work, we aim to present lessons learned and how this could help to improve the chain of custody in an OSI context.

        Speaker: Dr Henrik Olsson (Swedish Defence Research Agency (FOI))
      • 289
        Innovation of the the Chain of Custody of Samples During On-Site Inspections

        A chain of custody (COC) is required in many laboratories that must analyse forensic materials and also to assure reliability of reported results. Tracking a reliable COC during an on-site inspection can be laborious but it is mandatory as it must assure that the evidence is authentic and traceable. The sampling methodology of the material, its transport and all the analysis steps as well people involved must be reported as information on the COC or chain of evidence. Although there is no limit to the number of transfers, it is crucial to keep this number as low as possible. A new solution for the future will be proposed: sample based COC, which could be innovative to eliminate problems with duplicates and/or splitting samples; location based COC based on RFID radio frequency identification; container based COC using electronic data key that can additionally detect any breach of integrity (evidence tampering).

        Speaker: Ms Antonietta Rizzo (Italian National Agency for New Technologies, Energy and Sustainable Economic Development (ENEA))
      • 290
        Automatic Xenon Calibration Generator

        Xenon spikes measurement is a key factor for Xe equipment calibration and a quality assessment/quality control programme for noble gas cluster. It is very important to have four Xe isotopes at the spike samples (Xe-131m, Xe-133, Xe-133m, Xe-135). The spikes are produced by contractors organized by the Comprehensive Nuclear-Test-Ban Treaty Organization. Unfortunately, due to very short half live of Xe-135 and small amount of Xe-133m in the spikes together with long spike delivery time and possible customs problems it is impossible to properly perform ROIs calibration for that isotope on site or even on the manufacturer's premises. Thus, now for detector calibration only Xe-133 and Xe-131m are widely used. Miscalculation during Xe efficiency calculations and ratios errors lead to some difficulties, such as false positive events, false alarms, etc. This poster shows new developments and first results of Automatic Xenon Generator based on 252Cf. This technique allowed to obtain xenon activity about 1000Bq, which was used for preparation of calibration sources by precision dosing method. The spikes are possible to milk at the Vienna International Centre or on site. The device is portable and has a user friendly interface for operation in automatic or manual modes. The poster will include all calibration process steps for different Xe equipment based on the four Xenon method.

        Speaker: Mr Nikita Popov (VXD LLC)
      • 291
        Radiation Monitoring of Territories Using Early Warning Systems

        Radiation early warning systems (REWS), which continuously transmit information about the level of radiation background, volumetric activity of radionuclides, meteorological conditions and other measured parameters to the central control post, can significantly reduce the risks of radiation threats to the population in controlled areas. The structure and composition of the existing REWS in European countries is analysed, the main principles for designing modern REWS are summarized and formulated.
        The results of the development of advanced alpha, beta and gamma radiation monitors for detecting radioactive contamination in the atmosphere and determining their activity are presented. Registration of gamma radiation in monitors is carried out either by a SrI2(Eu) scintillation detector (Ø1.5”x1.5”, ΔE≤3% on E= 662 keV) or an HPGe detector (30%) with Stirling cooler (ΔE≤2.0 keV on E=1332 keV), interchangeable without any monitors structural changes.
        To determine the concentration of alpha and beta radionuclides, the monitors use two independent spectrometric silicon detectors having an area of 600 mm^2 (ΔE≤25 keV on E=5.5 MeV). The second spectrometric channel is used for real time compensation of background gamma radiation in the beta energy range. The development results of big REWS based on alpha, beta and gamma advanced monitors (including for iodine and water) are presented.

        Speaker: Dr Andrey Vlasenko (Baltic Scientific Instruments)
      • 292
        Study of Silver Exchanged Zeolite Stability for Noble Gas Processes

        Noble gas processes are based on the use of adsorbent materials. Among them, silver-exchanged zeolites are the most efficient for Xe extraction. Before the use of a material in processes, it is crucial to ensure its performance, especially when use in systems operating 24/7. Ag-ZSM-5 (one of the studied exchanged zeolite) is an efficient candidate to enrich Xe, but long term stability seems to remain a topic.

        In our study, we assay to elucidate the relation between the structure of the material (Ag-ZSM-5 from different suppliers and synthesis) and the property (xenon uptake and deactivation). In our study, we investigated structure parameters that influence the properties that were already referenced in the literature. We expect the identification of the ideal structure will enable determination of the best adsorbent to use in a process.

