# CTBT Science and Technology Conference 2021 (SnT2021)

Europe/Vienna
28 June - Opening (Hybrid) in Hofburg Palace, Vienna, Austria 29 June to 2 July - Virtual conference
Description

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 sixth event in the CTBT: Science and Technology conference series, SnT2021 will bring together around 1000 scientists, technologists, academics, students, CTBTO policy makers, members of the media and representatives of organizations involved in research and development that is relevant to all aspects of Treaty verification.

Conference objectives:

• To identify scientific opportunities and methods for improving nuclear test monitoring and verification;
• To identify how scientific developments and cooperation can support national needs and frame policy objectives in support of the CTBT;
• To broaden and strengthen the engagement of scientific communities working in test ban monitoring, including young scientists, and to enhance geographic and gender representations of these communities;
• To support the exchange of knowledge and ideas between the CTBTO and the broader scientific community;
• To promote the wider civil and scientific applications of techniques and data used for test ban verification;
• To highlight the CTBT’s successful model for multilateral science diplomacy and cooperation.
The SnT Support Team
• Monday, 28 June
• 10:00 12:30
High Level Opening - session 1: High Level Opening Festsaal (Hofburg)

### Festsaal

The Comprehensive Nuclear Test Ban Treaty’s (CTBT) opened for signature 25 years ago. The tested and proven verification regime, built on an over 1 billion investment in the International Monitoring System (IMS), is nearly complete. While the norm against nuclear testing is well established, with recent ratifications by Cuba and Comoros, the Treaty is not yet legally and universally binding. This seeming paradox requires both outside-the-box approaches to achieve the long-sought political breakthrough, as well as scientific and technological advances to sustain, improve and maintain the valuable contributions of the IMS. To mark this important anniversary, the High-Level Opening Day of the Science and Technology Conference 2021 will: • reaffirm the CTBT’s achievements, in obtaining acceptance of a worldwide norm against testing and the technical advances of its verification regime and technologies. • outline the essential role of the CTBT in achieving a world free of nuclear weapons; and • take a journey across time including the CTBT’s origin, its multi-disciplinary present, and concluding with a vision for the future through the lens of artificial intelligence, space travellers, scientists, and the upcoming generation of leaders. • 10:00 SNT21@25th anniversary of the CTBT: Ceremonial Opening and Political Remarks 1h 10m Master of Ceremony: Ms. Sanam Shantyaei, Senior Journalist, France 24 High-level speakers in order of appearance: • Mr. Lassina Zerbo, Executive Secretary, CTBTO • Ms. Ghada Waly, Director-General of UNOV, delivering a message on behalf of the United Nations Secretary-General Antonio Guterres • Mr. Peter Launsky-Tieffenthal, Secretary-General of the Federal Ministry of European and International Affairs of Austria • Mr. Li Yong, Director General, UNIDO • Mr. Rafael Grossi, Director General, IAEA • Mr. Bruno Rodríguez Parrilla, Minister of Foreign Affairs of Cuba • Mr. Dhoihir Dhoulkamal, Minister of Foreign Affairs and International Cooperation, in charge of the Diaspora, of the Union of the Comoros • Mr. Stephan Klement, Ambassador, Head of the EU delegation in Vienna delivering a message on behalf of the High Representative of the European Union for Foreign Affairs and Security Policy, and Vice President of the European Commission • 11:10 Musical interlude 10m • 11:20 Facilitated dialogue on CTBT@25 years: Evolution of the CTBT, the Organization and its technologies & CTBT’s model function of inclusion and science cooperation 1h 10m Master of Ceremony: Ms. Sanam Shantayei, Senior Journalist, France 24 Co-Facilitator: Ms. Sabine Bauer, Special Assistant to the Executive Secretary High-level Speakers in order of appearance: • Mr. Jaap Ramaker, Ambassador of the Kingdom of the Netherlands and Chair of the 1996 CTBT Negotiations, and former Special Representative to promote the Ratification of the CTBT, 2004 - 2009 • Mr. Grigory Berdennikov, Ambassador Extraordinary and Plenipotentiary; Head of the Russian Delegation at the CTBT Negotiations; Deputy Minister of Foreign Affairs of the Russian Federation (1992–1993; 1999–2001), member of GEM • Ms. Jenifer Mackby, Senior Fellow, Federation of American Scientists • Ms. Anne Strømmen Lycke, Chief Executive Officer of NORSAR • Mr. Ernest Moniz, United States Secretary of Energy (2013-2017), Co-Chair and Chief Executive Officer of the Nuclear Threat Initiative (NTI) • Mr. Desmond Henry Browne, Lord of Ladyton, Secretary for Defence of the United Kingdom (2006-2008), Vice-Chairman of NTI and convener of the European Leadership Network for Multilateral Disarmament and Non-proliferation, member of GEM • Ms. Tarja Halonen, Eleventh President of Finland and GEM member and Champion for a Nuclear Test Free World towards a Nuclear Weapons free world • Mr. Ban Ki-moon, Eighth United Nations Secretary-General and Founder of the Ban Ki-moon Centre for Global Citizens CTBTO-CYG • Ms. Sitara Noor, Senior Research Fellow, Centre for Aerospace and Security Studies, Islamabad, Pakistan • Ms. Magdalene Wangui Wanyaga, Project Manager, SandRose Ltd, Kenya • Mr. Jaona Andriamampandry, Assistant Researcher, Institute of Geophysics and Observatory of the University of Antananarivo, Madagascar • 13:00 13:45 CTBTO Youth Group: Evolution of the SnT conferences: CYG dialogue with Executive Secretary Lassina Zerbo • 13:00 Evolution of the SnT Conference: CTBTO Youth Group dialogue with Executive Secretary Lassina Zerbo 45m Since we only see the slow emergence from the COVID pandemic, SnT 2021 has gone mostly virtual. The new format aims to stimulate rich discussions and to create the space for wider and more diverse participation, especially by the next generation of experts. This year’s conference is the sixth conference in the SnT series and coincides with the 25th anniversary of the CTBT since it opened for signature. The principal goal of the conference series remains unchanged – to create a multidisciplinary scientific platform attracting scientists and experts from the broad range of the CTBTO’s underpinning technologies. For an entire week over multiple sessions, they will review scientific and technological advances and anticipate which innovative technologies would further strengthen the Treaty and its verification regime. Since 2015, CTBTO Youth Group (CYG) members have participated in the SnT as speakers, citizen journalists, poster presenters and attendees. To highlight the importance of multi-disciplinary youth engagement, Dr Lassina Zerbo, Executive Secretary of the CTBTO, will engage in an interactive dialogue with the CYGs. Participants will be able to discuss the evolution of the SnT series, the role of youth and learn about the main highlights of the conference. • 14:00 16:30 High Level Opening - session 2: High Level Opening Festsaal (Hofburg) ### Festsaal #### Hofburg Master of Ceremony: Bethany Bell, BBC Foreign Correspondent • 14:00 Artificial Intelligence (AI) to Transform Nuclear Explosion Monitoring and Verification: Thoughts on Opportunities and What It Might Take to Get There. 45m Artificial Intelligence (AI) has the potential to revolutionize the very ways we live our lives and make our world more sustainable and equitable. Today’s AI based methods, which are still nascent and narrowly applied, are already providing means to innovate and impact everything including science, environment, energy, health, and climate. AI impacts the U.S. Department of Energy (DOE) across all missions, businesses, and operations, and has become central to accelerating scientific discovery and the development of transformational new technologies. The DOE, like the CTBTO PrepCom, needs trustworthy AI systems that are accurate with high confidence and proven to be unbiased and reliable. Working in collaboration with global partners, DOE – the largest sponsor of physical sciences in the United States and largest generator of Nobel-prize winning scientists in the world – is driving high-risk research and development to advance the science of AI to create AI-enabled technologies that fulfill these requirements. This presentation will highlight a number of examples of AI in practice at DOE today, emerging areas of interest, and insights on opportunities presented by AI for the CTBTO PrepCom, drawing on decades of experience developing cutting-edge science and technology capabilities to deter and detect nuclear explosive tests. Speaker: Mr Dimitri Kusnezov (Deputy Under Secretary for AI and Technology at the US Department of Energy) • 14:45 Musical interlude 10m • 14:55 Space science and technology for global sustainable development, peace, and security 1h 5m Space has become an indispensable tool for our way of life. Addressing global challenges requires utilization of all available assets and space is one. Overall, space has transformed society and is instrumental for sustainable development at large. Today, we are witnessing changes to the conventional ways of operating in space, unlocking an immense range of opportunities, but also leading to challenges, requiring immediate attention and resolution. The dramatic increase in the number and type of actors in space and the consequent rapid growth of satellites have strong implications on the space environment. The United Nations has served as a convener for deliberations on space affairs since the beginning of space activities and has been successful in addressing the most pressing issues. It provides a unique intergovernmental and global platform for the benefit of everyone. Proactive multilateralism within the UN serves not only to expand access to space, but to ensure responsible behaviour in space for the benefit of human mankind. Chaired by Ms. Simonetta di Pippo, Director UN Office for Outer Space Affairs Introductory keynote on “Monitoring our planet from space”: Mr. Josef Aschbacher, Director General of the European Space Agency Panellists (subject to further updates): • Mr. Marcos Pontes, Minister of Science, Technology and Innovation of Brazil, former air force pilot and first South American astronaut in space • Mr. Jean Loup Chrétien, a retired Général de Brigade in the Armée de l'Air de France and former CNES and NASA astronaut. He was the first Western European in space and the first non-American and non-Russian to perform an extra vehicular activity. • Ms. Ilaria Cinelli, AIKO Space Autonomous Missions, Mentor of Space4Women network of UNOOSA, president of the Aerospace Human Factors Association • Ms. Zainab Azim, Co-Founder of G.I.V.E and Youngest Member of Virgin Galactic's Future Astronaut Program • 16:30 16:45 Interlude 15m • 16:45 17:45 EU-CTBTO panel discussion on Youth: Securing a nuclear test-free world for Youth and the next generations • 16:45 Securing a nuclear test-free world for Youth and the next generations 1h The European Union and the Comprehensive Nuclear-Test-Ban Treaty Organization enjoy a long-lasting partnership, underpinned by the EU’s political commitment to promote the universalization and the entry into force of the CTBT. The extra-budgetary support received over the past ten years from the European Union averages almost 30 mio EUR. Under specific focus has been the EU staunch support to the CTBTO work on engaging the next generation of experts through the CTBTO Youth Group, which bring together over 1200 young people from over 115 countries to advance with the EU imperative of strengthening international cooperation. The EU-CTBTO panel will examine how the cooperation between the EU and the CTBTO has contributed to the CTBTO efforts to engage youth in amplifying the efforts to advance the CTBT entry into force, strengthen their capacities in the nuclear non-proliferation and disarmament spheres and move a step closer to the EU’s commitment of a world without nuclear weapons. It will also discuss the main requests and suggestions from youth to policy makers on advancing the CTBT. Moderator: Ms Maria Chepurina (CTBTO Preparatory Commission, Vienna, Austria) Welcoming remarks: • Mr. Lassina Zerbo, Executive Secretary, CTBTO Panellists: • Mr. Stephan Klement, Ambassador and Head of the EU delegation in Vienna and Permanent Representative to the Vienna International Organizations • Ms. Leena Al-Hadid, Ambassador of the Hashemite Kingdom of Jordan to the Vienna based International Organizations and CTBTO • Ms. Marjolijn Van Deelen, EU Special Envoy on Non-Proliferation and Disarmament • Ms. Yeseul Woo, CTBTO Youth Group • Mr. Alan Juarez, CTBTO Youth Group • Tuesday, 29 June • 09:00 12:00 T1.1 e-poster session: T1.1 - The Atmosphere and its Dynamic T1.1 Convener: Mr Pierrick Mialle (CTBTO Preparatory Commission, Vienna, Austria) • 09:00 12:00 T1.1 e-poster session: e-poster session - T1.1 - The Atmosphere and its Dynamic Online #### Online T1.1 Convener: Mr Pierrick Mialle (CTBTO Preparatory Commission, Vienna, Austria) • 09:00 Observing military aircraft activity with the Romanian infrasound arrays 15m Presently, National Institute for Earth Physics operates two infrasound stations deployed on the Romanian territory: IPLOR 4-element array of 0.6 km aperture, and, under cooperation with AFTAC (USA), BURARI 6-element array of 0.7 km aperture. As many military bases are deployed across Europe and Near East region, signals from supersonic aircraft activity are detected routinely at the Romanian infrasound stations. These signals are observed from short/local ranges (140 km) to long-distance ones (2200 km). Several directions of interest were identified: NW (North Sea, Germany), NNW (Norwegian Sea, Northern Norway), NNE (NE Ukraine- NW Russia), SSE (Aegean Sea), SE (Turkey, Sinai Peninsula). Moreover, the two arrays frequently observe supersonic jets flying from military bases located in Romania. Sonic booms generated by military aircraft could be localized by cross bearing the detections of IPLOR and BURARI arrays. The information released on military exercises and LEB bulletins is used to validate the locations. At local distances, the sonic boom appears as an infrasonic pulse dominated by high frequencies (above 1 Hz), while, for long-ranges, lower frequency drops below 1 Hz as the higher frequency components are rapidly attenuated. Statistical analysis of wave parameters (trace velocity, azimuth, frequency, amplitude) shows seasonal and daily variations. Speaker: Ms Daniela Ghica (National Institute for Earth Physics (NIEP), Magurele, Romania) • 09:15 Graphic User Interface "Infrasound event analyzer" 15m Infrasound is one of three waveform technologies of the Comprehensive Test Ban Treaty (CTBT) verification regime. The International Monitoring System (IMS) network records manmade and natural sources of infrasound signals (bolides, spaceflight activity, sonic booms, volcanic eruptions, quarry blasts, earthquakes...). To identify these sources we need to download and process data, and analysts then have to interpret results. The CTBTO provides us with the needed software, but experience and training are recommended. Our idea is to let analysts enjoy interpreting infrasound data without being obliged to manipulate different software. For this purpose, a Graphic User Interface called "Infrasound event analyzer" is under development by NDC-TN, in which NDC-in-a-Box software (nms_client,DTK-PMCC, DTK-GPMCC) are grouped and called on a click. Speaker: Ms Chourouk Mejri ep Boukari (Centre National de la Cartographie et de la Teledetection (CNCT), Tunis, Tunisia) • 09:30 The Global and Coherent Infrasound Wavefield: Recent Advances in Reprocessing the Full International Monitoring System Infrasound Data 15m We present recent advances and results of reprocessing the IMS infrasound dataset from its beginning until early 2021. A new implementation of the Progressive Multi-Channel Correlation (PMCC) algorithm enables characterization, with a single processing run, of coherent noise in log-spaced frequency with one-third octave bands from 0.01 to 5 Hz. Such an array processing algorithm enables better characterization of all received signals in their wave parameter spaces (e.g. frequency–azimuth, frequency–trace velocity). This, in turn, permits more accurate signal discrimination and source and propagation studies. The latest comprehensive reprocessing of the IMS infrasound database covers the period from January 2003 to December 2020; in the meantime, the number of stations has increased from 30 to 53. The obtained results clearly indicate a continuous spectrum of coherent signals at IMS stations within the 0.01 to 5.0 Hz frequency range, as well as the wave parameters’ relation to middle atmosphere dynamics. Also, more sources are identified when comparing the recent results with those of previous reprocessing approaches or the standard IDC products. Speaker: Mr Patrick Hupe (Federal Institute for Geosciences and Natural Resources (BGR), Hannover, Germany) • 09:45 The state of the atmosphere throughout the seasons: comparison of numerical weather prediction models for infrasound observations at regional distances 15m Since the year 2000 the German Aerospace Center (DLR) facility near Heilbronn, Germany, has conducted main engine tests of the European ARIANE-5 rocket. Infrasound signals from these tests have regularly been observed during the last two decades at IMS station IS26 at a range of about 320 km in easterly direction. While a majority of these tests produced signal observations when carried out during the winter season between October and April, there is an almost complete lack of observations during the summer season. When comparing numerical weather prediction models for summer and winter seasons, or times with detections or non-detections, then these models differ significantly in the sound speed profiles producing either a strong stratospheric duct or a lack thereof. This is also reflected by the effective sound speed ratio, mostly exceeding a value of 1 for detections and less than 1 for non-detections. However, a significant portion of profiles with non-detections, nearly a quarter or 20 out of 88 cases, show a sound speed profile that should enable infrasound signal observations. The reasons for the lack of observations are addressed in this study. Speaker: Mr Karl Koch (Federal Institute for Geosciences and Natural Resources (BGR), Hannover, Germany) • 10:00 Location of multi-infrasonic pulse sources based on acoustic momentum of propagation 15m To solve the ambiguation in corresponding signals from same sources recorded in different arrays, a multi-infrasonic sources location method is proposed. This method is based on the conservation of acoustic momentum in audibility zone during long-range infrasonic propagation in the atmosphere. In a rocket launch observation experiment, progressive multi-channel correlation method is utilized to calculate the azimuth of each signal in both arrays. Meanwhile, the conservation of acoustic momentum of each signal is also used to match the pulse sources received by both arrays, which facilitates to obtain true locations of infra-sound sources. The propagation total reflection of a pulse signal in continuously changing medium and the acoustic momentum are analyzed. The experimental results demonstrate the effectiveness of the proposed method. Speaker: Mr Wei Cheng (Institute of Acoustics, Chinese Academy of Sciences, Beijing, China) • 10:15 Detection and properties of local artillery infrasound 15m Acoustic-wave detection from man-made sources like explosions and artillery is of interest both for civilian and military purposes. Infrasound propagation from surface sources is controlled by a complex interplay between source location, winds, atmospheric attenuation, and topography. The seasonal and stochastic variability of stratospheric and tropospheric winds is known to play an important role in the detectability of infrasound on the ground. In particular, large wind-intensity variations occur between summer and winter months. However, the lack of high-quality observational datasets with good temporal coverage throughout the year limits our understanding of the correlations between source characteristics, range-dependent atmospheric properties, and topography. Here, we take advantage of an extensive set of artillery exercises, conducted by the Norwegian Armed Forces in southern Norway throughout 2020, to constrain the detectability and wave properties at local distances. Up to 70 km distance, signals are generally observed when the atmospheric models include stronger lower-tropospheric winds (1-5km altitude) blowing in the direction of propagation. When cross winds dominate the wind field, low-amplitude infrasound arrivals are still observed in the acoustic shadow zone while not predicted by ray-tracing simulations, highlighting both model and propagation uncertainties introduced by small-scale wind heterogeneities and diffraction effects. Speaker: Mr Quentin Brissaud (Norwegian Seismic Array (NORSAR), Kjeller, Norway) • 10:30 Microbarometer arrays for the monitoring of extreme weather in a changing climate 15m Microbarometer arrays are used for the verification of the Comprehensive Nuclear-Test-Ban Treaty (CTBT) using infrasound waves. In addition, the microbarometers also measure pressure variations that are due to various meteorological phenomena with a resolution that exceeds that of typical barometers. The value of these high-resolution observations for the monitoring of extreme weather is discussed here, focusing on two recent extreme weather events in The Netherlands. Data from a dense observational network that includes lidar facilities and the Dutch microbarometer array network is compared to forecasts from global and regional weather forecast models to assess the forecast skill of the state-of-the-art weather models. The first-order agreement suggests that microbarometer arrays could provide valuable data for the development of next-generation weather forecast models. Such developments are useful for Early Warning Centers that report on severe weather outbreaks that can be disruptive for society and which are expected to occur more frequently in a changing climate. Speaker: Mr Jelle Assink (Royal Netherlands Meteorological Institute (KNMI), De Bilt, the Netherlands) • 10:45 On the use of dense seismo-acoustic network to provide timely early warning of volcanic eruptions 15m The Stromboli volcano is known for its persistent explosive activity, with hundreds of explosions every day ejecting ash and scoria up to heights of several hundreds of meters. Such a mild activity is however punctuated by lava flows and major explosions that represent a much larger hazard. On July 3 and August 28 2019, two paroxysmal explosions occurred at Stromboli, generating an eruptive column that quickly rose up to 5 km. Due to an absence of notification of the eruption, the Toulouse Volcanic Ash Advisory Center (VAAC) emitted an advisory to the civil aviation with a two-hour delay. The various processes of this event were monitored by infrasonic arrays up to distance of 3700 km and by the Italian national seismic network at range of hundreds of kilometres. Using state-of-the-art propagation modeling, we identify the various seismic and infrasound phases for precise timing of the eruptions and volcanic source characterization. Integrating national seismo-acoustic stations to the global infrasound International Monitoring System network opens new perspectives in volcano monitoring for hazard assessment by providing timely early warning of large eruptions. Speaker: Mr Alexis Le Pichon (Commissariat à l’énergie atomique et aux énergies alternatives (CEA), France) • 11:00 Comparison of forward and backward source-receptor sensitivities for atmospheric inverse modeling using the HYSPLIT model with the Cross-Appalachian Tracer Experiment (CAPTEX) field experiment measurements 15m Based on observations from monitoring stations or other platforms, unknown atmospheric pollutant emission sources, including source location, strength, and temporal variations, can be estimated using inverse modeling techniques. In such applications, 3D-particle Lagrangian dispersion models are usually employed, and the source-receptor sensitivities are calculated in either forward or backward modes for the source term estimation. While specifics of a given application may suggest a preference for one mode over the other, both forward and backward approaches can generally be applied for the inverse modeling. However, differences are often found in the inversion results between analyses based on forward and backward methodologies. In this study, we use the Cross-Appalachian Tracer Experiment (CAPTEX) field experiment as a test case to compute the source-receptor sensitivities between the known sources and air samples collected at 84 measurement sites. The differences between the forward and backward sensitivities calculated using the HYSPLIT model will be presented. The impact of the differences between the two approaches on the source term estimation results will be discussed. In addition, the underlying causes of the sensitivity discrepancies between the forward and backward approaches will be investigated and discussed. Speaker: Mr Tianfeng Chai (University of Maryland, College Park, Maryland, USA) • 11:15 Deep-learning for converting noise into knowledge 15m While awaiting signals from a nuclear test, the International Monitoring System (IMS) routinely detects many events that are attributed to atmospheric processes and referred to as perturbators or noise. These events, known to cause false detections, are an important source of difficulty in the network processing operated at the International Data Center (IDC). Because many thousands of events are recorded per day, recent efforts have been made in developing probabilistic inference for network processing and more recently, for estimating the energy. All these approaches, however, are based on priors that are poorly constrained, and/or extremely simplified propagation models, that are known to exhibit persistent shortcomings. In this work, we introduce a new hybrid framework to derive prior probability models from waveform modeling and take advantage of events accumulated in the analyst-reviewed bulletin. This approach is based on using current state-of-the-art propagation models in combination with a data-driven machine learning tool to model the remaining residual that is hidden in data. This approach presents two significant innovations: (1) the capability of converting perturbators into information, thereby providing a physical basis for the priors and (2) the opportunity to incorporate on a daily-basis additional atmospheric data in the priors. Speaker: Mr Christophe Millet (Commissariat à l’énergie atomique et aux énergies alternatives (CEA), France) • 11:30 Characterization of diurnal cycle of rainfall over peanut basin in Senegal 15m In this study, the diurnal variation of the rainfall amount, frequency and intensity, and the rainfall with different durations, as well as its intra-seasonal variability are analysed using rainfall data from 18 stations over Ndiaganiao (area located in western Senegal) during the period 2007-2015. Our results show that the mean rainfall amount and frequency peaks are observed around 1800 GMT for the whole season, while the intensity peak is observed between 1300 and 1400 GMT. It was also shown a strongest spatial variability with intensity compared to amount and frequency. Analysis of duration of rainfall events shows a higth occurence (up to 80\%) of short duration (1 – 3 hours) and these events are the main contributors (75\%) to the rainfall amount. However, the most intense events have a longer durations (4 – 5 hours). Finaly, our results show a strong intraseasonal variability of diurnal cycle in term of amount, frequency and intensity. Indeed, rainfall events occur between 1200 and 1400 GMT during the installation phase of the West African Monsoon (WAM) in June. In the height of the WAM (August-September), the amount and frequency show a similar feature with a peak observed around 1800 GMT. Speaker: Mr Cheikh Modou Noreyni Fall (University Cheikh Anta Diop of Dakar, High Polytechnic School of Dakar, Dakar Senegal) • 11:45 A novel approach for the reconstruction of microbarom soundscapes 15m In this study, a comparison is made between in-situ infrasound recordings in the microbarom band and simulations using a microbarom source model. The recordings are obtained by the 'Infrasound-Logger' (IL), a miniature sensor that has been deployed as biologger near the Crozet Islands in January 2020. The sensors provide barometric and differential pressure observations that have been obtained directly above the sea surface. A method is introduced to appropriately account for all microbarom source contributions surrounding the IL, as the full field consist of multiple spatially distributed sources. In this method, range and frequency-dependent losses due to propagation in the atmosphere are accounted for. While the method relies on several assumptions, a good agreement can be observed: the reconstructed soundscape is found to be within +- 5 dB for 80% of the measurements in the frequency band of 0.1-0.3 Hz. The development of microbarom soundscapes is essential for a better understanding of the ambient infrasonic noise field. Earlier work has shown that such knowledge is useful for infrasonic remote sensing of the upper atmosphere. Moreover, insights in the ambient noise field will improve the monitoring of natural hazards and the verification of the Comprehensive Nuclear-Test-Ban Treaty. Speaker: Mr Olivier Frederik Constantinus Den Ouden (Royal Netherlands Meteorological Institute (KNMI), De Bilt, the Netherlands) • 11:45 A Synthetic Study to Determine Adequate Infrasound Network Configurations for Resolving Source Directionality 15m Sources including volcanic eruptions and buried explosions have been shown to produce directional infrasound radiation. However, infrasound sensor deployments generally consist of instruments placed on the Earth’s surface. Therefore, directional sampling of the radiated acoustic wavefield (especially at angles close to vertical incidence) is generally limited. This insufficient wavefield sampling may bias source size estimates, including mass flow rate for volcanic eruptions or explosion yield. Here we conduct a synthetic study with local infrasound sensors placed around a directional acoustic explosion source to investigate the configuration of infrasound sensors required to uniquely recover a directional source mechanism estimate. We use finite-difference time-domain methods incorporating rigid topography to obtain the numerical Green’s functions for each synthetic station. We invert these synthetics to determine if the prescribed directional source mechanism and source-time function can be retrieved for a variety of station configurations. We consider the influences of environmental factors (wind, temperature, noise), as well as the directionality strength and orientation. The optimal sensor configurations to best estimate acoustic directionality found in this synthetic study will help guide future deployment configurations around active volcanoes and anthropogenic explosions. Speaker: Ms Alexandra Iezzi (University of California, Santa Barbara, CA, USA) • 11:45 A vespagram-based approach to assess microbarom radiation and propagation models 15m This study presents a vespagram-based approach for comparison between infrasound data recorded at the ground and simulated microbarom soundscapes in multiple directions simultaneously. Data recorded during 2014-2019 at the IS37 station in Bardufoss, Norway, have been processed in the framework of velocity spectrum analysis in order to generate images that present a signal power depending on time and direction (vespagrams). Calculations were performed for several frequency bands within the 0.1 - 0.6 Hz range. The modelled microbarom soundscapes were smoothed to account for the frequency-dependent array resolution. The infrasound data processed and modelled microbarom soundscapes were compared in three different aspects: i) azimuthal distribution of dominating signal, ii) signal amplitude, and iii) ability to track atmospheric changes during extreme events such as sudden stratospheric warmings (SSW). The results reveal good agreement between model and data and demonstrate the ability of vespagrams to monitor the microbarom azimuth distribution, amplitude, and frequency on a seasonal scale, as well as changes during SSWs. The presented vespagram-based approach is computationally low-cost and can uncover microbarom source variability. There is also potential for near-real-time diagnostics of the atmosphere and microbaroms, especially when applied to multiple stations, e.g. exploiting the CTBTO International Monitoring System network. Speaker: Mr Sven Peter Nasholm (Norwegian Seismic Array (NORSAR), Kjeller, Norway) • 11:45 Assessing convection schemes sensitivity for predict Congo Basin future drought severity 15m This paper investigates the sensitivity of two cumulous convection schemes – Grell and Emmanuel – under RCP8.5 scenario drought severity over Congo Basin (CB). The analysis were conducted using a multiscalar drought indices, standardized precipitation index (SPI) for several time scale –3,6,12,24,48 months –during the decades 2021-2030 ; 2031-2040 ; 2051-2060, and 2071-2080. The results reveal that under condition “SPI < -1” Grell’s model – maximum CB grid points average rate of 17.1 months per decade (mth/dec) – presents severe droughts duration trends in CB grid points coordinates different to that of Emmanuel – with maximum CB grid points average rate of 18.3 mth/dec. Thereafter, under the condition “SPI < -2”, the intensification of droughts in Emmanuel’s model evolves gradually with a scale of duration by grid points less stable and more extensive – 6.5 mth/ dec – towards the southern part of CB, while the Grell’s model spreads randomly and less widespread over the CB area with a more stable and reduced duration in maximum average rate of 3.9 mth/ dec. Speaker: Mr Steve Yvan Nono Noutchie (University of Yaounde, Yaounde, Cameroon) • 11:45 Assessment of seasonal forecasts using North American Multimodels Ensemble (NMME) in Central Africa (CA). 15m This study examines the assessment of the seasonal forecasts of the North American Multi-model Ensemble (NMME) Project in Central Africa (CA) using deterministic and categorical methods focusing on the rainfall variable. This assessment is made for the June through August, March through May, and December through February seasons at 0-5 months, lead-times which are consistent with many regional climate outlooks. The precipitation observed and predicted by the NMME models has been classified into three categories (rainy, normal and dry). It can be seen that at lead 0 that the average of the multi-model set (MME) favorably represents the average seasonal rainfall in the sub-region. The Taylor diagram shows a promising result at lead0 with significant correlation coefficients greater than 85%. At lead 3, the coefficient values ​​are low compared to lead 0. Note that the probabilities of detection (POD) of the models are more significant for the different seasons (normal). As a result, NMME models appear to be a valuable tool that can provide some key seasonal characteristics up to 5 months in advance in the sub regions, which will allow forecasters to better take into account all the uncertainties linked to natural phenomena and the state of the atmosphere. Speaker: Mr Ossenatou Mamadou (University of Abomey-Calavi (UAC), Porto-Novo, Bénin) • 11:45 Characterisation of the coherent infrasound sources recorded by the infrasound International Monitoring System station I48TN in Tunisia (Mines & Quarries) 15m The I48TN is one of the 60 International Monitoring System (IMS) stations of the Comprehensive nuclear Test Ban Treaty Organization (CTBTO) characterized by its location in the heart of the IMS Infrasound network (Figure 1.a). The ability of the IMS infrasound network to detect atmospheric nuclear explosions and other signals of interest is strongly dependent on station‐specific ambient noise. This ambient noise includes both incoherent wind noise and real coherent infrasonic waves. This abstract will focus on defining and characterizing the mines and quarries in the region as the most important real coherent infrasonic noise to I48TN in order to provide the infrasound data analyst with the most important local coherent infrasound sources in the region (mines and quarries) as recorded by I48TN and also to demonstrate how useful is the synergy between Infrasound and seismic data for the characterization of the acoustic sources. DTK_GPMCC, and DIVA software are used to perform this study (Cansi, 1995; Le Pichon et al., 2010). Also, Geotool software from the International Data Centre (IDC) will be used to analyse KEST seismic data. The result of this study will allow to characterize the most important coherent local infrasound sources (mines and quarries) for I48TN. Speaker: Mr Abdelouaheb Agrebi (CTBTO Preparatory Commission, Vienna, Austria) • 11:45 Characterization of the 4 August 2020 Beirut explosion from the infrasound component of the IMS network 15m The 4 August 2020 tragic Beirut ground truth explosion is of great interest to test the infrasound component of the IMS network, especially in terms of localization accuracy and energy estimation. Although the event was detected by five infrasound IMS stations located from 2 400 km (I48TN, Tunisia) to 6200 km (I11CV, Cape Verde), the early location capability from such a sparse network remains limited. Indeed, the spatial distribution of the remote detecting stations tainted by variable background noise levels, coupled with the relatively high uncertainties associated to the atmospheric parameters in the middle atmosphere, make the accurate localization estimation of such medium size events very challenging. We will show in this presentation that even if meteorological institutes can now provide high spatial and time resolution operational products (1h in time and 0.25° in space) at a global scale up to 80 km altitude, the final localization uncertainties remain quite high using infrasound-only data. Examples of full-wave modelling performed from ECMWF analysis and forecasts products, that the IDC distributes to Member States, will be shown to illustrate that point. Such model effects on energy estimation will also be quantified and discussed. Speaker: Mr Julien Vergoz (Commissariat à l’énergie atomique et aux énergies alternatives (CEA), France) • 11:45 Construction and Evaluation of a Statistical Model of Seasonal Forecasts in Cameroon. 15m The objective of this study is to build and then evaluate a statistical model of seasonal forecasts in Cameroon. A study was carried out in the five agro-ecological zones of Cameroon with the test stations of Kaélé, Meiganga, Nkongsamba, Yaoundé and Kribi. This study consisted of developing statistical forecast models at each of these stations which were then evaluated first over their calibration period (1958-1987), then over an earlier period (1989-1993). It emerges from this evaluation that the sea surface temperatures so far used during the PRESACs explain "roughly" the rainfall in Cameroon and especially in the cities of Yaoundé and Kribi where the multiple correlations between the sea surface temperature and rainfall indices are 0.70 and 0.71 respectively. It also follows that the Hit Skill Score and the rate of coincidence between forecast and observed rainfall indices vary from 65% to 85% and 76.66 % to 90% respectively. No model has false alarms. Strong connections between rainfall in Cameroon and the oceanic areas of the Atlantic coast of Africa located on the course of the African monsoon, the engine of rainfall in the region have been established. These results argue in favor of exploring other predictors to improve predictions. Speaker: Mr Hermann Nana (University of Yaounde I, Cameroon) • 11:45 I-131 and Be-7 analysis around RN22 in Guangzhou 2016-2020 15m As an artificial radionuclide, I-131 rarely appears in a natural environment, while RN22 monitoring system sometimes finds I-131 each year in air samples, especially in winter. The highest I-131 activity is 3 Bq while MDC for HPGe is 0.08Bq. The Gaussian model is applied to backtrack a possible resource of Iodine near RN22. The activity of cosmogenic radionuclide Be-7 in air samples is concentrated below 50 Bq in summer while in other seasons it varies up to 200 Bq. 2016-2020 Be-7 activity varies in a similar mode. The correlation between Be-7 activity and wind speed, PM10 is analysed. Speaker: Mr Wanliang Chen (Guangdong Environmental Radiation Monitoring Center, China) • 11:45 InfraPy, InfraGA/GeoAc, and stochprop: open-source software tools for infrasound signal analysis and propagation modeling at Los Alamos National Laboratory 15m Infrasound research conducted at Los Alamos National Laboratory (LANL) in recent years has included development of tools for signal analysis, propagation modeling, and uncertainty quantification. Many of these tools have been licensed as open source software, made available for download at the LANL Seismoacoustics Github page (https://github.com/LANL-Seismoacoustics), and are utilized by scientists across the globe for a variety of national security, civil, and scientific applications. The InfraPy signal analysis suite includes state-of-the-art detection, association, localization, and yield estimation algorithms accessible through Python-based scripting and notebooks, a command line interface, as well as the InfraView graphical user interface. The InfraGA/GeoAc software is a propagation modeling tool capable of simulating the propagation of infrasonic signals through the atmosphere in the limit of geometric acoustics and includes a number of unique features such as eigenray identification, weakly non-linear waveform calculation, and propagation over realistic terrain. The stochprop library is an in-development tool that includes methods enabling quantification and reduction of propagation uncertainties for infrasound analysis. The capabilities of these tools and their application to recent seismoacoustic events of interest will be presented. Speaker: Mr Philip Blom (Los Alamos National Laboratory (LANL), Los Alamos, NM, USA) • 11:45 Infrasound analysis associated with the Beirut explosions recorded on 4 August 2020 15m An explosion was reported on the 4th of October in the Port of Beirut (Lebanon), by IMS infrasound stations. News reported that the explosion was due to a large quantity of ammonium nitrate stored in the port that exploded (equivalent to around 1.1KT of TNT). The infrasonic signal was observed by several infrasound IMS stations, among them the Tunisian one (IS48). Data was processed with DTK-PMCC software to categorize the wave parameters for other infrasound stations. Speaker: Mr Atef Blel (Centre National de la Cartographie et de la Teledetection (CNCT), Tunis, Tunisia) • 11:45 Infrasound from meteorological fronts and its possible generation mechanism. 