        Speaker: Mr Célian Courtney (Commissariat à l’énergie atomique et aux énergies alternatives (CEA))
      • 293
        RASA 2.0: A Next Generation Aerosol Sampler/Analyser

        Lessons learned from 20 years of operation of the International Monitoring System for aerosol sampler/analysers have pointed the way to a new generation of aerosol monitoring equipment. Using new technology and following the sampling/analysis scheme developed for next generation xenon systems, new aerosol equipment will be more resilient in power failures, will give much better location in analysis, and perform better for very low signal levels and very high signal levels. Electrostatic collection uses less power per cubic meter sampled, and electrostatic collection efficiency could be reduced remotely for extremely high signal levels. A pair of gamma radiation detectors will deliver the required minimum detectable concentrations, but in shorter sample times (e.g. 8 h vs 24h), and a new method for packaging samples could give better field to laboratory agreement. Progress on new technology will be presented.

        Speaker: Dr Harry Miley (Pacific Northwest National Laboratory (PNNL))
      • 294
        Development and Validation of Coincidence Analysis/Quantification Software for Gamma-Gamma Coincidence Counting

        Gamma-gamma coincidence techniques are known to improve the detection of particulate radionuclides relevant for Treaty monitoring purposes. To that end, Pacific Northwest National Laboratory (PNNL, USA) has developed a novel γ-γ coincidence analysis and radionuclide quantification software package. The software’s execution has been tested for radionuclides relevant to Comprehensive Nuclear-Test-Ban Treaty and other radionuclides with complex decay schemes. This presentation discusses software’s details, challenges encountered in its development, and its experimental validation. The validation was performed by experimentally measuring 15 radionuclides (including Ba-140, La-140, and Y-88) using the Advanced Radionuclide Gamma-spectrometer (ARGO) located in the Shallow Underground Laboratory (SUL) at PNNL.

        Speaker: Mr Manish Sharma (Pacific Northwest National Laboratory (PNNL))
      • 295
        Identifying the Most Sensitive Beta-Gamma Coincidence Detector System for Radioxenon Measurements at the Comprehensive Nuclear-Test-Ban Treaty Organization's Radionuclide Laboratories

        GBL15, the UK’s noble gas certified Comprehensive Nuclear-Test-Ban Treaty Organization's radionuclide laboratory, supports the International Monitoring System (IMS) through the measurement of environmental radioxenon samples using beta-gamma coincidence spectrometry. GBL15 currently utilizes a system comprised of NaI(Tl) photon detectors and plastic scintillator electron-detectors in a SAUNA system to measure coincident emissions from four radioxenon isotopes of interest: Xe-133, Xe-135, Xe-131m and Xe-133m. A high-resolution electron-photon coincidence detector system comprising of high purity germanium (HPGe) detectors and a PIPSBox detector demonstrates improved discrimination between signals and less interference compared to the current system, although with a lower detection efficiency. Here we present the case for a HPGe-plastic beta-gamma coincidence detector system, which can demonstrate improved selectivity, but with greater detection efficiency. The minimum detectable activities for the radioxenon isotopes of interest have been quantified with various levels of interference.

        Speaker: Matthew Goodwin (Atomic Weapons Establishment (AWE) Aldermaston)
      • 296
        Development of a Modernized Radionuclide Laboratory System to Support the new Generation of International Monitoring Systems

        As the new generation of International Monitoring Systems (IMS) stations radioxenon are being deployed, the radionuclide laboratories are seeing an increase in samples sent for reanalysis. These samples include both radioxenon spikes and environmental backgrounds. Additionally, the sample volumes have increased with the new systems to further improve the minimum detectable concentrations. We have developed an upgraded radioxenon laboratory system that is capable of automatically processing four samples from a new generation IMS stations in series. The system leverages technologies implemented within the new generation of IMS stations to allow for better state of health tracking and automated measurement without the need for liquid nitrogen for the gas processing. In this presentation, we outline the design of the modernized U.S. radionuclide laboratory system and detail the improved capabilities for sample measurement. Additionally, we highlight the potential for increased sample verification with the updated processing and measurement system.

        Speaker: Michael Foxe (Pacific Northwest National Laboratory (PNNL))
      • 297
        Silicon Beta Cell Performance Improvements Using Silicon Photomultiplier Well Detectors for Beta-Gamma Radioxenon Systems

        Prior efforts in developing a silicon beta cell as a potential improvement to scintillating plastic in beta-gamma systems resulted in a design with high resolution, capable of resolving different conversion electron energies in the metastable radioxenons, but a higher threshold that cut off low energy X rays. Switching from a photomultiplier tube based NaI well detector to a low-voltage silicon photomultiplier (SiPM) based detector resulted in a significant improvement to the energy threshold from nearly 45 keV to below 30 keV. When combined with changes to the high voltage bias supply, energy thresholds on the beta cell have been reduced to below 22 keV. The SiPM well detector also drastically improved run-to-run reliability by eliminating noise dependence on beta cell positioning.