15m Infrasound radiated during periods of weather changes is an almost continuous background against which infrasound monitoring of explosions in the atmosphere is carried out. In this work the results of study of temporal variations of the characteristics of infrasound (amplitudes, coherences, grazing angles, azimuths and horizontal phase speeds) detected during a passage of warm and cold fronts through the networks of microbarometers in the cities Dubna and Moscow are presented. The significant differences observed in the characteristics of infrasound from warm and cold fronts are discussed. Such differences must be taken into account when detecting infrasound precursors of atmospheric storms. A possible aerodynamic mechanism for the generation of infrasound caused by the turbulent air flow around the geometric irregularities of the surface of meteorological front is proposed. This work was supported by RFBR grants 18-05-00576, 19-05-01008. Speaker: Mr Igor Chunchuzov (Obukhov Institute of Atmospheric Physics, Moscow, Russian Federation) • 11:45 Infrasound propagation simulations using atmospheric fields from high-resolution global models resolving gravity waves 15m Small-scale atmospheric perturbations known as gravity waves (GW) are critical to infrasound propagation simulations as they alter the propagation path of the waves, causing detections at infrasound stations that remain unexplained when only large scale atmospheric features are considered. Therefore, it is important to investigate ways of accounting for these perturbations in the atmospheric fields prescribed in propagation models. Here, we use modelled atmospheric fields obtained in the framework of the Dynamics of the Atmospheric General Circulation Modeled on Nonhydrostatic Domains (DYAMOND) project. This international project, initiated by the Max Planck Institute for Meteorology (MPIM) and the University of Tokyo, describes a framework for the intercomparison of high-resolution global atmospheric models. It mainly focuses on tropospheric weather, but some models were run with a high enough top so that GW are resolved up to the stratosphere. Starting with different configurations of the Icosahedral Non-hydrostatic (ICON) model, we explore how differences in infrasound-related parameters (azimuth deviation, shadow zone, celerity) derived using a ray-tracing tool relate to differences in the resolved tropospheric and stratospheric wind and temperature fields. Lidar observations are used to assess the modelled fields and to bring ground-truth atmospheric specification for infrasound propagation simulations. Speaker: Mr Constantino Listowski (Commissariat à l’énergie atomique et aux énergies alternatives (CEA), France) • 11:45 Long-range infrasound detections from explosions occurred in the Mediterranean area in 2020 as tools to evaluate the IMS network detection capability 15m IS42 is one of International Monitoring System (IMS) infrasound stations, located in the Azores islands in the North-Atlantic Ocean. Stromboli volcano is located in a small Italian island in the Mediterranean Sea. It is probably the world's best-known volcano due its spectacular basaltic explosions interspersed by lava fountains up to 250 m occurring every ≈10 minutes. Following the far-field characterization of its continuous explosive activity on infrasound-based analysis, we present here IS42 detections at a source-to-receiver distance of ≈3,700 km and a back-azimuth of ≈76°. Beirut, located on the Mediterranean coast, is the capital and the largest city of Lebanon. On 4th August 2020 at 15:08 UTC, the city harbour was almost completely destroyed by an enormous explosion caused by the combustion of 2700t of ammonium nitrate. This event was detected in various IMS infrasound stations, including IS42, at source-to-receiver distances ranging from approximately 2,400 km to 8,900 km. We present here the IS42 infrasound detections from this event, as well as from other IMS infrasound stations and compare the detections obtained with the events listed in the Reviewed Event Bulletin (REB) of the CTBTO, in order to evaluate the potential of the IMS network the IMS network capability. Speaker: Mr Sandro Matos (Instituto de Investigação em Vulcanologia e Avaliação de Riscos (IVAR), Azores, Portugal) • 11:45 Nyepi Day Impact on Weather Parameters Measurement at Synoptic Observation Stations in Bali 15m Nyepi is a rare activity in the world that only exists in Bali, where all of human outdoor activities stop for a day. This study used Nyepi to measure its impact on changes in weather parameters measurement in Bali. The purpose of this study is to see the effect of Nyepi on the ratio of daily average temperature to duration of solar radiation as well as daily average air humidity at four synoptic stations in Bali. The data that we used are daily average air temperature, duration of solar radiation, and average air humidity from 1999-2020 on Nyepi. As a comparison, we used data from 2 days before and after Nyepi. Based on 22 years of data at the four location points, we obtained that the air temperature in the 5-day range fluctuates and shows a trend of decreasing daily average temperature during Nyepi for all stations. As for the daily average air humidity, the effect of Nyepi is only visible at the Ngurah Rai Meteorological Station as an increase. The average temperature to sunshine ratio during Nyepi, 2 days before and after Nyepi showed that the lowest ratio occurs at Denpasar Geophysical Station and Jembrana Climatology Station. Speaker: Mr I Putu Dedy Pratama (Indonesian Agency for Meteorology, Climatology and Geophysics (BMKG), Jakarta, Indonesia) • 11:45 Rapid automated detection, association, and location of remote volcanic infrasound using 3D ray-tracing and empirical climatologies 15m Explosive volcanic eruptions produce powerful infrasound signals that are frequently recorded by the International Monitoring System (IMS). We are developing and testing methodologies to detect, locate, and characterize volcanic infrasound globally using data from the IMS. Challenges remain in attributing an infrasound event to a particular volcano, in part because source locations can be offset due to the effect of stratospheric crosswinds. We build on the combined association and location brute-force, grid-search, cross-bearings method of Matoza et al. [2017, 2018], here implementing backazimuth deviation predictions from 3D ray-tracing with empirical climatologies (HWM/MSISE). We are exploring the utility of climatologies rather than operational weather hindcasts for rapid first-order computation (e.g., for near-real-time monitoring, reanalysis of large data archives). With individual event case studies of two similar Volcanic Explosivity Index (VEI) 4 eruptions in Chile (Puyehue-Cordón Caulle volcanic complex on June 4, 2011; and Calbuco volcano on April 22, 2015), and stations up to ~5000 km, we obtain source location improvements of 66 to 89.6%. Here we further test our method using a multi-decadal (2003–2019) dataset of observations of moderate explosive eruptions from volcanoes Yasur, Lopevi, and Ambrym (Archipielago of Vanatu), recorded from 399 to 670 km from I22FR (New Caledonia). Speaker: Mr Rodrigo De Negri (University of California, Santa Barbara, CA, USA) • 11:45 Research on infrasound location method based on wide area monitoring network 15m The international monitoring system (IMS) of the Comprehensive Nuclear Test Ban Treaty Organization (CTBTO) has basically completed the planned construction of 60 infrasound stations in the world. The general infrasound signal processing technology of IMS is the progressive multi-channel correlation (PMCC) method, which includes TDOA algorithm. The common limitation of location algorithm based on time delay estimation is that its basic model only considers one sound source. Under the condition of multiple sound sources, the estimation result is not very ideal, and it is a suboptimal estimation. The accuracy of time delay directly affects the positioning accuracy. The beamforming algorithm can be used to orient the position of multiple sound sources, which has good directional effect, good stability and strong anti-interference. The IMS infrasound monitoring station can be formed according to the principle of triangle positioning calculation. For multiple positioning groups, each positioning group is regarded as a subarray. The subarray adopts beamforming for orientation, and the large array adopts time delay estimation to determine the distance. Using the data monitored by the wide area infrasound monitoring network arranged by the IMS, the infrasound source is located by combining multi array and multi algorithm, so as to further improve the positioning accuracy. Speaker: Ms Hao Yin (Chemical Defense Institute, Beijing, China) • 11:45 Study of Some Thermodynamic Parameters during Pre-Monsoon in Bangladesh 15m An attempt has been made to calculate different thermodynamic parameters to check the severity of thunderstorms during the pre-monsoon season of 2013-2015 in Bangladesh. In this paper, 60 weak to severe thunderstorms events which were recorded by the Bangladesh Meteorological Department (BMD) are investigated. Lifted Index (LI), Showalter Index (SI), Total Total Index (TTI), Convective Available Potential Energy (CAPE) and Convective Inhibition Energy (CINE) are calculated to find out the most reliable index for indicating the severity. It is found that the CAPE (having magnitude of 1500 J/kg or more), SI (magnitude of less than -2) and LI (magnitude of less than -3) are the most important parameters for predicting the occurrence of severe thunderstorms and these indices have a significant skill of forecasting the occurrence of severe thunderstorms. Speaker: Mr Md Momenul Islam (Bangladesh Meteorological Department, Dhaka, Bangladesh) • 11:45 Unusual infrasound observations from the August 2020 Beirut explosion 15m On 4 August 2020, a warehouse of ammonium nitrate exploded in Beirut, Lebanon, leading to loss of life and property. Infrasonic signals from this event have been detected across the Middle East, Europe and North-Africa. The furthest IMS station that detected the signal was IS11 (Cape Verde) at over 6000 km distance. The features of the observed infrasonic signals were unusual for the time of year. (1) Signals with tropospheric celerities were observed at IS26 and IS48, the nearest IMS arrays to the west and northwest, as well as the national arrays in Hungary (PSZI) and Romania (IPLOR). (2) At IS26 and PSZI, curious trace velocity trends were observed, starting at high values and decreasing along the wave train, contrary to what is typically observed. (3) The fastest arrivals at IS26 and PSZI appear to have significant back azimuthal scatter. These observations suggest that the propagation conditions were more complex than a single stratospheric duct which is typical for mid-summer conditions in the Northern Hemisphere. It is hypothesized that the tropospheric phases interacted significantly with topography. This hypothesis is supported by wind and temperature forecasts derived from numerical weather prediction models. An analysis of the propagation conditions is presented. Speaker: Mr Jelle Assink (Royal Netherlands Meteorological Institute (KNMI), De Bilt, the Netherlands) • 11:45 Validating infrasound signal-parameter models using a global ground truth data set 15m The celerity-range model used for both association and location in the standard automatic and interactive analysis at the International Data Centre (IDC) of the Comprehensive Nuclear-Test-Ban Treaty Organisation, has not been updated for over 10 years. The NET-VISA automatic association algorithm (Arora et al., 2013) currently providing additional information to IDC analysts, is based on prior probability distributions learned from previous interactive analysis results. Improving the IDC model(s) should improve interactive analysis results, and thus over time improve NET-VISA performance for seismo-acoustic events. Whilst numerical acoustic propagation modelling may be used to provide both range and time dependent priors for signal parameters, ground truth data analysis is necessary for model validation. Using software developed to consistently analyse a global ground truth database, empirical models for celerity, backazimuth and duration have been constructed from 312 detections in the 0.32 – 1.28 Hz passband. The probability distribution for backazimuth is consistent with the NET-VISA backazimuth prior derived using seismo-acoustic events. Our results do not support the IDC model increase in stratospheric signal celerity at a distance of 20°; we look to provide a range-dependent model whose uncertainties reflect the lack of observations at these longer ranges. © British Crown Owned Copyright 2020/AWE Speaker: Ms Alexandra Nippress (AWE Blacknest, Reading, UK) • 09:00 12:00 T1.2 e-poster session: T1.2 - The Solid Earth and its Structure T1.2 Conveners: Mr Gerhard Graham (CTBTO Preparatory Commission, Vienna, Austria) , Ms Nurcan Meral Ozel (CTBTO Preparatory Commission, Vienna, Austria) • 09:00 12:00 T1.2 e-poster session: e-poster session - T1.2 - The Solid Earth and its Structure Online #### Online T1.2 Conveners: Mr Gerhard Graham (CTBTO Preparatory Commission, Vienna, Austria) , Mr Haijun Wang (CTBTO Preparatory Commission, Vienna, Austria) , Mrs Nurcan Meral Ozel (CTBTO Preparatory Commission, Vienna, Austria) • 09:00 Lithospheric Structure of Africa and Surrounding Regions Revealed by Earthquake and Ambient Noise Surface Wave Tomography 15m To advance the understanding of the tectonic processes shaping the African continent, we construct the first continental-scale shear-wave velocity (Vs) model of the lithosphere from the joint analysis of ambient seismic noise and earthquake data recorded by ~1529 seismic stations in and around Africa. We apply the widely used ambient noise cross-correlation and earthquake two-station methods to retrieve the Rayleigh-wave group and phase velocity dispersions which are jointly inverted for a new three-dimensional Vs model. The inclusion of short-period dispersion data from ambient noise allows us to obtain a more accurate model than previous global and continental-scale studies, revealing lithospheric structures that correlate well with known tectonic features. In sparsely instrumented regions of north-central Africa, our model provides seismic evidence for the existence of cratonic remnants beneath thick sediments within the Sahara Metacraton and reveals unique mantle upwelling beneath hotspots suggesting that they may be fed by unconnected plumes. The estimated crustal thickness varies among and within tectonic provinces and shows no clear evidence for the secular variation in crustal genesis. Our new model has the potential to serve as a reference velocity model for Africa and is useful for practical applications including monitoring of the Comprehensive Nuclear-Test-Ban Treaty. Speaker: Mr Adebayo Ojo (Geological Survey of Canada, Ottawa, ON, Canada) • 09:15 Triggering Mechanisms of Gayari Sector Avalanche, Pakistan 15m On 7 April 2012, a massive snow avalanche occurred in the north-western mountains of Pakistan, close to the Indian and Chinese borders. To mitigate its future hazard, different triggering mechanisms have been investigated in this study. The avalanche signal was clearly recorded on both infrasound and seismic stations, located at varying distances between 300 and 450 km. The avalanche occurred within the coda of a 2.8 magnitude deeper earthquake from the Hindu Kush region, located 560 km away. Although the size and impact on the avalanche might be small, the occurrence was part of the accelerated moment release (~ 50 % seismic moment release of total 2 days) three hours before the avalanche occurred. Cumulative seismic moment and peak dynamic stress show a significant increase a month before the avalanche. This sequence was stronger and had highest daily event rate, but interestingly the avalanche occurred within the reference seismicity, rather than the aftershock relaxation phase. The secondary process might be activated or triggering clock might be advanced during this sequence. The presence of cracks within the avalanche were further weakened by extremely low temperatures and accelerated the earthquake phase during 2012. Speaker: Mr Mohammad Tahir (Centre for Earthquake Studies (CES), Islamabad, Pakistan) • 09:30 Seismic and aseismic observations and self-similar theory 15m The postseismic slip that follows large earthquakes is typically a few tens of percent of the coseismic moment, while the postseismic slip following small earthquakes appears to be comparable to the moment. Here I estimate the postseismic slip following intermediate-magnitude earthquakes and find that it is intermediate between the two, about 40% of the coseismic moment. The variation in postseismic slip with moment suggests that earthquakes may not be self-similar: that the properties of earthquakes or the regions that surround earthquakes vary systematically with earthquake size.if this is true, it would reveal a global fact related the physical processes of earthquakes. Speaker: Dr Mohamed Alwahedi (National Center of Meteorology, Abu Dhabi, United Arab Emirates) • 09:45 Attenuation of seismic waves in the northern Appalachians of southeastern Canada 15m We investigate seismic attenuation characteristics of the Canadian portion of the northern Appalachians. Coda Q is determined using 389 earthquakes (1.8 =< M =< 3.9) recorded on four stations of the Canadian National Seismic Network (CNSN) in New Brunswick from 1985 to 2020. For comparison, we divide the study area into northern and southern portions, each with two seismic stations and 162 and 227 events, respectively. At lapse times of 12 to 60 seconds, coda Q at 1 Hz (Q0) at the two seismic stations in the region of northern New Brunswick that is closer to the seismically active Charlevoix seismic zone (including a M7 event in 1663) is 82 +/- 5 on average. In contrast, the two stations in southern New Brunswick have an average Q0 of 114 +/- 3. The lower Q0 value in the north in comparison with the southern part of the region is in agreement with Jin and Aki's (1988) finding that Q0 is lower in the vicinity of large earthquakes. Ongoing mapping of coda Q in the area using the CNSN stations is planned in order to contribute to the ongoing development of more accurate seismic hazard models. Speaker: Mr Amir Mansour Farahbod (Geological Survey of Canada, Ottawa, ON, Canada) • 10:00 Identifying suspect instrument intervals using midnight noise time histories 15m Instrument response issues are common in seismology, and they can hinder research. We use large data sets to develop models that will predict high-frequency seismic amplitudes, which requires extensive quality control. To identify response and station health issues, we have collected time histories of noise measurements near (but not restricted to) midnight to eliminate diurnal variations, and have manually determined time intervals that appear inconsistent with background behavior. We assign descriptive labels, but do not attempt to diagnose causes. We currently use results to discard data. To date, we have examined 39,260 channels from 11,105 stations, heavily weighted toward Incorporated Research Institutions for Seismology (IRIS) holdings, at bands between 1 and 8 Hz, finding 24,733 anomalous time intervals that represent 13% of the total inspected time range. The majority (90%) of these intervals are constant offset shifts, often bounded by known instrument changes, likely resulting from poor response documentation at one of many stages between the field and publication. We hope these results can be of use to our colleagues, and encourage community efforts to diagnose anomalous behavior, and fix poor responses. We also hope these results will support automation efforts, including application of supervised learning techniques. Speaker: William Scott Phillips (Los Alamos National Laboratory (LANL), Los Alamos, NM, USA) • 10:15 Towards building a ground motion data base to improve the seismic hazard assessment In Bolivia (Plurinational State of) 15m Seismic hazard assessment for any region in the world has become a very serious and difficult task for seismologists, civil engineers and decision makers. Probabilistic hazard studies are conducted at the Observatorio San Calixto (PSHBO-2019) to estimate the maximum peak ground acceleration integrating all available variables, however no strong motion time-series (waveform) were applied due to the limited equipment installed in the country. To solve this issue, since 2016 we started to compile and to convert the velocity frames from our IMS stations (LPAZ and SIV) and temporal seismic network installed in the country to have acceleration and displacement traces. These waveforms were pre and post treated to obtain the pseudo acceleration, velocity and displacement spectrum and they were tested with regional ground motion prediction equations in order to validate them for local use. A set of 80 earthquakes are presented that will contribute to the improvement of PSHBO-2019. Speaker: Mr Gonzalo Antonio Fernandez (Observatorio San Calixto, La Paz, Bolivia) • 10:30 International Data Center Magnitudes and Their Relation to International Seismological Center Magnitudes Using Data for Ethiopia and Eritrea Regions 15m Various type of magnitude scales are recognized for estimating the earthquakes size. Magnitude is one of the significant factors for a unified earthquakes catalog which is needed for seismic hazard assessment and disaster management. The variation in magnitude value from seismological agency to other stimulated the researchers to study the regression relationship between the magnitudes. The study area is located between latitudes 4⁰- 16⁰ and Longitudes 36 ⁰-42⁰ in the east Africa region. A selected number of events which has magnitudes ranges from 3 to 5.6 for the period between 2000 and 2020 were used to create the regression relations. In this research the standard least-square regression (SR) and orthogonal regression (OR) were derived to assess the relation between the international data center (IDC) magnitudes in addition to the international data center (ISC) magnitudes based on body wave magnitude (mb), surface wave magnitude (MS) and local magnitudes, these regressions were adopted to choose the best regression model. Finally, the conversion equations between magnitudes were constructed and determined for wide range about twenty years. Speaker: Ms Khalda Yassin Ibrahim Ali (Seismological Research Institute, Khartoum, Sudan) • 10:45 How reliable are moment tensors of small earthquakes? 