        Speaker: Johnathan Slack (Pacific Northwest National Laboratory (PNNL))
      • 298
        SEL63 – A xenon SAUNA lab System for Measurements of a High Diversity of Samples

        A SAUNA xenon lab system is operated at the Swedish xenon laboratory. The system has been running since 2009 and is used for a large variety of samples, ranging from subsoil samples with stable xenon volumes as low as 0.1 ml up to samples from the SPALAX-NG systems with a xenon volume of up to 6 ml. The high dynamic range of sample sizes puts special demands on the performance stability and calibration of the system. A good characterization of the system for all parts of the process is important to be able to minimize measurement uncertainties. This includes determination of the transfer losses during the sample process, GC-calibration for a wide range of xenon volumes and detector calibration for different sample sizes. Today the system is used for multiple purposes including participation in proficiency test exercises, measurement of samples from field exercises, re-measurement of samples from the Swedish xenon IMS-system and measurement of samples during development of new systems. The system and its calibrations together with results from some of these measurements will be presented.

        Speaker: Catharina Soderstrom (Swedish Defence Research Agency (FOI))
      • 299
        A new Prototype Detection System Based on the Beta-Gamma Coincidence Technique for Radioxenon Measurement.

        In this study, we develop a new radioxenon detection system based on beta-gamma coincidence to improve the sensitivity of detection in laboratory analysis. The designed system is a new prototype that is tested by injecting the 222Rn and its daughters (214Pb and 214Bi) as a beta–gamma emitter and also Xe-131m gaseous sources, which are in the interest of CTBTO. Further, the system is calibrated and checked using a Ho-166m source. This system consists of a NaI (Tl) as a gamma, X ray radiation detector, and a Silicon detector for the beta or the conversion electron detection. Silicon is used for improving energy resolution and minimizing the potential for memory effect compared to the scintillator detector. The list-mode multi-parameter data acquisition system is used to set up coincidence parameters. The efficiency of two detectors and MDA are obtained.

        Speaker: Ms Sepideh Alsadat Azimi (Amirkabir University of Technology)
      • 300
        Development of a Continuous Field Xenon Detection System

        Field studies of underground gas migration are an essential component of ongoing research to better understand how radioactive materials produced from underground nuclear explosions transport through and escape from the subsurface. Considerable research has been made in the past on understanding long term gas migration behavior driven by natural processes at field sites, but in recent years a greater focus has been placed on studying material transport driven by explosive events in early time. Scientists at Pacific Northwest National Laboratory are planning one such field experiment, which will utilize an injected radioactive xenon tracer driven by pressurized air in the subsurface to map out early time tracer arrivals at various sampling locations. As a critical component in this planned experiment, PNNL has developed a simple but robust xenon quantification system that allows for real time gas monitoring in the field as well as rapid switching between various sampling intervals. Here, the system concept is summarized, and evaluation is made of expected xenon detection sensitivities with respect to operational variables like sampling time, sample rate (i.e. gas pressure), temperature and radon background.

        Speaker: Christine Johnson (Pacific Northwest National Laboratory (PNNL))
      • 301
        Advanced Spectroscopy in Support of Nuclear Explosion Monitoring

        The radionuclide network of the International Monitoring System (IMS), operated by the Comprehensive Nuclear-Test-Ban Treaty (CTBT) Organization, is comprised of particulate and noble gas analysis. A variety of spectroscopic techniques have been developed and are in use to identify radionuclides which may be indicative of a nuclear explosion. Ongoing efforts to increase the sensitivity of measurements and reduce detection limits have seen the development of more advanced techniques. These include gamma-gamma coincidence spectroscopy to measure low level particulate samples and high resolution beta-gamma coincidence spectroscopy for radioxenon measurements. This poster will present a review of the latest published information on spectroscopic techniques in use and being developed in support of nuclear explosion monitoring.

        Speaker: Ayrton Jenkins (Atomic Weapons Establishment (AWE))
      • 302
        Next Generation Particulate Monitoring

        Operated by the Comprehensive Nuclear-Test-Ban Treaty Organization, the International Monitoring System is used by almost 200 nations to monitor for nuclear weapons tests. After more than 20 years, the network is mostly complete, however the technology utilized for the particulate monitoring component remains practically the same, despite a number of laboratories developing coincidence systems that can offer orders of magnitude improvements in detection sensitivity and reliability. Here we describe the status of the technology, and the advantages of implementing this within the International Monitoring System. Furthermore, the performance of a prototype system developed by the Comprehensive Nuclear-Test-Ban Treaty Organization is presented.

        Speaker: Dr Richard Britton (CTBTO Preparatory Commission)
      • 303
        Advanced Electrostatic Precipitator (ESP) for Radionuclide Particle Collection as Part of Integration into RASA 2.0

        Creare has designed, built, and tested an electrostatic precipitator (ESP) collection system for integration into the next generation of monitoring stations, RASA 2.0. The new system design has several significant improvements including advanced detectors, increased particle collection efficiency, lower power consumption, and potentially shorter collection times. Our advanced two stage ESP collects atmospheric aerosol particles on a flexible media. The particle-laden material can be folded compactly and presented to a coincidence detector system unlike the impact filter material used on the current RASA system. View factor modeling showed a large improvement moving from a wraparound detector system to a sandwich coincidence detector system which can enable large reductions in sampling intervals. Our ESP system has previously demonstrated over two times the standard flow rate of the current RASA system at significantly low power consumption. At the nominal flow rate of the RASA system, our system consumes about an order of magnitude lower power while meeting CTBT requirements for collection efficiencies. We have demonstrated reliable material handling in a full-scale lab-based prototype, with up to one years’ worth of material loaded on the system. Our system also demonstrated on-the-fly changes of collection efficiency and flow rate.

        Speaker: Michael E. Swanwick (Creare LLC)
      • 304
        Lowering the High Purity Germanium Background Measurement at the Italian ENEA Noble Gas Laboratory

        The ability to evaluate the concentrations of radioactive noble gases in the atmosphere is very important because it represents a powerful early warning tool in the event of a nuclear accident. Since there are currently no laboratories capable of carrying out this type of assessment in our country, a specific system has been set up for sampling, concentration, separation and analysis of radioxenon in atmospheric samples with the aim of acquiring skills and abilities that could be transferred to the authorities responsible for radiometric surveillance. It will also allow us to assist control activities and alarm the population in case of a nuclear accident. In order to correctly evaluate an anomalous detection of radioxenon, it is it is essential to know the value and the trend of the environmental background in the area of interest. Due to low concentrations, our efforts have been directed mostly at the reduction of the MDA of our measurement system, trying to improve the sensitivity and reduce the background noise. The methods used and the precautions applied to obtain ever more accurate measurements will be explained. Future plans for improvements will be also presented.

        Speaker: Stefano Salvi (Italian National Agency for New Technologies, Energy and Sustainable Economic Development (ENEA))
      • 305
        Comparison of Xe-127 Measurements

        Recent reports have shown that unusual xenon radionuclides can show up in grown based xenon detection systems that lead to false hits on all four of the regularly monitored radionuclides (Xe-135, Xe-133, Xe-133m, Xe-131m). Potential sources of these unusual radionuclides could be high flux neutron sources or spallation neutron sources that are operated in the vicinity of current ground based collection systems. The development of detection algorithms for these unusual xenon radionuclides is needed to prevent false positive detections from diverting analyst time and resources away from potential legitimate radionuclide detections. The Idaho National Laboratory Noble Gas Laboratory has developed the capability to produce Xe-127. This radionuclide has never been utilized in an interlaboratory comparison exercise. This work carries out a limited interlaboratory comparison exercise to demonstrate the potential for introducing Xe-127 and other unusual xenon radionuclides into future laboratory comparison exercises.

        Speaker: Mr Troy Robinson (Idaho National Laboratory)
      • 306
        SAUNA Qb - Performance of the National Radioxenon Array in Sweden

        The world´s first radioxenon array has successfully been installed in Sweden. The array consists of five detecting sensors (SAUNA Qb) which have been in operation for about two years. Compared to other radioxenon systems, the units are less expensive and easier to install and maintain. The cost of the entire array is similar to one single state of the art system. The individual sensors are less sensitive than a state of the art radioxenon system, but when combined, the aggregated verification performance can be high. The measurement units in the array cover a large area, which can lead to more detections and a potential improvement of source location and categorization. In this work, we will present results from the installations, operation, maintenance and the lessons learnt so far.

        Speaker: Dr Lindsay Karlkvist (Swedish Defence Research Agency (FOI))
      • 307
        Xenon Collection and Purification from air in Three Types of Porous Materials

        Radioxenon monitoring systems are a crucial component of the International Monitoring System (IMS) for the verification of the Comprehensive nuclear-Test-Ban Treaty. They monitor the atmosphere for potential xenon releases originating from nuclear tests. The efficient collection and purification of xenon from air is essential for their detection capability. The first systems in the IMS used pre-purification techniques to remove moisture and CO2 followed by activated carbon columns to collect and further purify Xe. In some new systems, silver-exchanged zeolites have replaced some of the activated carbon columns due to their much higher Xe adsorption capacity at room temperature. Recent studies on a new class of porous materials, namely metal-organic frameworks (MOFs), have demonstrated high Xe selectivity over other gas components although in conditions different than for IMS applications. In the framework of the EU JA VII programme, the potential use of MOFs for Xe collection and purification from air for IMS applications was investigated for the first time. This work has been further expanded over the last two years. The resulting thorough comparison of the Xe collection and purification ability and the underlying material characteristics of two MOFs, two silver-exchanged zeolites and a reference activated carbon will be discussed.