15m Calculation of moment tensors of weak seismic events is challenging. Quite often we face a lack of stations and inaccurate velocity models. However information on moment tensors is important for understanding origin of the events (explosions, natural and induced earthquakes) and seismotectonic regime of the area. We re-analyzed two methods of retrieving moment tensors: (i) Inversion of amplitudes of P- and S-waves, and (ii) inversion of three-component full waveforms, complemented by first-motion polarities. The methods utilize different types of waves, different frequency bands, and different methods to calculate Green’s functions. We compare and discuss the methods in terms of reliability, efficiency and accuracy. The discussion is performed on examples of two weak earthquakes from Slovakian-Ukrainian border which appeared in April 2020, with local magnitudes 3.2 and 2.3. Speaker: Lucia Fojtikova (Earth Science Institute, Slovak Academy of Sciences, Bratislava, Slovakia) • 11:00 Analysis, Processing and Interpretation of the Gravity data between latitudes 15N-17N (Sudan) 15m A gravity analysis and Interpretation are carried out using data collected by Sun-Oil Company in the area west of Khartoum between latitudes 15◦ -17◦ N and longitude 30◦-33◦ E. The data released in a Bouguer anomaly map at scale of 1:500,000 and a contour interval of 5mgal.The target is to analyze and interpret the gravity data in terms of surface and subsurface geology. The qualitative interpretation includes the construction of second vertical derivative map, analytical upward, downward continuation and separation of residual and regional anomalies. The operation of the second vertical derivative and analytical continuation is thought to be as a filtering operations based on the linear filter theory. Five models are used to construct a depth to the basement map. Geological sections are drawn along five profiles passing through boreholes of Elmagad, Abu Hashim and Jebel Aulia. The result revealed that the negative anomalies are associated with the existence of the Cretaceous Nubian Sandstone sediments as in the cases of BagBag, Hummar and AbuDulu basins with maximum depth of 3000, 1000, and 1900 meters respectively. These basins are considered as parts of the Blue Nile Rift Basin that has been subjected to tectonic movements which affect the central Sudan Speaker: Ms Naila Mohamed Osman Babiker (National Center for Research, Khartoum, Sudan) • 11:15 The EOS’s broadband seismic network in Myanmar: installation, site classification, local seismicity reports and velocity structure studies 15m To study the earthquakes and better understand the tectonics in Myanmar, Earth Observatory of Singapore (EOS) has been collaborating with local seismic monitoring authority to install (30) broadband seismic stations. With the broadband collected data, we have used them to study the site classification, earthquakes relocation and constrain the velocity structure. We defined our EOS’s broadband seismic stations site classes by using the horizontal to vertical spectral ratio (HVSR) method from ambient seismic noise. We clearly identified some of our stations on the rock site such as; EW01, M024, EW07, M027 which have resonance frequency larger than 5.0 Hz. The resonance frequency less than 1.6 Hz are defined as soft soil class such as EW05, M008, M012, M022. This kind of classification is based on the National Earthquake Hazards Reduction Program (NEHRP) site classes. From the initial automatic location that we have selected and relocated ~1000 earthquakes which we found that all these local earthquakes well define the Indian slab beneath Myanmar region. Moreover, use selected teleseismic events located between 30 to 90 degree distance to image the Moho beneath our seismic stations using P-receiver functions (PRFs) and H-K stacking technique to get crustal thickness and Vp/Vs ratio. Speaker: Mr Phyo Maung Maung (Nanyang Technological University, Earth Observatory of Singapore, Singapore) • 11:30 Seismicity along the seismogenic zone of Algarve region (southern Portugal) 15m The present seismological study, focused around Algarve region, was carried out through a cooperation project between the Universities of Évora (Portugal), Lisbon (Portugal), Strasbourg (France) and the IPMA (Lisbon, Portugal). To locate the seismic events and find the local velocity structure of the epicentral area, the P and S arrival times at 38 stations are used (Geostar stations, telemetered network, U. Lisbon and IPMA stations). The data used in this study were obtained during the Algarve campaign, which worked, from January/2006 to July/2007. The preliminary estimate of origin times and hypocentral coordinates are determined by the Hypoinverse program. Linearized inversion procedure was applied to comprise the following two steps: 1) finding the velocity model using Velest and 2) simultaneous relocation of hypocenters and determination of local velocity structure. This work is expected to produce a more detailed knowledge of the crust structure over the region of Algarve, being able to identify seismogenic zones, potentially generators of significant seismic events and the identification of zones of active faults. Speaker: Ms Assia Dib (Université des Sciences et de la Technologie Houari Boumedien, Algiers, Algeria) • 11:45 3D tomography of the crustal structure of the central part of Madagascar 15m Madagascar has never had a big earthquake until now. The biggest earthquake had a magnitude of 7 Richter, and not on land but in the ocean. The highest magnitude on land was below 6 Richter. The central part of the big island is the most active seismically. It can be clustered into three zones. Two of them are a Cenozoic volcanic area, which are Itasy and Ankaratra, from the north-west and the south respectively. The last seismically active zone is Alaotra, at the north-east part, and at the Alaotra-Ankay rift composed by normal faults. Many scientific articles say the volcanoes in the central part are already extinct and some say there have been recent eruptions, which means they are dormant volcanoes. The seismic map reveals that the epicenters tend to line up from the volcanic area of Ankaratra to Itasy and expand till Bongolava. A 3D tomography of this zone was done, with the permanent stations including the CTBTO station, to determine and study the structure of the crust which is thinner than the coastal areas. Speaker: Mr Ramarolahy Rina Andrianasolo (Institute and Observatory of Geophysics of Antananarivo (IOGA), Madagascar) • 11:45 About Regularities of Seismicity of Western and Central Uzbekistan 15m Space-temporal distribution of seismic activities in Western and Central Uzbekistan is considered. Four groups of strong earthquakes in the regions were analyzed. The pattern of redistribution of the accumulated tectonic energy in the form of seismic activity in the regions is revealed. In a west-east direction, an increase in the depth of earthquakes is noted. Deviations from the regularity of grouping of strong earthquakes in the seismic regime of the region is found. Periods of seismic activity of the Western Tien-Shan in the Asian part of the Mediterranean-Asian seismic belt showed their regional and planetary synchronization. Late periods of seismic activity of Western Tien-Shan had been explained by low level magnitude М=5.3 of main shocks in the group. Study of the seismic regime of the region where the triple Gazli earthquakes of 1976 and 1984 occurred, М=7.0-7.3 were probably preceded by triggers. Natural triggers: active processes of cracking (large cracks up to 100 km in length) observed in 1965; small mud volcanoes "griffons"; the absence of significant earthquakes in the Gazli region more than 40 years. Technogenic triggers: a permanent 40-year operation of "Gazly" gas fields: two nuclear explosions of 1966, 1968, which occurred near the Gazly earthquakes of 1976, 1984 that have a tectonic nature. Speaker: Ms Makhira Usmanova (The Institute of Seismology of the Academy of Sciences of Uzbekistan, Tashkent, Uzbekistan) • 11:45 Ambient Noise Tomography (ANT) Method to Reconstruct the Subsurface of Sumatra and West Java Using the New InaTEWS Seismic Network 15m Sumatra and West Java have a high potential for geological disasters, including volcanic eruptions and earthquakes. In the last two years BMKG has significantly increased the number of seismic stations in this area, by utilizing seismic waveforms recorded by the BMKG seismograph network of earthquake monitoring stations spread across the Sumatra (110 stations) and West Java (48 stations) for 5 months using the ANT method. The dispersion curve shows the subsurface information that can be imaged from a period of 1 to 50 seconds. We use subspace inversion to test the resolution to get the best parameters for inversion. Based on the results of the resolution test, subspace inversion will use a grid parameter of 100 x 100 km, and smoothing and dumping of 500 each. The resulting group velocity mapping information also corresponds to the geological information and Bouguer anomalies. To generate subsurface information in Vs against depth we use the Neighborhood Algorithm (NA) method. The subsurface information generated shows excellent results on a regional scale. Large faults that are scattered throughout Sumatra and West Java, the dimensions of the faults, as well as the existence of the basin in the western part of Sumatra can be well imaged. Speaker: Mr Agustya Adi Martha (Indonesian Agency for Meteorology, Climatology and Geophysics (BMKG), Jakarta, Indonesia) • 11:45 Analysis of foreshock sequences in the Iranian plateau 15m We analyze foreshock activity in the Iranian plateau by investigating the occurrence patterns for isolated M >= 5.5 earthquakes from 1968 to 2018. Among the 165 mainshocks with M >= 5.5 (after excluding 12 aftershocks, 6 swarms and 9 doublets), 18 percent are preceded by at least one foreshock within 30 days and 20 km. However, the number of events in each foreshock sequence is significantly higher in the last ten years of the catalog. This difference is partly explained by the rapid expansion of the Iranian national seismographic network in the recent years. Based on our analysis, the completeness magnitude of the catalog is declined over years and reached to 3.4 (2008-2018) from 5.1 (1968-1998). Foreshock occurrence appears correlated with mainshock faulting type and depth; however, it is not correlated with mainshock magnitude. These results suggest that foreshock occurrence is largely controlled by the regional tectonic stress field and fault zone properties. In special cases, foreshock activity is considered as one of the most promising precursory changes for the main shock prediction in the short term; however, foreshock properties are not reliably predictive of the magnitude of the eventual mainshock. Speaker: Ms Mania Sabouri (Engineering Seismology, IIEES, Montreal, Canada) • 11:45 Beni Illmane Earthquake Of May 14, 2010 - Aftershock Sequence Location Using A Dense Seismic Network 15m Algeria suffered frequently from effects of destructive moderate sized and strong earthquakes because of the seismotectonic setting on the boundary of African and Eurasian tectonic plates. On May 14th, 2010 at 13 h 29 m GMT, a moderate earthquake of magnitude Md 5.2 (CRAAG – Algeria) struck Beni-Illmane a village located about 200 km southeast of Algiers. The main shock caused substantial damage and resulted in three fatalities, 86injured, 1720out of shelter families and 6431 constructions damaged. The main shock was followed by a significant number of aftershocks for days after the earthquake. The Beni-Illmane earthquake sequence, which started on May 14th, 2010, occurred in a region of low to moderate seismic activities in north Algeria. Following the first main shock, the CGS – Algeria acted and organized a seismic survey of aftershocks using 13 temporary seismic stations installed close to the epicentral area during 30 days recording period. The data were analyzed performing single events location, relocated using MJHD method and calculated composite focal mechanism solution. The results obtained showed a distribution of aftershocks in two clusters oriented NNE-SSW and east-west. The composite focal mechanism showed a strike slip fault consistent with the global CMT solution. Speaker: Mr Moad Chikh (Centre National de Recherche Appliquee en Genie Parasismique (CGS), Algiers, Algeria) • 11:45 Development of Local Magnitude Scale and Determination of Station Magnitude Corrections for Northern Thailand 15m In this research, a local earthquake magnitude formula (ML and MLv) was developed for measuring earthquake magnitude in northern Thailand and determined station magnitude corrections. By using data from 31 seismic stations of the Earthquake Observation Division, the Thai Meteorological Department and CTBTO Chiang Mai seismic station, analyzed 148 earthquake events from 2009 to 2019 to find the formula. The magnitude ML was defined as ML = log A+ 0.6682 log(R/100)+ 0.0026(R-100)+ 3 and the magnitude MLv was defined as MLv = log A + 0.6002 log (R/100) + 0.0030(R-100) + 3, for hypocentral distance 25 to 500 km and depth below 60 km. The results comparing Richter’s local magnitude equation (1935) and the equation obtained from the study, found that the attenuation of earthquake magnitude in northern Thailand and southern California is quite similar. And the station magnitude corrections were between -1.1752 to 0.5393 magnitude. Speaker: Mr Tanongsak Taothong (Thai Meteorological Department, Bangkok, Thailand) • 11:45 Effect of soft soil on frequency content of waveform and its application on seismic site selection 15m Soft soil effectively changes the behaviour of seismic wave propagation and this is important for urban areas. Waveform modelling is one of the methods we can go through site effect and check how the underlying structure could amplify incoming waveform and how will affect low and high rise buildings. In this study, we have monitored a situation with and without soft soil on some existing stations and have tried to explore how much the amplification factor could change. A hybrid technique of waveform simulation is used to create near broadband signals. The method combines numerical (Finite Difference) and analytical (Modal Summation) techniques. A major earthquake (Bam, 2003) southern Iran is selected. Vp, Vs, rigidity and attenuation factors (Qp, Qs) are considered as soil condition at each site. 1D, 2D and 3D evaluation are performed to evaluate the detail effects of real source, path and site conditions. This procedure is a complementary technique to deliver clear site condition for any seismic site selection as well. Results are compared with observed data both in time and frequency domain. Speaker: Mr Vahid Gholami (Geopersian Company, Iran) • 11:45 Estimation of Mantle Transition Zone seismic discontinuities beneath northwestern South America from P-wave Receiver Function Analysis 15m The present work seeks to study the seismic upper mantle discontinuities of the northwestern part of South America and report the results of the first P-to-S radial receiver function investigation of the 410 km and 660 km depth discontinuities that bound the mantle transition zone (MTZ) beneath Colombia. In order to calculate the receiver functions and generate a first-order approximation of these discontinuities’ lateral depth variation and MTZ thickness. We used teleseismic information recorded in the broadband seismological stations of the National Seismological Network of Colombia between 1995 and the present year with epicentral distances in a range of 30 and 130 degrees and a magnitude greater than 6. Determining the extent of these seismic discontinuities features is the key to address several problems in region tectonics related to the structure, evolution, and mantle dynamics and study how is the behavior of the subduction processes of the Nazca and Caribbean plates beneath the South American plate. Speaker: Mr Jorge Enrique Cubillos Gordillo (Universidad Nacional de Colombia, Bogota, Colombia) • 11:45 How reservoir loading could change the seismic behavior and how should be managed? 15m Effects of reservoir filling are studied well during past decades by increasing monitoring stations around dams. In this study, a period of more than 10 years of seismicity around Seymareh dam (a major dam Southwestern Iran) is monitored and thousands of minor earthquakes around the lake is processed and evaluated before and after reservoir filling. Various parameters of active locations and faults, depth of events, magnitude, seismicity parameters (a-value, b-value) and source migration is explored in detail. It has been shown how lots of very shallow events are imposed on the area and how it affects by water level variations. An optimum rate for water level change is detected to minimize the induced seismicity effectively. Speaker: Mr Vahid Gholami (Geopersian Company, Iran) • 11:45 Investigating seismic radial anisotropy beneath the Zagros belt 15m In this research, the difference between the velocity of Rayleigh and Love waves is used to determine radial anisotropy beneath the Zagros belt. The continuous ambient noise data are processed to image 2D tomographic dispersion maps from the period of 8 to 50 s. Then, a quasi-3D shear wave velocity and radial anisotropy model are calculated by joint inversion of the Rayleigh and Love local phase velocity dispersion curves using MCMC method. Our results imply the presence of intense radial anisotropy due to the dense minerals in the crust and uppermost mantle of the Zagros zone. Radial anisotropy changes from positive values in the crust to negative values in the upper mantle which may be evidence for the decoupling of the crust from the upper mantle beneath the Zagros. Speaker: Mr Ramin Movaghari (International Institute of Earthquake Engineering and Seismology (IIEES), Tehran, Iran) • 11:45 Modern Seismological Network of Nepal 15m Nepal is exposed to intense seismic activity, including devastating earthquakes. The National Earthquake Monitoring and Research Centre (NEMRC) was established under the Department of Mines and Geology (DMG) to monitor those earthquakes. It also alerts the Nepalese authorities and population about the location and magnitude of the felt earthquakes to support rescue and relief operations at the earliest. The seismological network was deployed in collaboration with the Department of Analyse, Surveillance, Environment (DASE), France, and extended to a national network covering the whole territory since 1994. 21 short period stations were tele-operated at two seismic centres, a network updated to digital between 2014 and 2016. NEMRC provides some seismic bulletins to international institutes and became the NDC of Nepal for CTBTO. The Gorkha earthquake (Mw 7.9) happened on 2015 April 25 under the network's central part. The number of stations were then increased with several international organizations (including Chinese and Japanese institutes). It now reaches a total of 41 broadband and short period instruments. These stations, exposed to low seismic noise levels, recorded more than 100,000 earthquakes, including more than 50,000 events following the Gorkha earthquake. The modern network allows improving the quality of the catalogue useful for seismological research. Speaker: Mr Lok Bijaya Adhikari (National Seismological Centre, Department of Mines and Geology, Kathmandu, Nepal) • 11:45 National network data contributions to seismic studies in the Kingdom of Saudi Arabia 15m Increased urban development, occasional volcanic swarms, and large earthquakes surrounding the Kingdom of Saudi Arabia (KSA) have contributed to a renewed interest in understanding seismic hazard and risk within the Kingdom. In response, the KSA has expanded the national seismic network over the past several decades. Now, a sizable collection of local and regional data provides an opportunity to further develop KSA capabilities in seismology and seismic hazard assessment. The Lawrence Livermore National Laboratory (LLNL) and the National Center for Earthquakes and Volcanoes (NCEV) of the Saudi Geological Survey (SGS) started collaborating in 2016, with long-term goals of reducing seismic hazard and risk. We began by using time-domain full waveform moment tensor inversion and coda-envelope derived amplitude measurements to solve for earthquake source mechanism, moment magnitudes, and their source-type. We compare the moment magnitudes calculated from the two methods and publicly available earthquake catalogs and discuss the implications of the obtained source parameters. This study supports NCEV operational needs while obtaining stable and robust solutions that give quantitative information about the seismicity needed to better understand potential seismic hazards. A parallel collaborative study is focused on improving attenuation models of lithosphere for a broad frequency band using multiple-phase inversion. Speaker: Ms Rengin Gok (Lawrence Livermore National Laboratory (LLNL), Livermore, CA, USA) • 11:45 Occurrence And Extent of Earth Fissures: Preliminary Findings From Chikwawa District, Southern Malawi 15m Although earth fissures have occurred in some parts of the country, they have not been well-documented or studied in detail. Recent field investigation into the formation and extent of earth fissures in Chikwawa District, reveal their formation due to erosion as well as tensional cracks within the affected area as a result of groundwater withdrawal from the alluvial sediments. Several sinkholes and linear fissures trending N-S and E-W, connected by horizontal conduits characterized by mud deposition and mud flow, cut through the village thereby weakening and cracking houses. Minor fissures connect orthogonally to major fissures without clear offsets. The water flow through the conduits influenced the formation of sinkholes and conduits by weakening their structural strength which caused top soil to collapse into existing voids, creating or widening the sinkholes and exposing the conduits. We used geological, airborne geophysical as well as seismic ambient noise to delineate structures and determine depth-to-bedrock. Additionally, data from local as well as international seismological monitoring networks indicate no occurrence of an earthquake in the vicinity to attribute such activity to tectonic movement or faulting. Speaker: Mr Patrick Rafiki N. Chindandali (Geological Survey of Malawi, Malawi) • 11:45 Probabilistic Seismic Hazard Map for Bolivia (PSHBO) 15m On this research we present a probabilistic seismic hazard map for Bolivia (PSHBO-2019), this is the first map that integrated all variables available within the geo hazard for our country. We propose 13 seismic zones based on epicentral distribution, stresses and geology context, we applied the well know method for hazards assessment integration to all variables to have the maximum probable acceleration for each zone. Our results include a return period of 475 and 2475 years with five structural periods that let us to build the uniform hazard spectrum for our country. The crustal earthquakes located at along the Eastern Cordillera, Inter Andes and part of the Sub Andes (known as Bolivian Boomerang) present peak ground accelerations up to 24% of gravity, for the subduction earthquakes show almost 34% of gravity those are located at Western Cordillera, for Altiplano the peak ground accelerations reach up to 16%, for Chaco and Beni plains accelerations of 4% of gravity. Speaker: Mr Gonzalo Antonio Fernandez (Observatorio San Calixto, La Paz, Bolivia) • 11:45 Regional tectonic activity and its impact on increasing level earthquakes in Iraq 15m Iraq is a country subject to seismic activity associated in a belt Zagros-Taurus which is caused by the collision of the Arab plate with the Eurasian plate. Where the Arab plate is affected by three types of tectonic boundaries: divergent boundaries, convergent boundaries, seam boundaries. The Arab plate moves north-east, leading to the expansion of the area of the Red Sea and the Gulf of Aden on one hand and increasing the collision at the mountains of Makran, Zagros and Taurus on the other hand. We note this motion from time to time being represented by light, medium and strong earthquakes. The Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) provides the Member States, by the requirements of the verification regime, the data from seismological monitoring stations, one of the four techniques used by the organization to achieve its goals of making the world free from Nuclear weapons and supporting the scientific and practical side concerned with the monitoring of earthquakes and their effects. In this poster the level of seismic activity witnessed in Iraq from 2017 to 2018 and defining mb, Ml to determine Mw which was signal of increasing seismic activity is shown. Speaker: Mr Saif Kadhim Gatea Al-Behadili (Iraqi National Monitoring Authority, Iraq) • 11:45 Seismic Hazard Estimates for State of Uttarakhand Himalaya in terms of Peak Ground Acceleration (PGA) 15m Probabilistic Seismic Hazard Assessment (PSHA) for the state of Uttarakhand (280-320 N and 770-810 E) has been investigated considering two Next Generation Attenuation (NGA) models. Results are presented in terms of PGA for various return periods for each district. Initially, based on seismicity and seismtectonic characteristics the whole region has been defined into four seimogenic zones (UK-I, UK-II, UK-III and UK-IV. Seismic hazard computation is performed using CRISIS 2015. The study area has been divided into grid size of 0.2° x 0.2°. The input parameters are seismicity parameters and attenuation models. The estimated seismicity parameters and (NGA) models have been used to produced seismic hazard in terms of PGA for 20%, 10% and 2% probability of exceedance in 50 years which are equivalent to return periods of 225, 475 and 2475 years respectively. The hazard Contour maps have been produced for mean PGA for 2%, 10% and 20% probability of exceedance in 50 years as well as Uniform hazard spectra (UHS) at various sites for return periods of 225, 475 and 2475 years have been plotted and the rate of occurrence of earthquakes and PGA are compared in each source zone. Speaker: Mr Daya Shanker (Indian Institute of Technology, Roorkee, India) • 11:45 Seismic Microzonation of DKI Jakarta Indonesia Using HVSR Method 15m Earthquake disaster mitigation is required to perform in DKI Jakarta which is the Capital of the State of Indonesia. To find out the geological characteristics of the study area such as soil type and rock type, an HVSR analysis was performed. The amplification value and dominant frequency can be used to estimate the level of building damage due to earthquake, damage to buildings due to the earthquake will be more severe in areas that have HVSR parameters with high amplification values and low-frequency values. We compared the amplification value between 30 temporarily installed seismic stations and one of the CTBTO seismic stations, LEM which is in the south of the study area. The LEM is in the bedrock so that it can be used as a reference to determine the amplification in this region. Based on the analysis that has been done by correlating the results of zoning maps from amplification, dominant frequency and soil vulnerability index, it is known that the area with high level of damage if an earthquake occurs is the area around Ancol in North Jakarta which is a coastal area and near the swamp. Speaker: Mr Bayu Pranata (Indonesian Agency for Meteorology, Climatology and Geophysics (BMKG), Jakarta, Indonesia) • 11:45 Shear wave velocity structure of upper mantle along the Zagros collision zone 15m Investigation of the lithospheric shear-wave velocity as a clue helps to improve our understanding of Iranian plateau evolution. Therefore, we estimate shear wave velocity models beneath profiles perpendicular to the Zagros strike by using trans-dimensional Bayesian inversion of the Rayleigh wave group velocity dispersions at periods of 5-120 s. Our velocity models, in line with the support of the segmented slab, show that the different geodynamic processes have dominated in the northern and central-southern Zagros. In the northern Zagros, the Arabian lithosphere, near the suture, has likely experienced distributed thickening while it has underthrusted beneath central Iran in the central-southern Zagros. The presence of a high-velocity anomaly at depths 80-120 Km elongated between the low-velocity lithospheres of the UDAM and the Lut block implies that the southern slab has not flatted up to the east of Iran and the Eocene-Oligocene flare-up magmatism in the Lut block is directly independent on the Neo-Tethys subduction. Our results support the slab break-off idea along the Zagros. In the central and southern Zagros, lateral tearing might be responsible for the slab detachment so that has started from beneath the central UDMA. Speaker: Mr Habib Rahimi (Institute of Geophysics, University of Tehran, Tehran, Iran) • 11:45 Statistical assessment of seismicity level of the central part of the Baikal rift zone 15m The seismicity change in time in the seismically active region around the central part of the Baikal rift zone (BRZ), the South-East of Russia, was investigated using the statistical estimate of the seismicity level (SESL’09) procedure [Saltykov, 2011]. The method is based on calculating the statistical distribution function of the decimal logarithm of the total seismic energy within a given spatial object in a certain time interval. Epicenter data taken from the International Seismological Centre [http://www.isc.ac.uk/iscbulletin/search/catalogue] and from the local catalogue from 1962 to 2019, which includes over 3.5 thousand earthquakes with an energy class equal to or higher than 8.5, were analyzed. This concept enables us to formed and defined "seismic background" for considered region. And allows us to conduct the further assessment and comparison with the seismic regimes of the other areas. The work has supported by the Ministry of science and higher education of the Russian Federation (within the framework of state task No. 075-01304-20 and the research project IX.136.1., state number AAAA-A16-116121550016-3) and using data obtained at the unique scientific installation "Seismic and Infrasound monitoring complex of the Arctic cryolithozone and continuous seismic monitoring complex of the Russian Federation, neighboring territories and the world". Speaker: Ms Larisa Tcydypova (Geological Institute of the Siberian Branch of the Russian Academy of Sciences (GIN SB RAS), Russian Federation) • 11:45 The use of Seismological, Geodetic and Infrasound techniques for novel integrated monitoring scheme in Nigeria 15m Nigeria lies within the West African sub-region and the country is believed to be aseismic in nature. Despite this view by prominent geoscientists, the country has witnessed both historical and instrumental earthquakes since 1933. The recent recorded chains of events with moment magnitudes ranging from 3.0 to 3.4 in Nigeria, were located in Kaduna state and Abuja. Reasons which include shallow faults reactivation by hydraulic fracturing, anthropogenic causes, etc., have been adduced to the recurrent earth tremors in Nigeria. As the events are of small to medium magnitudes, their vibrations felt in different parts of the country were not recorded by the scanty existing seismic stations. This paper therefore, presents a novel integrated approach towards understanding Nigeria’s seismicity, and enhanced monitoring of seismic hazard through improved recording capability of earthquakes. It outlines a detailed scheme on densification of seismographs collocated with GPS, and deployment of the advanced Infrasound equipment to strategic areas where earth vibrations are frequently observed in Nigeria but not recorded by seismic equipment, etc. The realization of the monitoring scheme would not only assist Nigeria in seismic risk mitigation and holistic planning, but will promote collaboration with the CTBTO and other key partners. Speaker: Mr Umar Afegbua Kadiri (Ministry of Science and Technology, Abuja, Nigeria) • 11:45 United Arab Emirates Strong Motion Network 15m UAE strong motion network consists of 62 stations distributed all over the country to construct UAE-Ground GSM “ShakeMaps” for existing urban areas and areas under strategic development. Additionally, structural design parameters will become available for verification and calibration of the seismic design code. Forty stations are equipped with shallow borehole EpiSensors and fourteen stations with surface EpiSensors installed on open ground or in small buildings and 7 stations equipped with TSA-100 and one station equipped with Titan. Stations use high dynamic range, IP aware, digitizer model Basalt, Trident or Quanterra, for data acquisition. The network telemetry topology consists of wireless GPRS backbone with data service from multiple ISPs and some station transmit data via VSAT. A site characterization study at each site included geotechnical and geophysical analyses, microtremor testing, and soil dynamic investigations. The integral results provides estimation on the potential effects of local site conditions upon recorded ground motions. The primary operational objective is to provide input accelerations in real-time for the automatic calculation and distribution of reliable UAE-GSM “ShakeMap” immediately after a seismic event. Speaker: Mohamed Al Afeefi (National Center of Meteorology, Abu Dhabi, United Arab Emirates) • 11:45 Updates to the Regional Seismic Travel Time (RSTT) tomography model: tomography and path-dependent uncertainty 15m A function of global monitoring of nuclear explosions is the development of Earth models for predicting seismic travel times for more accurate calculation of event locations. Most monitoring agencies rely on fast, distance-dependent one-dimensional (1D) Earth models to calculate seismic event locations quickly and in near real-time. RSTT (Regional Seismic Travel Time) is a seismic velocity model and computer software package that captures the major effects of three-dimensional crust and upper mantle structure on regional seismic travel times, while still allowing for fast prediction speed (milliseconds). We describe published updates to the RSTT model (pdu202001Du, https://www.sandia.gov/rstt) using a refined data set of regional phases (i.e., Pn, Pg, Sn, Lg). We improve on the former distance-dependent uncertainty parameterization for RSTT using a random effects model to estimate slowness uncertainty as a mean squared error for each model parameter. The random effects model separates the error between observed slowness and model predicted slowness into bias and random components. Validation of the updated RSTT model demonstrates significant reduction in median epicenter mislocation along with more appropriate error ellipses, compared to the iasp91 1D model as well as to the current station correction approach used at the Comprehensive Nuclear-Test-Ban Treaty Organization International Data Centre. Speaker: Mr Michael L. Begnaud (Los Alamos National Laboratory (LANL), Los Alamos, NM, USA) • 11:45 Updating seismic hazard models for Kuwait 15m This research assesses the seismic hazard and deaggregation in the State of Kuwait. For this purpose, the historical and instrumental seismic catalogues of Kuwait and the active Zagros Seismic Belt were compiled, unifying the magnitudes, removing unnecessary earthquakes (seismicity declustering) and considering the completeness of the catalogues. Multi-seismotectonic models for the Kuwait region incorporate earthquake focal mechanisms, seismicity patterns, and the structural geological situation have been created to reduce epistemic uncertainty. The recurrence parameters as well as the maximum expected earthquake from each seismic source were fundamentally estimated. Appropriate ground motion attenuation relation within a logic tree formulation was mainly used in creating hazard maps. A state-of-the-art probabilistic approach is used herein to produce hazard maps at return periods of 75, 475, 975 and 2475 years (equivalent to 50%, 10%, 5% and 2%, respectively, probability of exceedance in 50 years) at periods of PGA, 0.1, 1 and 4 seconds. The computations of hazard maps were constructed using a spacing grid of 0.2° × 0.2° in the Kuwait area. Uniform hazard spectrum and deaggregation charts have been adopted for all six governorates of Kuwait. Speaker: Mr Abdelaziz Khairy (Kuwait institute for Scientific Research (KISR), Kuwait) • 11:45 Upper crustal structure at the KTB drilling site from ambient noise tomography 15m In this study, we show results from ambient noise tomography at the KTB drilling site, Germany. The Continental Deep Drilling Project, or ‘Kontinentales Tiefbohrprogramm der Bundesrepublik Deutschland’ (KTB) is at the northwestern edge of the Bohemian Massif and is located on the Variscan belt of Europe. During the KTB project crustal rocks have been drilled down to 9 km depth and several active seismic studies have been performed in the surrounding. The KTB area therefore presents an ideal test area for testing and verifying the potential resolution of passive seismic techniques. The aim of this study is to present a new shear-wave velocity model of the area while comparing the results to the previous velocity models. We use a unique data set composed of two years of continuous data recorded at nine 3-component temporary stations installed from July 2012 to July 2014 located on top and vicinity of the drilling site. Moreover, we included a number of permanent stations in the region in order to improve the path coverage and density. We present here a new velocity model of the upper crust of the area, which shows velocity variations at short scales that correlate well with geology in the region. Speaker: Mr Ehsan Qorbani (CTBTO Preparatory Commission, Vienna, Austria) • 09:00 12:00 T1.3 e-poster session: T1.3 - The Oceans and their Properties T1.3 Conveners: Mr Georgios Haralabus (CTBTO Preparatory Commission, Vienna, Austria) , Peter Louring Nielsen (CTBTO Preparatory Commission, Vienna, Austria) • 09:00 12:00 T1.3 e-poster session: e-poster session - T1.3 - The Oceans and their Properties Online #### Online T1.3 Conveners: Mr Georgios Haralabus (CTBTO Preparatory Commission, Vienna, Austria) , Mr Peter Louring Nielsen (CTBTO Preparatory Commission, Vienna, Austria) • 09:00 A self-consistent estimate of the CTBT IMS hydrophone locations using scientific airgun data from the CEVICHE trial (Chile) 15m The CTBT IMS hydroacoustic sensor network composed of 6 hydrophone stations and 5 T-phase is part of the global CTBT verification regime. The hydrophone stations consist of hydrophone triplets. Each hydrophone is suspended in the ocean at a depth close to the SOFAR channel axis and anchored by a riser cable to the ocean floor. The geometry of the triplets and dedicated data processing allow for estimating the direction of arrival (or back-azimuth) of an incoming signal used for localizing the event. An accurate deployment position of each hydrophone in the triplet is essential to obtain an accurate location of an event by back-azimuth estimation that may originate thousands of kilometers from the triplet. CTBTO has in the past developed an algorithm calculating re-location of hydrophones based on numerous analyst reviewed event locations obtained by the entire CTBT IMS sensor network. In this study, the algorithm is applied to the HA03 hydrophone station to estimate possible corrections to the hydrophone locations. The Progressive Multi-Channel Correlator algorithm is updated with the hydrophone re-location, and a series of signals from a scientific airgun survey recorded during the CEVICHE trial (Chile) demonstrates the improvement in back-azimuth estimates by the hydrophone re-location. Speaker: Mr Peter Louring Nielsen (CTBTO Preparatory Commission, Vienna, Austria) • 09:15 Global hydroacoustic simulations on high-performance computers 15m The Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) is operating and maintaining the international monitoring system of seismic, infrasound, hydroacoustic and airborne radionuclide facilities to detect a nuclear explosion over the globe. The monitoring network of CTBTO, especially with regard to infrasound and hydroacoustic, is quite unique because the network covers the globe, and the data is open to scientific use. On the other hand, global scale computer modelling of acoustic signal transmission has not been well established. In this presentation, improvements on such global acoustic transmission models will be presented with particular focus on high-performance computing. Speaker: Mr Noriyuki Kushida (CTBTO Preparatory Commission, Vienna, Austria) • 09:30 Modeling of hydroacoustic propagation based on the normal mode-parabolic equation method 15m Abstract: In view of the low accuracy of the far-field modeling of underwater explosion sound propagation, the normal mode-parabolic equation method is used to carry out the modeling of hydroacoustic propagation to optimize the ability of far-field propagation simulation. This method combines the advantages of the normal mode model method and the parabolic equation method, adopts local normal mode analysis in the vertical direction, and uses the parabolic equation method to solve the normal mode amplitude equation in the horizontal direction. This method can be used to simulate the sound propagation loss of underwater explosions, and combined with the sound velocity profile, the theoretical travel time of sound propagation can be calculated. This method solves the problem that the high frequency situation is hard to calculate with the parabolic equation method, and the algorithm is able to extended to three-dimensional simulation. Speaker: Mr De Nan (CTBT Beijing National Data Center, Beijing, China) • 09:45 Remote detection of hydroacoustic signals potentially associated with the sinking of SS El Faro using CTBT IMS hydrophone data 15m On 1 October 2015, the cargo ship SS El Faro was lost approximately 120 km east of Long Island, The Bahamas, during the Hurricane Joaquin. Here, we analyze underwater sound phases potentially associated with the loss of this vessel, recorded by station HA10 of the Comprehensive Nuclear-Test-Ban Treaty (CTBT) International Monitoring System (IMS) located at Ascension Island, Mid-Atlantic Ocean. Results from progressive multi-channel correlation and spectral analysis of broadband arrivals at both hydrophone triplets of HA10 suggest that at least one impulsive, in-water event occurred within minutes after communication with SS El Faro had ceased and emergency buoys were activated. The derived event origin notably coincides with the confirmed location of the wreckage on the seafloor. Our findings are consistent with results from 2D transmission loss modeling and further highlight the exceptional capabilities of the IMS hydroacoustic network for detecting both natural and non-natural events in the global ocean. Speaker: Mr