        Speaker: Christophe Gueibe (Belgian Nuclear Research Center (SCKCEN))
      • 308
        A Small, Portable Electrostatic Precipitation Based Radio-Aerosol Monitor

        Atmospheric aerosol collection using electrostatic precipitation (ESP) promises power consumption roughly one order of magnitude lower than filter paper based collection methods. For monitoring radionuclides in the atmosphere, this translates to an order of magnitude improvement in system sensitivity for the same power consumed. Conversely, small portable systems are enabled with lower battery and solar power requirements for extended operation at airflow rates matching filter-based systems that are challenging to operate in the field for extended periods. PNNL is currently developing a small, portable ESP-based radio-aerosol monitoring system. This presentation will cover the system design, projected monitoring capability, and the current status of the system build and testing.

        Speaker: Martin Keillor (Pacific Northwest National Laboratory (PNNL))
      • 309
        Xenon International Acceptance Testing

        Xenon International is a next generation radioxenon monitoring system that was developed at PNNL and being manufactured at Teledyne Brown Engineering (TBE) to strengthen nuclear test monitoring and has recently completed Provisional Technical Secretariat (PTS) testing and was accepted as a qualified system for the International Monitoring System (IMS). Xenon International processes samples every six hours generating over 2.5 cc of xenon gas that is counted in a beta-gamma coincidence detector for 12 hours resulting in unprecedented detection limits for radioxenon isotopes. Phase 1 testing was conducted at TBE and Phase 2 was conducted at Schauinsland Germany at RN33 radionuclide station. Xenon International completed acceptance testing with >96.93% uptime, and routinely detected never-before seen radioxenon isotopes in an IMS station including Xe-125, Xe-127, and Xe-129m during Phase 1 of testing. This talk will discuss Xenon International performance during PTS testing and will discuss expected and unexpected radioxenon isotope detections.

        Speaker: James Hayes (Pacific Northwest National Laboratory (PNNL))
      • 310
        Obtaining Enriched Argon from an Air Mixture by Pressure Swing Adsorption Method

        This work presents the results of the development and experimental investigations of the sampling unit of the automated system for monitoring the Ar-37 content in the soil and the surface atmosphere. The adsorption and separation characteristics of materials for air separation and argon extraction from an air sample by the volumetric method have been studied. CaA (5A), PSA/VPSA (13XHP) NaX (13X), ZSM-5, and Ag-ZSM-5 zeolites, as well as coconut charcoal and activated charcoal were used as materials. Adsorption isotherms of the main air components (Ar, N2, O2) on these sorbents at room temperature in the pressure range from 0 to 10 bar were obtained. Based on the study, a two-stage system of pressure swing adsorption was created to obtain enriched argon. The argon concentration in the enriched flow was measured as a function of the filling, blowing, discharge, and regeneration times, sorbent types, and adsorber volumes.

        Speaker: Roman Alexandrov (All-Russia Research Institute of Automatics named after N.L. Dukhov (VNIIA))
      • 311
        Experimental and Numerical Study of Particle Size Manipulation for the Optimization of Particulate Monitoring Systems

        A methodology of particle grouping based on a mathematical model enables to induce manipulation of the particle size distribution using grouping and coagulation which leads, in turn, to the increase of filtration efficiency and detection ability of monitoring systems.
        This study was conducted as a combined theoretical and experimental one. The current prototype consists of an inlet of particles (diameter of microns and sub-micron), a wavy tube combining oscillations created by a rotating disk at the entrance. The purpose of this setup is to encourage the aggregation of sub-micron particles into larger particles to increase their filtering efficiency. The experimental results indicate particle grouping in the system. It is concluded that this concept can serve as a tool for enhanced filtering efficiency of the grouped particles and thus can lead to increased efficiency of the particulate monitoring system.