Dirk Metz (Japan Agency for Marine-Earth Science and Technology, Yokosuka, Kanagawa, Japan) • 10:00 Capability of the IMS hydrophone stations network to characterize low level underwater seismicity, underwater volcanism and iceberg events 15m The hydroacoustic component of the IMS network consists of a series of five island-based seismic stations and six cabled hydrophone installations located in the Indian, Pacific and Atlantic Oceans. In this study, we focus only on hydrophone stations, which provide low back ground high quality data: each one of these stations hosts a set of three hydrophones deployed at a depth of the SOFAR channel, as a small-aperture (~2 km) horizontal triangular array. The direction of arrival and the apparent velocities of broadband acoustic arrivals can be determined from array processing based on correlation or beam forming techniques, therefore enhancing the detection and location capabilities of such a sparse network. Several years of data are processed with DTK-PMCC detector and global association is performed to build automatic events. The precision of estimated wavefront parameters allows to image with an unexpected accuracy the spatial locations of active seismic areas associated to ridge, subduction and volcanic seismicity, for which propagation paths are not blocked by bathymetric structures. Antarctica iceberg events are also clearly detected with season-dependent locations. Obtained seismic events are compared to LEB events, and differences are discussed in terms of location accuracy, source energy level and ground-to-water coupling. Speaker: Julien Vergoz (Commissariat à l’énergie atomique et aux énergies alternatives (CEA), France) • 10:15 Recording of T-phases from the M7.4 Kermadec Trench earthquake in 2020 at the CTBT IMS HA03 hydrophone station 15m On 18 June 2020, energetic underwater acoustic T-phase signals were recorded at the Comprehensive Nuclear-Test-Ban Treaty (CTBT) International Monitoring System (IMS) hydrophone station HA03, located at the Juan Fernandez Islands, Chile. In this work, we investigate the origin of these T-phases, which were associated to an M7.4 submarine earthquake with epicenter in the Kermadec Trench located at a distance of approximately 8700 km from HA03. Analysis of the recorded T-phases was performed using the Progressive Multi-Channel Correlation algorithm (DTKGPMCC) installed on the CTBTO virtual Data Exploitation Centre (vDEC). This analysis revealed a strong signal correlation between North and South HA03 hydrophone arrays, different arrivals were identified within the duration of the earthquake, and the estimated back azimuth showed variability over time. The back azimuth results suggest that T-phases could be triggered at different locations along the Trench and far from the declared earthquake epicenter. Underwater acoustic signal travel times were estimated along different propagation paths by a Normal Mode model with realistic environmental input, and possible horizontally reflected and diffracted paths were calculated by a 3D Parabolic Equation model. Future research directions for the improvement of localization T-phase excitation from submarine earthquakes will be discussed. Speaker: Mr Tiago Oliveira (University of Aveiro, Portugal) • 10:30 Anthropogenic ocean noise: Mediterranean gateways versus open oceans 15m 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 IMS monitoring 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 increase by up to 20 dB at 40 Hz when compared to the open oceans. Speaker: Mr Ingo Grevemeyer (GEOMAR Helmholtz Centre for Ocean Research, Kiel, Germany) • 10:45 A theoretical formulation of a 3D acoustic propagation model for stratified oceanic media based on an indirect BEM approach. 15m Despite the progress made both in hardware and numerical techniques, 3D acoustic propagation for stratified oceans in cartesian coordinates, is still a challenge. In 2019, an approach to this problem restricted to short-range distances, using the Boundary Element Method (BEM), was reported (Li et al. J. Comput. Phys. 392, (2019): 694-712.). The BEM is a widespread method that exhibits certain useful advantages for solving time-harmonic scattering problems such as the fact that only integration in 2D boundaries is required, the Sommerfeld radiation condition is automatically satisfied, there is no need to add artificial absorbing layers and the seawater-seabed interface can be managed quite easily. The main disadvantage is that a non-homogenous medium like the oceanic environment must be modelled as a multi-domain problem which makes it computationally expensive and big enough to require using of iterative solvers as the Generalized Minimal Residual Method (GMRES) in addition to techniques for accelerating the evaluation of surface integrals. Here, an indirect BEM formulation, characterized by providing a more stable solution than the direct approach adopted in the previously mentioned work, which needs preconditioners to solve the involved linear system, is developed from its theoretical foundations through numerical evaluation of some representative benchmark situations. Speaker: Mr Juan D. Gonzalez (Argentinian Navy Research Office, Ministry of Defence, Buenos Aires, Argentina) • 11:00 IMS hydroacoustic hydrophone station detections associated with volcanic eruptions at Kadovar Island, Papua New Guinea 15m Following an eruption series at Kadovar Island, Papua New Guinea, the hydroacoustic datasets acquired by CTBT International Monitoring System (IMS) hydroacoustic (HA) hydrophone station HA11, Wake Island, were examined. HA11 is located approximately 3500 km northeast from Kadovar. Active eruptions restarted in January 2018 after a quiet period of three centuries. Cross-correlation analysis using two months of HA11 triplet data showed that the cumulative number of HA detections increased with time after commencement of the volcanic eruption series. According to local observations of Kadovar, a first eruption at the summit of the island was followed by four additional new vent spots and two vents were created near the shoreline. Our analysis suggests that the hydroacoustic signals detected by HA11 were associated with the volcanic eruptions near to the shoreline. A flank collapse resulting in erosion of the shoreline occurred on 9 February 2018. Hydroacoustic signals of long duration and small amplitude recorded at HA11 could be associated with this flank collapse. The present study demonstrates the potential contributions of the IMS HA stations data to the remote monitoring of underwater volcanic activity over large ocean areas. Speaker: Mr Hiroyuki Matsumoto (Japan Agency for Marine-Earth Science and Technology, Yokosuka, Kanagawa, Japan) • 11:15 An inverse problem approach for acoustic Transmission Loss estimation from the analysis of signals generated by seismic air-gun arrays. 15m Offshore seismic surveys with airgun array sources are currently widespread in all the oceans. They constitute one of the most powerful and systematic impulsive noise sources in marine environments. The sound pulses from large airgun arrays generate signals that contain sufficient energy in the 5-60 Hz band to propagate ocean-basin scales at ranges of hundreds to thousands of kilometres. Under favourable propagation conditions they can be received at the CTBT IMS hydroacoustic stations (HA) with high signal to noise ratio. Unlike previous work, our focus is neither to study their effects on marine species nor to investigate the stratified sedimentary structure of the seabed, but to evaluate whether these signals can be used to validate theoretical predictions of propagation models. A sample of recorded signals from seismic surveys obtained from the IMS HA historical data is exhaustively analysed through cepstral, spectral and time-based techniques. Then, based on the known characteristics of the energy source spectral density of airgun arrays below 100 Hz, as published in the literature, some underwater propagation properties are inferred. Speaker: Mr Igor Prario (Argentinian Navy Research Office, Ministry of Defence, Buenos Aires, Argentina) • 11:30 Modular nodes: Design and development of a novel mechanism which enables the repair of individual underwater components in IMS hydrophone stations 15m The six hydroacoustic hydrophone stations within the CTBTO’s International Monitoring System comprise a total of 11 triplets. These triplets have a 20-year design life with no scheduled underwater segment maintenance actions and are based on a linear non-modular design which offers the advantages of high reliability and efficient deployment in one continuous operation. However, a triplet employing modular components and Wet-Mate Connectors (WMC) has an advantage in that replacement of a failed component(s) in-situ becomes possible without disturbing the remaining functional system components, or requiring replacement of the entire triplet. For these reasons a modular design triplet that maintains the efficient deployment of a non-modular linear system has been investigated. A critical component that has been developed is a latch mechanism that secures the cable terminations to the node structure. This isolates the WMC plug and the cable from the deployment stress which they are otherwise unable to sustain. After deployment, the latch can be opened; should a repair then become necessary, detachment of the cable and termination can be undertaken by an ROV. The design principles, the status of fabrication and testing of the modular cable latch are presented, along with the envisaged development of a prototype. Speaker: Mr Mario Zampolli (CTBTO Preparatory Commission, Vienna, Austria) • 11:45 Acoustic Energy Propagation in the Ocean Along Areas of Strong 4-Dimensional Sound Speed Variability 15m The ocean is subject to complex dynamics that can produce time variant sound speed gradients with horizontal scales with potential to impact medium to high frequency acoustic propagation. Some of these features can critical grazing angles that may result in horizontal sound refraction, producing areas of stronger and weaker energy, time delays in the acoustic arrivals and changes on multi-path characteristics. The operational ocean forecast systems have skills to resolve some of these processes, but the acoustic propagation modeling solutions need to be able to handle these complex sound speed fields in order to reproduce the resulting sharp loss/gain changes along levels and directions (3D effects). These features can impact the accuracy of algorithms estimating source localization or doing ocean tomography and data assimilation. This work outlines a framework to diagnose when sound speed variability may be strong enough to trigger these 3-D effects following a risk management approach. It uses real-time ocean model forecasts, to build diagnostic variables estimating the possible acoustic impacts of ocean frontal systems and instabilities. The resulting analysis can be used to select numerical solution approaches and/or to create awareness regarding possible errors in the interpretation of acoustic signals in areas subject to strong dynamics. Speaker: Mr Emanuel Coelho (Applied Ocean Sciences, LLC) • 11:45 Could short duration broadband signals identified in IMS hydrophone recordings be Right Whale vocalizations? 15m The six CTBT IMS hydroacoustic hydrophone stations, comprising 11 triplets in total, record continuous data sampled at 250 Hz. Marine mammal vocalizations are frequently identified in these recordings and form an integral part of the HA stations’ undersea soundscapes, as reported in numerous scientific publications. During regular IMS hydrophone data quality checks, occasional short duration broadband signals occupying the entire available bandwidth were identified, which differ from the longer duration sweeps and chirps of whale calls reported in prior studies that made use of IMS hydrophone data. When such a sound appears on more than one hydrophone of a triplet, the recordings show amplitude variations across hydrophones that are indicative of a nearby source. Furthermore, the signals do not show signs of dispersion from long-distance propagation. The hypothesis is formulated that these sounds may be the low-frequency portion of short impulsive broadband vocalizations, referred to in the literature as Right Whale “gunshots”. Recordings of this endangered species are relatively rare compared to vocalizations from other whales and their study is receiving increased interest from the scientific community. Speaker: Mr Mario Zampolli (CTBTO Preparatory Commission, Vienna, Austria) • 11:45 Observed laterally reflected hydroacoustic signals generated by underwater impulsive sound sources 15m The International Monitoring System (IMS) of the CTBTO includes hydroacoustic stations composed of underwater hydrophones placed at the depth of the SOFAR channel. Since the hydroacoustic component of the network is designed to detect underwater nuclear explosions, events of special interest are impulsive underwater explosions. Among these, we studied several underwater explosions detonated close to the coast of Florida in September 2016 and 4 impulsive-like events (likely also underwater sources) from the Kamchatka area recorded in August 2020. In both cases, we observe secondary arrivals on IMS station HA11 for the Kamchatka sources and HA10 for the Florida sources immediately following the direct hydroacoustic arrivals. We assume these secondary arrivals are due to coastal reflections. We identify the potential reflection points for these reflections based on their back azimuths at the recording station and the estimated location of the impulsive sources. To verify this, we used the IDC standard hydroacoustic analysis tool HART and DTK-(G)PMCC, the latter provided to CTBTO authorized users, to estimate back azimuths. Comparisons between sources in the same general area give us an idea of the consistency of these reflections between sources in the same general area. Speaker: Ivana Jukic (CTBTO Preparatory Commission, Vienna, Austria) • 09:00 12:00 T5.3 e-poster session: T5.3 - Capacity Building, Education, Communication and Public Awareness T5.3 Conveners: Mr Gerard Rambolamanana (CTBTO Preparatory Commission, Vienna, Austria) , Ms Misrak Fisseha (CTBTO Preparatory Commission, Vienna, Austria) • 09:00 12:00 T5.3 e-poster session: e-poster session - T5.3 - Capacity Building, Education, Communication and Public Awareness Online #### Online T5.3 Conveners: Mr Gerard Rambolamanana (CTBTO Preparatory Commission, Vienna, Austria) , Ms Misrak Fisseha (CTBTO Preparatory Commission, Vienna, Austria) • 09:00 Building effective awareness networks in XXI Century. 15m The CTBTO mission has been linked since the beginning of the Treaty to cooperation models between diverse stakeholders in science, technology and policies areas in order to make its task more effective and comprehensive. Nevertheless, there is still a long way to go in this regard and many actors must be incorporated on the effort to build a real awareness, to ensure joint initiatives can be spread out as far as possible and achieve the deepest penetration, both in general public as well as at all political levels - the decision makers on this matter. Several NGOs could contribute weaving a massive network to spread out related issues. The aims of this work are about how alliances built between some sectors related to CTBTO initiatives, through resources such as training, media communication and lessons learned from areas of similar complexity, could optimize the communication about disarmament and non-proliferation issues. This could become relevant topics of discussion that encompass the whole of society. Speaker: Ms Mariana Elizabeth Gordillo (Autoridad Regulatoria Nuclear, Buenos Aires, Argentina) • 09:15 Improvements of data analysis and capacity building by NDC - Costa Rica using IMS stations and advances in updating NDC-in-box programs 15m In recent years with the installation of the NDC-Costa Rica since 2010, improvements have been made in advances in data analysis by CTBTO tools to the states party of the treaty. On the part of the NDC-Costa Rica, the real-time inclusion of IMS seismic stations and OVSICORI local seismic stations for monitoring local, regional, global seismic and infrasonic events automatically through SeisComp 3 acquisition system included in the NDC-in-a box. With the different trainings by CTBTO, some analysis of events data has been carried out, such as: explosion in the Port of Beirut (2020-08-04 15:08 UTC) where IMS stations were used: I26DE, I42PT, I11CV, I17CI, I48TN (infrasound), BRTR, IDI, ASF, EIL, MMAI (seismic) and Stromboli Volcano eruption event in Italy (2019-07-03 14:45 UTC) through infrasound stations: I26DE, I37NO, I42PT, I48TN. In addition, in recent years all data analysis programs such as Geotool, DTK-GPMCC, DIVA, Webgrape, SeisComP 3 have been updated to be accessible to NDC-Costa Rica users for data analysis. Speaker: Mr Hairo Villalobos (Observatorio Vulcanologico y Sismologico de Costa Rica (OVSICORI), Costa Rica) • 09:30 Communication and Public Awareness 15m This presentation will examine the extensive efforts of the CTBTO Technical Secretariat to advance public awareness of the Treaty, and will explore what NGOs have done to further this effort. Most important, it will investigate the avenues that academics, NGOs, and scientific experts can pursue, in particular in cooperation with each other and with respective governments. The CTBTO has established an impressive Group of Eminent Persons and Youth Group; outside, in civilian society, more must be done. Academics, NGOs, and scientific groups can pursue through Coalitions (such as one formed by this author) educational panels, workshops, speaking engagements, at meetings and major international conferences. Their efforts can help exert pressure on governments to ratify the treaty. For example, a U.S.-China symposium organized by specialized, highly recognized thinktanks, NGOs and academics in both countries, would attract considerable attention and could find a receptive audience among government policymakers regarding the reasons for ratification. Although ratification in the U.S. depends on the U.S. Senate, the Biden Administration likely will have a more positive view of the CTBT than the previous administration. Also, while the G7 has supported entry into force of the CTBT, the Treaty is not expected to be a central point of discussion at the NPT Review Conference as it used to be. Speaker: Ms Jenifer Mackby (Federation of American Scientists (FAS), USA) • 09:45 Nuclear Education and Training of Young Professionals with CTBTO Content. 15m Education and training of young professionals in the nuclear industry are one of the Nuclear University primary objectives. In achieving this goal, it is vital that attention must be paid to all aspects of the development and use of nuclear power and nuclear technology. Future generations must understand and share the responsibility for the stability and safety of our entire world. CTBTO has made great efforts to ban all nuclear weapon tests. This is a crucial issue and this work definitely makes our world safer and our life more secure. The significance of education and research activities in this field cannot be overstated. We started from the participation in the CTBT Public Policy Courses and then CTBT Science Diplomacy Symposiums and CTBT Science and Technology Conferences have led us to including of the CTBT-related topics in the student’s curriculum. It is very important that CTBTO offers excellent e-learning resources such as the CTBTO Knowledge and Training Portal (KTP) and CTBTO channel on iTunes. The survey shows grooving of the student’s interest to the CTBT and CTBTO educational resources. In addition, the majority of respondents said that they would like to take part in the CTBTO activities. Speaker: Mr Grigory Zinovyev (National Research Nuclear University MEPhI, Moscow, Russian Federation) • 10:00 Converging Knowledge and Technology Role on University’s Non-Proliferation Culture 15m University, indispensable for research, is one of the pillars of the prosperity and security of future generations. The diversification of research impose new ethical rigor hanging in the dissemination of the results. Responsible management of research in universities requires active commitments from relevant institutions. The progress in free access to information on the internet shows an increase role of security in scientific and innovative databases, especially of unclassified information for various reasons for dual use materials and technologies. Research is most vulnerable to unethical use because it generates and provides knowledge, materials, methods and technologies that could be channeled into crime or terrorism. However, scientific researchers and engineers play a key and responsible role in non-proliferation. Researchers are the most knowledgeable and best placed professionally to assess the nature and seriousness of the potential for misuse of knowledge, products or technologies. In this way, they should be the most responsible for evaluating and reporting on these findings within the research institution and to relevant national bodies. It is imperative to implement an optional discipline related to engineering and non-proliferation for students specializing in research. Such an alternative or optional course is currently under development at the mentioned technical university center. Speaker: Mr Artur Buzdugan (Technical University of Moldova, Chrisinau, Moldova) • 10:15 Summer School in old Nuclear Test site 15m Humanity may be destroyed by its very own progress of successfully harvesting or releasing atomic energy. For my country and for me personally, this is not a concern: Kazakhstan was the first country who joined and signed for NWFZ in 2008. Our country learned an important lesson from the tragedy of Semei. Nuclear weapons are not just short time weapons. They are long lasting guns, which will effect the environment for centuries. Kazakhstan tested around 456 nuclear bombs from 1949 until 1989. Most of them were tested close to the different villages to see the effects to humans, cattle and animal products, buildings and so on. This is only place where a population still lives in the territory of a nuclear test site. They are coping with extremely high rates of cancer and infant mortality. Furthermore, many mutilated children are born. It is very important to teach students the real facts related to nuclear test effects. The universities of Kazakhstan can teach unique courses on nuclear weapons and arms control, and visit the nuclear test sites and talk with the local people, study their cases and help them to overcome their fear and disease. Speaker: Mr Meirzhan Temirbayev (Eurasian National University, Nur-Sultan, Kazakhstan) • 10:30 Joint Seismic Monitoring Activities In Central Asia 15m Central Asia is tectonically complicated with high seismic activity. Over the past 150 years four great earthquakes occurred with magnitudes exceeding 8. Seismic monitoring is one of the most important problems of the region, having both scientific and social significance. Since many years, NORSAR (Norway), the Institute of Geophysical Research (Kazakhstan), and the Institute of Seismology (Kyrgyzstan) are cooperating to solve this problem. A joint scientific program is focusing on capacity building in Central Asia, in relation to technical verification of compliance with the CTBT, as well as research on improved seismic monitoring. Under this cooperation, seismic stations and the National Data Centres (NDC) in Kyrgyzstan and Kazakhstan were upgraded and Central Asian seismologists were trained at the Training Centre, established at Kazakhstan’s NDC. In 2018, joint work started on compiling a new seismic bulletin for Central Asia, based on data from 51 stations and 5 arrays. Observed magnitude and energy class discrepancies were studied with respect to systematic station and network effects. Aftershock sequences of 80 earthquakes with different magnitudes were analysed. The induced, anthropogenic and natural seismicity from different regions with mining activities in Kyrgyzstan and Kazakhstan as well as icequakes in the Tien Shan glaciers were analysed. Speaker: Mr Johannes Schweitzer (Norwegian Seismic Array (NORSAR), Kjeller, Norway) • 10:45 CTBT 2026: Scaling up Youth Initiatives 15m 2026 marks the 30th anniversary of the adoption of the CTBT and the establishment of the CTBTO. One of the most powerful tools that can help the CTBT enter into force is the young generation. We hope that the CTBT Youth Group could break this vicious circle. We are aiming to establish a project to raise awareness for the young generation and to educate them. We have already assembled a team of activists and arranged sessions of 30-minute interactive seminars with NRNU MEPhI pre-university students. The target is to explain technical terms in simple words, plunge into history, briefly describe future possibilities, and to motivate them to join the CTBTO Youth Group. It can serve as a springboard for considerable actions relating to the CTBT. We are deeply convinced that our generation is a generation that can change the world. We see that the future of the Organization and of the Treaty is youth. Our generation is full of strength and energy, we have a lot of opportunities and tools for implementation. Our world is changing rapidly, and we would like organizations to keep pace with these changes. Speaker: Ms Milana Ozerina (National Research Nuclear University MEPhI, Moscow, Russian Federation) • 11:00 Seismic Hydraulic Diffusivity a tool for Geothermal Exploration 15m The seismic hydraulic diffusivity is investigated to examine the implications fluid circulation has on the seismic activity at a geothermal prospect. The effect that fluid circulation has on the seismic activity is achieved by estimating the seismic hydraulic diffusivity from a source that originates from a point where the pore pressure propagates from for a distance (r) and time (t) from a single source that initiated the seismic swarms to each earthquake in the swarm. To achieve this aim the following objectives are satisfied; The location of hypocentral locations to outline the seismic event location and correlate them with the causative faults, determining the focal mechanisms to establish the style of faulting and fault plane orientation and to estimate the seismic hydraulic diffusivity to establish the source properties in the causative faults using the following formula; r^2= 43.14D*t where D is the seismic hydraulic diffusivity. To achieve this a dense seismic network is required, in most cases due to the cost limitations just a few stations are set-up. The data from the seismic IMS stations can be used to improve the quality of data as it adds up to the seismic network and also improves results accuracy. Speaker: Ms Magdalene Wangui Wanyaga (Marimant Geoexperts Ltd., University of Nairobi, Kenya) • 11:15 Challenges toward building a nuclear power plant in Kazakhstan 15m The first round of consideration of the construction of a nuclear power plant in Kazakhstan began in the mid-90s. The second time, with serious intentions, talking about construction of a nuclear power plant started in the mid-2000s. And for the third round, activity in the construction of a nuclear power plant in Kazakhstan dates back to 2013-2014 with government commission recommending two construction areas. No final construction decisions were made due to surplus of electricity. However with country’s electricity demand growing it is expected to have electricity shortage by 2030. Energy demand and economical sides of the project considered as reasons for delay of construction; however, there are far more reasons explaining why it would be challenging to progress with nuclear power plant construction in Kazakhstan. One of the main obstacles would be social rejection of the project due to trauma after nuclear weapon testing in Semipalatinsk area, with people still suffering from its consequences with growing rates of cancer and birth defects in area. All the tragedy and horror of the past left its deep wounds to Kazakh people. Also, lack of nuclear knowledge, communication to public, cultural security, and public awareness would be addition to the project delay. Speaker: Ms Kuralay Muratbekova (Ulba Metallurgical Plant JSC, Ust-Kamenogorsk, Kazakhstan) • 11:30 MEPhI Science Diplomacy Club: Building Bridges 15m A central tenet of MEPhI Science Diplomacy Club (SDC) activities is building bridges in the field of scientific and technological cooperation. The Club aims to construct an intergenerational dialogue by cultivating good working relations with high-profile experts in the field of non-proliferation, disarmament and nuclear test ban. The cornerstone of SDC policy is building educational and scientific bridges by providing a platform for youth from all over the world. The Science Diplomacy School “The NPT: Preserving the Legacy”, the II UN Security Council Model and Presentation Contest “My vision of the CTBT 2026” are prime examples of bringing students and experts from different profiles and raising awareness about current problems and pressing challenges. In addition, SDC maintains close ties with pre-university students by actively participating in summer practical seminars. It also attaches great significance to engaging female students with proactive attitude in its activities. It's time to make a difference and empower women to get to grips with science diplomacy issues. So, MEPhI Science Diplomacy Club opens up great opportunities for youth to network, share knowledge and exchange experiences. Speakers: Ms Anastasia Kulikova (Institute of International Relations, Moscow, Russian Federation) , Ms Varvara Belikova (Moscow Engineering Physics Institute (MEPhi), National Research Nuclear University, Moscow, Russian Federation) • 11:45 15 years achievements as NDC-TN 15m From 2006, when Tunisian IMS station (PS42 and IS48) started sending data, the NDC-TN has made a concerted effort to effectively participate in the verification regime of the Treaty and to implement obtained knowledge and capacities at the national, regional and international levels. This poster will give you an idea on how the NDC-TN: • Ensures the smooth functioning of the stations and the maintenance at the first level as well as its participation in various exercises relating to the updating of the hardware and software of stations, such as IS48 and SSI upgrades, calibration, et cetera; • Places a large importance on the development of national capacity building and the establishment of a methodology of work; • Prioritizes data analysis (SHI and R) and contributes to the promotion of civil and scientific applications. Speaker: Mr Noureddine Triqui (Centre National de la Cartographie et de la Teledetection (CNCT), Tunis, Tunisia) • 11:45 A book showing the importance of an NDC in Brazil for its better participation in the verification regime of the CTBT 15m Brazil does not have its NDC yet, but its creation has recently been discussed and, to contribute to these discussions, we have written the book The Brazilian Participation in the verification of CTBT, which presents the importance of an NDC, the advantages obtained with the its creation and demonstrated importance of CTBT in the control of nuclear weapons and in the construction of a solid social scientific knowledge base, through applications of the IMS data. Brazil participates in CTBT with three technologies (seismic, infrasound and Radionuclide). The book presents the locations of the last nuclear test carried out by RPDK and the accidental explosion in Beirut. There are several benefits for Member Countries with an NDC: access to raw and/or processed data; access to training and capacity building; access to software and technical support; access to a protected website that offers a platform for discussions and exchange of confidential information. By accessing the data of this worldwide network, Brazilian scientists will be able to develop studies and research in all areas of knowledge related to natural and man-made phenomena observable and measured by this worldwide IMS network. In this work we present the main subjects treated in the book. Speaker: Mr Lucas Barros (Seismological Observatory, University of Brasilia, Brazil) • 11:45 Analysis of the CTBTO scientific communication using network visualizations 15m The CTBTO Library has created an extensive analysis of the CTBTO scientific communication. This was possible using bibliometric and scientometric techniques, through key network visualizations to represent its contribution to the global scientific community during the last 25 years of international collaboration. In the context of the Comprehensive Nuclear-Test-Ban Treaty (CTBT) verification system, this analysis includes the content of more than 2,500 documents such as scientific articles, conference proceedings, reports, books, book chapters, expert reports, and dissertations (1996-2021) where experts in nuclear test detection from different backgrounds and types of institutions interact and contribute with innovative solutions to improve the verification regime. In this framework, the network visualizations offer an innovative approach to represent the complexity of this universe. With this technique, it has been possible to determine all the variety and diversity characterizing all the connections between experts, subjects of interest in common, institutions, and countries. This work was possible with the following software: a) Mendeley (free software), and b) VoSviewer (open software). The role of the Metadata was crucial, especially to standardize of author’s names, keywords, institutions, and countries. These representations express how clusters are interconnected, their co-occurrence, and relatedness based on the frequency of publications. Speaker: Ms Flor Elisa Trillo-Tinoco (CTBTO Preparatory Commission, Vienna, Austria) • 11:45 Baseline studies of environmental radioactivity in Nigeria to improve on-site inspection capabilities in regions with elevated radiation levels 15m Nigeria joined the international community to welcome the adoption of the Comprehensive Test Ban Treaty (CTBT) by the United Nations General Assembly on 10th September 1996, as a veritable tool to prohibit “any nuclear weapon test explosion or any other nuclear explosion” anywhere in the world. Nigeria signed and ratified the CTBT in September 2000 and September 2001 respectively. Baseline studies of environmental radioactivity and radiation mapping was conducted in Nigeria, to enable quick detection of elevated radiation levels due to cross boundary radiation from possible nuclear tests. Such data can be used to extrapolate activity at the test site, thus ameliorating the challenges of on-site inspection because of high radiation field, or where the test site is not within the jurisdiction of Nigeria. Nigeria, in her effort to ensure adequate and safe environment, carried out Environmental Impact Assessment in and around all its high risk facilities, Research Reactor in CERT, Zaria,GIF, Shada and medical facilities using Cobalt-60. Speaker: Mr Edemanwan Patrick Duke (Nigerian Nuclear Regulatory Authority, Abuja, Nigeria) • 11:45 Comparisons between the interactive seismological analysis softwares SEISAN and Geotool: advantages and disadvantages from the Venezuelan NDC perspective 15m The interactive seismological analysis system used by default at the Venezuelan NDC (Funvisis) is the SEISAN, which offers a complete package of programs for seismological analysis and for research purposes. Geotool, although it does not have a seismological research program package, is a software with a graphical interface that allows to display and analyze seismic events interactively. Both softwares can be customised and exteded, which is considered an advantage in these times of technological developments. SEISAN is used, commonly, through commands in the terminal, or command window, in the operating system in which it has been installed, in addition, the way to mark the seismic phases in the seismograms requires a lot of practice, making it prone to errors. On the other hand, Geotool has a friendly graphical interface that allows access to functions quickly and intuitively, such as observing statistics, errors and location parameters in a window within the interface and not in an uncomfortable terminal window. The advantage of SEISAN, regarding nuclear explosions and CTBTO's main aim, is its ability of making focal mechanisms, a procedure which is fundamental regarding the differentiation of a natural event from an artificial one. Speaker: Ms Alejandra Martinez Gonzalez (Fundación Venezolana de Investigaciones Sismológicas (FUNVISIS), Caracas, Venezuela) • 11:45 CTBTO Youth Academy of Sciences 15m This is the research and educational project for CYG members, which involves them in the CTBT research. The participants will work in groups of 4-5 people. Their research topic may include Verification Issues, Article XIV, CTBTO in the context of the nonproliferation regime, Science diplomacy, CTBTO and climate change, non-nuclear related applications of the IMS, et cetera. Each group will have a scientific supervisor from the GEM to bridge the younger and more experienced generation. The resulting papers are to be published in the Newsroom magazine, CTBTO web site and other platforms to revitalize discussion around the CTBT in the scholar's community be the voices of the young generation. Steps: 1) Pre-orientation online lectures on advanced issues related to the CTBT; 2) One-week online seminars on the CTBT key challenges to determine what kind of research is currently relevant and necessary to be conducted. The GEM members are involved in these seminars as speakers and mentors as they are to become research advisors of research teams; 3) One and a half to two months of research work of the research groups; 4) Publishing the results. Presentation of the results during the SNT or SDS in the presentation or poster sessions. The project intends to be an annual initiative. Speaker: Ms Kseniia Pirnavskaia (Korea Advanced Institute of Science & Technology (KAIST), Daejeon, Republic of Korea) • 11:45 CTBTO Youth Group as a prime model of track 2 diplomacy: united in science 15m CTBTO Youth Group represents a unique platform of almost 1000 members from diverse backgrounds,connecting science and policy in an interdisciplinary way. The platform provides opportunities through nuclear disarmament and non-proliferation education to involve its members in various track 2 diplomacy channels creating a safe space for active engagement, learning and exchange between peers coming from nuclear- and non-nuclear weapon states. This special type of interaction is possible through different dialogue possibilities available for the members, such as citizen diplomacy, science diplomacy, intergenerational cooperation and citizen journalism - fostering peace and collaborative atmosphere. Technological aspects of the CYG include the website with e-learning resources, connection via webinars and social media. These tools help to expand the network outside of nuclear field and attract more interest in the importance of banning nuclear testing, demonstrating support using a variety of means and contributing for the entry into force of the CTBT, highlighting its verification regime along with the scientific benefits. Speaker: Ms Marzhan Nurzhan (Parliamentarians for Nuclear Non-Proliferation and Disarmament (PNND), Czech Republic) • 11:45 CTBTO Youth Group Communications Model 15m The CTBTO Youth Group (CYG) was launched in 2016 and since then has around 1000 members. But this membership would not have been possible without effective and proper communication among members and with the CTBTO staff. The objective of the paper is to share successful communications model of the CTBTO Youth Group. The results suggest that this experience could be helpful for other youth organizations and further development of the CYG. Initially, the Group has a Coordination Team that represents the interests of the members and serves as the contact point between the CTBTO representatives (CYG Task Force) and all CYG members. Secondly, it has a CYG portal and social media accounts with the latest news and updates. Likewise, the CYG has a Newsletter that provides its members with information on recent and upcoming events and opportunities, as well as the articles on the CTBT-related topics. Next, Coordination Team members have a regular call with CTBTO staff to discuss strategies and events organization. Moreover, SnT and SDS serve as the platform for CYG members to meet in person and come up with the ideas on the CTBT's and CYG's promotion. Speaker: Ms Valeriya Korotchenko (National Research Nuclear University MEPhI, Moscow, Russian Federation) • 11:45 Determinants of Public Support for Nuclear Proliferation 15m What are the determinants of public support for nuclear proliferation? Fielding two survey experiments to nationally representative samples in a non-nuclear weapon state, we provide micro-level foundations for the acquisition of nuclear weapons. We find individual support for proliferation augments as existential threats loom large and it diminishes when external security is plentiful. Results also show that the presence of a powerful security guarantor tempers popular support for nuclear-weapon acquisition. But we also find that when it comes to issues of nuclear proliferation, psychology matters in a specific way: individuals who rank high on conservation values express preferences that align with rationalist incentives for and against proliferation more intensely than other members of the public. Speakers: Mr Matias Spektor (Getulio Vargas Foundation (FGV), Brazil) , Mr Guilherme Fasolin (Getulio Vargas Foundation (FGV), Brazil) • 11:45 Environmental consequences of nuclear disaster: 10 years of Fukushima Daiichi meltdown and the role of CTBTO in nuclear emergency response 15m Nuclear accidents are capable of exponential damage, and in particular can be the reason for acute environmental degradation. Radioactive contamination can occur for multiple reasons like damage in the nuclear reactors, from nuclear waste and also from the temporary storage of spent radioactive fuel. Radioactive emissions are fundamentally airborne and guarantees contamination for the next hundred years. In 2011, massive earthquake with tsunamis in Japan caused by the Fukushima Daiichi nuclear accident. Implications of the Fukushima Daiichi meltdown were not only regional but global at the same time. After the accident, an immense amount of radioactive materials was released into the atmosphere through varied meteorological conditions like wind and precipitation. CTBTO and its monitoring stations played significant role after the disaster to study the radioactive fallout and its consequences. The proposed paper is divided into two parts. Firstly, it will assess the environmental consequences of nuclear disaster in general. Secondly it will study the Fukushima Daiichi nuclear disaster and its implications on environmental degradation over the last 10 years. The paper will further evaluate the role of CTBTO to lay out a potential nuclear emergency response mechanism in the context of the disaster. Speaker: Ms Sweta Basak (Jawaharlal Nehru University, New Delhi, India) • 11:45 ESD, DRR and SDGs: Finding synergies, creating opportunities 15m In the midst of the Covid-19 pandemic, a need has arisen to rethink our way of working. As Disaster Risk Reduction and Mitigation is increasingly taking the spotlight so are education for Sustainable Development and the overarching framework of the SDGs. An important aspect that needs to be (re)considered to address future risks is the role education and life-long learning play. In this article we will analyse the risks of fake news and disinformation and its effects on effective interventions in emergencies, specifically for the CTBT this will also look at the importance of factual information and the added value of its seismometer network in ensuring quick and up to date information. Speaker: Mr Simon Herteleer (United Nations Economic Commission for Europe, Geneva, Switzerland) • 11:45 Importance of the National Data Centers (NDC) in the ratification of the CTBTO treaty. 