        Speaker: Mr Kobi Kutsher (Soreq Nuclear Research Center)
      • 312
        Compilation of the Latest Evaluated Decay Data for the CTBT Relevant and Background Radionuclides for γ ray Spectrometry

        The CTBT-relevant radionuclides were selected using decay data from around 1998 to 2000. Now, about 22 years after the selection, we have available evaluated decay data that are even more reliable than they were at that time. The latest evaluated decay data (half-lives, decay modes, γ-ray energies, and their emission rates) for the CTBT relevant 96 radionuclides and background 49 radionuclides in γ-ray spectrometry such as particulate monitoring were compiled. For the data compilation, decay data evaluation project (DDEP) data, which contains the latest evaluated data for radionuclides with high applicability, and evaluated nuclear structure data file data for radionuclides without DDEP data available were used. The comparison of the compiled data set and the data used for the selection of the CTBT-relevant radionuclides showed relative differences of up to 36 % for the main γ ray emission rate, up to 10 % for the half-life, and up to 0.1 % for the main γ ray energy. In addition to CTBT-relevant and background radionuclides, a compilation of γ ray data for 18 radionuclides used for calibration and quality control measurements of γ ray spectrometer was also prepared.

        Speaker: Mr Chushiro Yonezawa (Japan Institute of International Affairs)
      • 313
        A New Method for Analysing Daily Quality Control: Beta-Gamma Spectra for Checking Energy Calibration

        The radioxenon system gain stability is critical to provide accurate measurements of the activity. There are several different methods for processing daily quality control (QC) beta-gamma two-dimensional (2-D) spectra for checking energy calibration. Fitting to a template seems the most correct method for monitoring the calibration stability. The possibility of using a template for a 2-D spectrum has been investigated. The template is created using locally weighted scatterplot smoothing (LOWESS) of a 2-D LONG QC spectrum (a histogram). It is necessary to smooth out the LONG QC spectrum histogram. Daily fitting of the template to the QC spectrum using the weighted least squares method gives the “tweaking” factors of the gain shift. A number of calculations have been carried out based on the results of measurements of the MIKS QC source (Cs-137 and Ba-133). Different approaches have been compared. The template-fitting method provides the most stable results even with poor statistics.

        Speaker: Nikolay Sidorov (Dukhov Automatics Research Institute (VNIIA))
      • 314
        Identical Mother and Daughter Radionuclides Related to CTBT for Improving the Detection of a Nuclear Event

        One of the most important issues in radionuclide monitoring technology is the analysis of radionuclide data of the International Monitoring System (IMS). The number and concentration rate of CTBT-relevant detected radionuclides determine the possibility of a nuclear event occurrence in radionuclide monitoring. Fission and activation products being on the standard list of CTBT-relevant radionuclides, decay to nuclides which are stable or unstable. Some of these radionuclides decay to radionuclides which are also among the 83 CTBT relevant radionuclides. Considering the different decay reactions of these radionuclides in mother or daughter states, estimating zero time of a nuclear event can be improved by discriminating these two decays. In this study, CTBT-relevant fission radionuclides that decay to unstable radionuclides, which are among the 83 CTBT-relevant radionuclides, are the focus and their decays over time are investigated using Bateman equations in mother and daughter, and the combination of these states. Then, the ratio of concentration of intended radionuclides to fission radionuclides are obtained for two scenarios including radionuclides detection in daughter state or combination of mother and daughter. Finally, the occurrence probability of nuclear event and its time are evaluated in these two scenarios.

        Speaker: Ms Sara Azimkhani (Atomic Energy Organization of Iran (AEOI))
      • 315
        Radioxenon Uncertainty Model

        Measuring radionuclide releases from underground nuclear explosions is extremely challenging given the likely low release and increasing background releases. This becomes even more challenging when measurement uncertainties are not fully understood and can make decisions based on measurements questionable. The work presented here will lay out a holistic uncertainty model that includes terms ranging from the initial detector calibration to physics constants to counting statistics. The uncertainty framework is applicable at low counting statistics near or at background levels and, although the uncertainty framework is based upon United States developed systems, it will be applicable to a broader range of systems.

        Speaker: Dr Matthew Cooper (Pacific Northwest National Laboratory (PNNL))
      • 316
        Long Term Radioxenon Detector Background: First-year results

        Environmental radioxenon measurements for nuclear explosion monitoring use the net count method to determine activity concentrations and rely on detector sensitivities for each of the radioxenon isotopes. This method requires that a detector background measurement be made to account for environmental radioactivity and is only performed during the initial install or during a recalibration. Currently, there are no other standards for how often the detector background should be updated. We report on first-year observations of the backgrounds. The count rate of individual detectors and coincidence counts provide an important metric for identifying anomalies and the causes that could impact both the minimum detectable concentration of the system and the accuracy of the activity concentration measurement.

        Speaker: Dr Rose Perea (Pacific Northwest National Laboratory (PNNL))
      • 317
        Reconstructing Radioxenon Sources in a High Background Environment

        Isotopes of radioxenon are prevalent in the atmosphere and present a “background” signal which can make radioxenon detection analysis and event reconstruction analysis more difficult. In recent years advances in software have allowed for Bayesian reconstruction techniques to be applied to radionuclide detections to determine the source parameters. This work focusses on the effort to reconstruct radioxenon sources amongst a high background signal using novel event analysis techniques and inverse atmospheric transport modelling simulations. Here we define a background signal based on estimated nuclear reactor releases, combine a “real” signal, then reconstruct the source parameters using a software tool known as FREAR.

        Speaker: Matthew Goodwin (Atomic Weapons Establishment (AWE) Aldermaston)
      • 318
        Comparison of Methods for Analysis of Radioxenon Beta-Gamma Coincidence Spectra Using MIKS Data

        There are several methods for analysis of radioxenon beta-gamma coincidence spectra. The most important approaches to estimating the activity using beta-gamma coincidence spectra are the Net Count Calculation (NCC) and the Standard Spectrum Method (XeMat and ROI simultaneous fitting method). Within these approaches, algorithms differ in many ways and can provide different estimates of the activity. A comparison of different methods and algorithms has been carried out in this study. Activity and MDC calculations using different methods were performed and the results were compared. Evaluations have been made using real data from the MIKS. It has been shown that if the count rate is high, all methods are consistent and similar, but if the statistics are poor, simultaneous fitting and matrix algorithms using a priori information are preferable.

        Speaker: Nikolay Sidorov (Dukhov Automatics Research Institute (VNIIA))
      • 319
        Investigating how SRS Fields can be used for Identifying Samples that may have Received Radioactivity from the Same Release Event as a Level 5 Sample

        Samples from International Monitoring System (IMS) stations which contain multiple CTBT-relevant radionuclides with abnormal activity concentrations (Level 5 for particulates) are sent to IMS radionuclide laboratories for further analysis. Since a reanalysis of spectra at IMS radionuclide laboratories might enhance the reliability of analysis results, it is proposed to investigate a method that can be used to identify potentially associated samples (that are most likely not categorized as Level 5) at the same or at neighbouring stations that may have received radioactivity from the same release event as the Level 5 sample. We investigate the methods to associate the Level 5 samples at an IMS station with the other samples at the same and at neighbouring stations using the source-receptor sensitivity (SRS) fields produced routinely for each sample by atmospheric transport modelling (ATM). This investigation can help to determine a suitable method for adding associated samples to the Standard Screened Radionuclide Event Bulletin (SSREB) of a Level 5 sample. This method can also be used to implement the triggering condition for sending samples to IMS radionuclide laboratories which may contain radioactivity from the same release event.

        Speaker: Mr Yuichi Kijima (CTBTO Preparatory Commission)
      • 320
        Investigation on Sample Association Using Decay Consistency Analysis for Consecutive Level C Samples and Prior/Post Level B Samples

        For the enhancement of International Data Centre products, specifically, the Standard Screened Radionuclide Event Bulletin (SSREB), an important step is to establish methods to associate the detections of CTBT-relevant nuclides in different samples with the same release to characterize its source for the purpose of nuclear explosion monitoring. Episodes of anomalous activity concentrations at the International Monitoring System (IMS) radionuclide stations are the first guess for being related to the same release. For multiple isotope observations, the consistency of their isotopic ratios in subsequent samples with radioactive decay is another plausible hint for one unique release. We show case studies of consecutive Level C samples and prior/post Level B samples used to demonstrate the effectiveness of sample association, whereas atmospheric transport modelling (ATM) is applied to identify the air masses that link the release to multiple samples. This approach forms the stepping stone to defining analysis procedures and criteria for automatic sample association for the SSREB, which is relevant for expert technical analysis.

        Speaker: Mr Yuichi Kijima (CTBTO Preparatory Commission)
      • 321
        Isotopic Ratio Distributions of Radioxenon at International Monitoring System Radionuclide Stations Using Emissions from Nuclear Facilities with Decay Correction Based on the Atmospheric Transport Time Distributions Between These Facilities and Stations

        The isotopic ratios of radioxenon can be useful for discrimination between CTBT-relevant radioxenon detections and civil nuclear facilities. In this presentation, the isotopic ratio distributions of emissions from the civil nuclear facilities, are evaluated first in order to test and demonstrate this methodological approach. Second, the source-receptor sensitivity fields calculated operationally with atmospheric transport modelling are utilized to determine the atmospheric transport time distributions between these facilities and the International Monitoring System (IMS) radionuclide stations. Then, the isotopic ratio distributions that can be expected for measurements at IMS stations can be calculated by folding these two kinds of distributions (emission and atmospheric transport time) while applying the radioactive decay equations. Finally, we compare these calculated isotopic ratio distributions of measurements at IMS stations with the real isotopic ratio distributions of measurement at IMS stations. This investigation can help to develop methods for screening by distinguishing between normal (based on known sources) and anomalous isotopic ratios. It may also be useful for discrimination between CTBT-relevant radioxenon detections and estimated observations based on emissions from known nuclear facilities as part of the effort of developing a Xenon Background Estimation Tool (XeBET).

        Speaker: Mr Yuichi Kijima (CTBTO Preparatory Commission)
      • 322
        Sensitivity Analysis of Activity Concentrations to Effective Sample Position in International Data Centre Products Using the Monte Carlo Simulation

        The International Monitoring System radionuclide particulate systems of the CTBTO network are equipped with one of the following three system types: CINDERELLA, RASA and manual. Each system commonly involves sampling, decaying and acquisition processes. Whereas the entire processes are automatically conducted in both the CINDERELLA and the RASA systems, ensuring high reproducibility of the measurement geometry, manual systems require human interventions. During the acquisition process, specifically, the decayed sample is manually placed on the detector endcap by operators. Since a sample holder is not necessarily used at the stations, the repeatability of the measurement geometry can be compromised by the mispositioning of the sample, with the consequence of introducing bias in the calculated activity concentrations. This study aims at investigating the impact of variations in the sample positioning on the calculated activity concentrations of radionuclides in measured samples, using Virtual Gamma Spectroscopy Laboratory (VGSL), a Monte Carlo based simulation tool. Possible scenarios were simulated to investigate whether variability in sample positioning has a noticeable impact on the isotope quantification reported in International Data Centre products.

        Speaker: Seokryung Yoon (CTBTO Preparatory Commission)
      • 323
        Developments Toward a Radionuclide Event Computational Pipeline

        A new goal for radionuclide monitoring is inspired by what is done with waveform processing, to automatically create a radionuclide event bulletin, synthesized from multiple measurements across the radionuclide network. Network measurements are sequentially processed through detection, association, and finally assimilated in an event, which is then documented within a bulletin with supporting data products, ready for an analyst to review. The progress on this development will be reported.

        Speaker: Mr Brian Schrom (Pacific Northwest National Laboratory (PNNL))
      • 324
        Neural-Network Based Isotope Estimation with Simultaneous Curve Fitting

        Radioxenon is used to identify underground nuclear explosions by quantifying the amount and isotopic ratios of Xe-135, Xe-133, Xe-133m, and Xe-131m. Determining these concentrations requires knowledge of the detector performing the measurement and the accurate attribution of each measured decay. The current standard for estimating the activity concentration employs a beta/gamma coincidence histogram combined with 7 or 10 rectangular regions-of-interest (ROI). These ROI are specific to the detector type, based on the energy resolution and efficiency of the detector. We present an alternative method of count attribution which employs neural networks trained on simulated data to generate probabilistic assignment for each detected count. These networks are physics-informed and employ gaussian curve fitting to closely model the expected behavior of radiation detectors. This reduces the parameters (hundreds compared to hundreds of thousands in related work) and maintains explainability of the results. Our work demonstrates a method of incorporating machine learning into radioisotope detection that does not require faith in a black-box model.

        Speaker: Dr J.R. Powers-Luhn (Pacific Northwest National Laboratory (PNNL))
      • 325
        GRANDSim: A Geant4 Based Simulation Software for Detectors in use at CTBTO Radionuclide Particulate Systems

        The CTBTO International Data Centre (IDC) developed a novel Geant4 based Monte Carlo simulation software for HPGe detectors in use at particulate systems of the International Monitoring System (IMS). The software, dubbed GRANDSim (an acronym for Geant4-based RAdioNuclide Detector Simulation tool), allows to simulate both coaxial and planar detectors, and includes default definitions of standard measurement geometries and shielding configurations of the three technologies operated at IMS particulate systems. The software simulates efficiency calibration, isotopic response function and coincidence summing correction factors for any natural and anthropogenic radionuclides of interest. The physical model is automatically optimized by constraining simulation results against experimental calibration for non-summing energies.
        Simulated entities are used as support parameters in the automatic processing of daily spectra from IMS for: (a) improving the quality of efficiency calibration (by including coincidence summing corrections), (b) enhancing the nuclide identification results (by including summation peaks) which reduces the workload on analysts in interactive mode, and (c) ensuring reliable activity concentration results by including required coincidence summing corrections when applicable. In addition, GRANDSim simulates gamma spectra for mixtures of radionuclides with any activity concentrations.
        The contribution presents the key features of GRANDSim for HPGe detectors in use at particulate systems.

        Speaker: Abdelhakim Gheddou (CTBTO Preparatory Commission)