15m Some countries have signed the CTBTO nuclear test ban treaty but are reluctant to ratify it. This can have several causes: Either their selfish aspect which can lead them to do not accept a total control by the preparatory commission of CTBTO, or the diplomatic relations are not very well strengthened between CTBTO and these countries. We believe that the installation of National Data Centers (NDC) in these countries can be a necessary tool to gradually bring them to the ratification of the treaty. The National Data Center promotes:  Continuous exchanges between the signatory country of the treaty and CTBTO  Strengthening diplomatic relations between CTBTO and the country With the National Data Center, CTBTO has the possibility of organizing scientific trainings and capacity building activities in these countries in relation with the verification regime. The delegates of CTBTO will therefore be able to go to these countries and meet there scientific and political figures who are in the position of decision-making. Such continuous exchanges can lead to very strong diplomatic relations that can push these countries to ratify the treaty. Speaker: Mr Didier Birimwiragi Namogo (Goma Volcano Observatory, Democratic Republic of Congo) • 11:45 Integrating realtime CTBTO and local seismic data using SEISAN 15m This presentation gives examples on how to process and analyse data obtained in realtime from the IMS through the newly developed SeedLink service available on the Global Communications Infrastructure (GCI), using the seismic analysis software package SEISAN. Furthermore, we show how to integrate sensor data and metadata and event parametric data from the CTBTO with locally collected data. SEISAN is used in more than 30 countries mainly at smaller seismic networks or by students or researchers, for processing data from permanent or temporary seismic networks and at a number of NDCs. SEISAN runs on both Windows and Linux and is freely available and open sources (see http://seisan.info). The examples include guides for: 1. Simple configuration of IRIS slarchive software for handling the SeedLink connection and local storage of the realtime data feeds from the IMS in SDS or BUD format. 2. Configuration of SEISAN for analysing data from the SDS in automatic and manual modes. 3. Merge IMS sensor metadata with the SEISAN database. 4. Create local versions of the IDC REB, SEB, SEL, etc. bulletins in SEISAN databases. Signals from teleseismic and local/regional events are used in the examples using the SEISAN virtual network functionality to include IMS data. Speaker: Mr Peter Henrik Voss (Geological Survey of Denmark and Greenland (GEUS), Denmark) • 11:45 Introduce nuclear to the common people culturally by keris 15m Introducing the concept of nuclear non-proliferation can be done with various approaches, including cultural approaches. Through the cultural approach, the introduction can be done by understanding the cultural products of a society, one of which is the Javanese society: a keris. As a cultural product, Javanese people use keris as weapons or accessories or collections. For the Javanese indigenous people, the keris is not just an object, it is also believed to have spiritual or mystical values. The keris is believed to provide strength to its owner. People who hold a keris or are near a keris may feel different sensations. Many researchers have found that the energy emitted by the keris produced by the constituent material which is a combination of iron, steel, nickel, cobalt, uranium and meteorite is the cause of the various sensations felt by the holder and the people around the keris. Various forms and phenomena surrounding the keris make it easier for the Javanese indigenous people to understand nuclear and radiation. Keris is an example of a cultural object that we can use to introduce nuclear to the common people through a cultural approach. CTBTO can increase awareness about nuclear to the wider community through cooperation with several local cultures. Speaker: Mr Arief R. Ismuharto (Indonesia Nuclear for Sustainable Benefits Promotor (INSuBP), Indonesia) • 11:45 Nepal in the arena of the CTBT 15m Nepal is a peace loving country and signed Nuclear Non-Proliferation Treaty (NPT) in 1970. Nepal became a Signatory of Comprehensive Test Ban Treaty (CTBT) in 1996 with the commitment of using nuclear energy in improving human health, world peace and prosperity and security - not for military purposes. The Nepalese Government has recently passed a law on Radioactive Material (usage and regulation) Act 2020. It has now opened the door for the peaceful use of nuclear applications for the benefit of the country under guidelines of International Atomic Energy Agency (IAEA) as being a Member State of the IAEA. Next, Nepal is surrounded by several nuclear installations of neighboring countries and is always at the risk of nuclear threats that may occur in its neighborhood. In this context, Nepal can benefit from IMS Laboratories under CTBTO's network especially in monitoring seismic activities and radionuclide monitoring. In this run, after being motivated through participation in the conferences of National Youth Council (NYC) under the Ministry of Youth and Sports, Government of Nepal. It is the right time for the government to engage youths in the activities of the CTBT. It is necessary to link NYC with the CTBT to carry out CTBTO's mission. Speaker: Mr Deepak Raj Shah Shah (Tribhuvan University, Nepal) • 11:45 Nuclear Harms & Slow Violence: Storytelling as Tool for Change 15m Storytelling can be a powerful tool for change and social activism. This essay proposes a storytelling blog as a platform to raise awareness and engagement with the goals of the CTBTO, namely, bringing the CTBT into force and working toward global deproliferation of nuclear weapons. Embracing Shampa Biswas’s broader conception of nuclear harms, such a project could work to make the harms of nuclear testing and other nuclear activities, such as uranium mining, intelligible and moving for a broad audience. This would align with Rob Nixon’s imperative to make slow violence – “violence that occurs gradually and out of sight, a violence of delayed destruction that is dispersed across time and space” – visible and arresting. Such a project could also make connections with the geographical concept of sacrifice zones, areas where environmental damage and economic disinvestment devalue life and wellbeing. Finally, a blog of this kind could make links to global environmental justice movements, which often focus on the location of sacrifice zones in marginalized, racialized communities; this project could therefore serve to connect the goals of the CTBTO to broader environmental movements and mobilize activists, organizers, and concerned citizens to pressure governments to bring the treaty into force. Speaker: Lindsey Palmer • 11:45 Open Day at IMS stations PS19 GERES and IS26 in the Bavarian Forest 15m The Primary Seismic Array PS19 GERES and the Infrasound Array IS26 are located in the Bavarian Forest and are operated by the Federal Institute for Geosciences and Natural Resources (BGR). From 2017 to 2019 extensive GERES refurbishment and recapitalization construction works were performed in the area which also had an impact for local population and tourists as cabling exchange disrupted hiking trails. After completion BGR organized an Open Day for the local population and tourists on 25 August 2019. Besides the chance to see the station elements, a comprehensive exhibition with information kiosks about CTBT monitoring, seismicity, infrasound sources and many other topics BGR is engaged with was provided. In front of the facility building a little folk festival with regional food and drinks as well as traditional brass music took place. During the day around 600 people visited the site at a remote place which seems kind of mysterious for the normal population. But after the open day they knew more about the purpose of the facility and the whole IMS an how monitoring works. Parts of the exhibition were also shown several weeks later when Vienna based diplomats were invited to visit the station site and facilities. Speaker: Mr J. Ole Ross (Federal Institute for Geosciences and Natural Resources (BGR), Hannover, Germany) • 11:45 OSI Exercises and Training – an Effective Way to Enhance Global Nonproliferation Efforts 15m OSI is the ultimate pillar of the CTBT verification regime. Available only after the Treaty’s EIF, it implies rapid deployment of a large amount of equipment and personnel. To maintain the operational readiness of the OSI segment, the CTBTO develops a network of exercises of different type and scale. Hosting an IFE, a BUE or an OSI Regional course is a process that requires a lot of resources – financial, human, administrative, political. What motivates a country to offer doing that? In this oral history project interviews were conducted with representatives of host countries and the PTS staff involved in IFEs (Kazakhstan 2008, Jordan 2014), BUEs (Austria & Hungary 2012-2013, Slovakia 2019-2021), Regional courses (Sri-Lanka, Argentina, South Africa). Further work requires defining the group of interviewees, specially from host countries around the following themes: determining the host country process; motivation for a country to host large-scale exercises; impact for a country (prestige, attempt to raise profile/role in global nonproliferation and disarmament efforts, contribution to science etc.) and domestic process of approving hosting of OSI exercises. The results of the study will be shared in this presentation. Speaker: Ms Anastasia Shavrova (CTBTO Preparatory Commission, Vienna, Austria) • 11:45 Outreach and Education through Museums and Cultural Centers 15m The creation of the CTBTO Youth Group is just one example of successful outreach and education being made accessible for individuals not already involved in nuclear/security circles. The entry into force of the Treaty is not just dependent on high-level talks but also influenced by civil-society. This is where museums, cultural, historical, and scientific centers are necessary for the communication of the CTBTO, the Treaty, etc. into the public consciousness. Such examples already exist to talk about nuclear testing and climate change (i.e "Godzilla: A Living Atomic Bomb" & "Nuclear Contamination and Climate Change" by Natural History Museum of Los Angeles County x The Los Angeles Times) and natural radiation (i.e. "Radioactivity in the Natural World" by Naturhistoriche Museum Wien). It would be in the organization and the treaty's best interest to explore new avenues for awareness and promotion as these learning centers are inclusive and non-discriminatory; possibilities of collaboration include but are not limited to: side events/panels, youth programs, exhibits (temporary and permanent). Speaker: Mr Cristopher Allan Cruz Colorado (Santa Monica College, CA, USA) • 11:45 Pathways Forward: Positioning the CTBT Among Other Arms Control Treaties 15m Due to stringent entry into force provisions, the Comprehensive Test Ban Treaty (CTBT) has yet to enter into force, despite a provenly effective comprehensive verification regime and widespread support. Meanwhile, the Treaty on the Prohibition of Nuclear Weapons (TPNW)--a more aspirational treaty with a broader scope and lower entry into force requirements--received enough ratifications to enter into force on October 24, 2020. Among other provisions, the TPNW prohibits the development or testing of nuclear weapons: language reminiscent of, though not identical to, prohibitions contained in the CTBT. This e-poster presentation explores how the current landscape of arms control treaties, including the Treaty on the Non-Proliferation of Nuclear Weapons (NPT) and the TNPW, affect the CTBT. It assesses: what are the legal obligations related to nuclear weapons testing under various arms control treaties? In what ways do the treaties reinforce one another? If one treaty poses a risk of undermining the CTBT, how can that risk be addressed, resolved, and transformed into an opportunity? In seeking to answer these questions, the presentation will incorporate the author's legal interpretation of treaty text, the results of expert interviews, and comparisons drawn from other areas of international law with complicated treaty landscapes. Speaker: Ms Brenna Gautam (Georgetown University, Washington, DC, USA) • 11:45 Scientific Promotion Programme for IMS data in Chile 15m The National Data Center in Chile is established at the Chilean Nuclear Energy Commission. Its principal mandate is to verify the compliance of the treaty and the storage of the data we receive. For this very reason, the NDC has a large amount of data available to be used by the scientific community. The problem is that this is not very well known today. To solve this issue, it started the Scientific Promotion Programme (SPP), whose objective is to develop data processing capabilities to promote their use in scientific research and to promote the diffusion of the CTBT and its benefits to our community. It offers opportunities to sign agreements with scientific institutions and ensure that this data is being used for pacific and civil purposes and not let its potential be neglected, because around the world, the potential of the IMS data to the promotion of science has been proven .This paper is about the steps followed to develop the SPP and the obstacles encountered during the process (for example: COVID-19) and the aspects that were identified and improved due to this programme at the Chilean NDC. Speaker: Mr Christopher Celis Huaiquilaf (Chilean Nuclear Energy Commission (Comisión Chilena de Energía Nuclear), Santiago, Chile) • 11:45 Study of Perception of Pacific Islander’s students at Otago University New Zealand about CTBTO 15m Pacific Island member countries have a combined population of about 2.3 million people. Nuclear tests in these islands significantly impacted humans and environment. More than 300 nuclear tests were carried out in the Pacific from 1946 to 1996 in the atmosphere, underground and underwater. Recently Prime Minster of Fiji, made a statement on behalf of 12 Pacific countries to UNGA and presented vision that “the blue Pacific Ocean will become an ocean of peace and prosperity for our people and the world and it could only become an ocean of peace if it was nuclear-free”. To reflect his statement, we have conducted a study among pacific islander students enrolled at University of Otago, Dunedin New Zealand about their perception about Comprehensive Test Ban Treaty (CTBTO). We have received response from total 80 students (35 male, 43.75% and 45 females, 56.25%). Only 45% (36) students have knowledge about CTBTO and only 70% (56) knows about nuclear testing. This shows there is still lack of awareness about young generation of pacific islanders about ban on nuclear testing and it require special education and online awareness campaign is required to build momentum against nuclear testing among young generation. Speaker: Mr Muhammad Qasim (University of Otago, New Zealand) • 11:45 Teaching Humanitarian Impacts of Nuclear Weapons as Part of CTBT Education: Case of Kazakhstan 15m There is a growing understanding in the international community of the catastrophic humanitarian consequences of the use of nuclear weapons on individuals, society, the economy and the environment. However, recent efforts by non-nuclear weapons states and civil society to encourage nuclear powers to prioritize nuclear disarmament that culminated in the adoption of the Treaty on the Prohibition of Nuclear Weapons have not been successful. There is a clear need to revitalize the humanitarian impacts agenda, which will also help promote the CTBT’s entry into force. One of the ways is to educate the young generation by incorporating humanitarian aspects of nuclear weapon detonations in academic curricula of relevant higher education institutions. In Kazakhstan, a country that housed a major nuclear test site and is now home to five International Monitoring System stations, a number of universities offer non-proliferation and disarmament courses that comprehensively cover, among other topics, nuclear test-ban issues, including CTBT’s political and legal aspects, as well as health and environmental consequences of nuclear testing. This experience demonstrates that educated youth equipped with necessary knowledge can be instrumental in achieving progress towards a world free from nuclear weapons. Speaker: Mr Dauren Aben (Eurasian Research Institute, Almaty, Kazakhstan) • 11:45 The Impact of Capacity Building Project on Jordan NDC 15m The CTBTO capacity building project includes a capacity building system (CBS), training courses, technical visits, et cetera. The CBS that has been established in Jordan is helpful in integrating data acquisition, processing and analysis using the NDC in a box, which was developed by the IDC. The training courses and technical visits helped on how to use the CBS and software package (NDC in Box), and how to access to the IMS data and IDC products by requesting the data from IDC product then analysing this data by using different software (GeoTool, SeisComP 3, et cetera). In this poster we describe how the capacity building project has improved the Jordan NDC and developed the staff's experience, knowledge and skills. Speaker: Mr Murad Alhomaimat (Jordan Seismological Observatory (JSO), Amman, Jordan) • 09:00 10:00 e-poster round table - P1-RT1: e-poster round table - T1.1 & T1.3 Stage 1 (Online) ### Stage 1 #### Online E-poster round tables for: - T1.1 - T1.3 Conveners: Mr Pierrick Mialle (CTBTO Preparatory Commission, Vienna, Austria) , Mr Peter Louring Nielsen (CTBTO Preparatory Commission, Vienna, Austria) • 10:00 11:00 e-poster round table - P1-RT2: e-poster round table - T1.2 & T5.3 Stage 1 (Online) ### Stage 1 #### Online e-poster round table for: - T1.2 - T5.3 Conveners: Mr Haijun Wang (CTBTO Preparatory Commission, Vienna, Austria) , Ms Misrak Fisseha (CTBTO Preparatory Commission, Vienna, Austria) • 11:00 11:30 Series of talks on 25 years of CTBT: Seismic technology: Special talk Location 1 (Onlince) ### Location 1 #### Onlince 25 years of CTBT: progress on verification technologies and looking towards the future 25 years and beyond • 11:00 New applications at the IDC for SHI Expert Technical Analysis 30m The Preparatory Commission for the CTBTO (Commission) routinely process time-series data from a global network of seismic, hydro-acoustic, and infrasound (SHI) stations. The data are processed to detect, build, locate, and screen events that may have characterization parameters similar to those from nuclear explosions. The observation and processing systems are required to be sensitive to small (e.g. low-magnitude) events, especially in unusual locations (e.g. aseismic regions). In order to match this requirement and to assist the State Parties to identify the source of specific events the IDC develops services combined in one SHI Expert Technical Analysis (ETA) Suite. The Parametrical Moment Tensor Estimator, ParMT (depth and magnitude determination through the moment tensor estimation) and the IDC historical master event-based Spot Check Tool, SCT, are the ongoing IDC developments. A promising avenue to improve the ParMT results, as well as for enhancement of IDC (mostly regional) locations, is to embrace the Ambient Noise Tomography technique in IDC practice. Receiver velocity models underneath IMS stations can be improved using the vast amount of gathered seismic background data. The same approach can be utilized for OSI data processing using the ANT-based velocity models produced with the noise data from SAMS array. Speaker: Mr Ivan Kitov (CTBTO Preparatory Commission, Vienna, Austria) • 11:30 12:30 Event 1 - Resilience of the CTBT monitoring regime: Event Stage 3 (Online) ### Stage 3 #### Online Convener: Mr Thomas Ludwig Hoffmann (CTBTO Preparatory Commission, Vienna, Austria) • 11:30 Event 1 on Resilience of the CTBT monitoring regime, including lessons learned from the COVID-19 pandemic crisis 1h The COVID-19 pandemic is a major topic of interest for the SnT2021. The global nature of it produced a resilience test for many, and in particular for a global monitoring system, such as the CTBTO’s, that relies on continuous data gathering, transmission and analysis. The objective of this series of two events is to provide the audience with pertinent case histories and lessons learned from IMS stations e.g. during O&M activities, station upgrades or logistics challenges, faced by the station operators and PTS during the restrictions imposed by covid-19. Topics presented in Event 1 are (i) the steps taken to ensure operation and maintenance activities for optimal performance of the IMS stations IS32 and PS24 in Kenya during COVID-19 restrictions, (ii) the upgrade of five auxiliary seismic stations in Japan and how the COVID-19 limitations and restrictions were overcome, (iii) restrictions under the COVID-19 crisis imposed on the operation and maintenance of the radionuclide stations RN37 and RN38 in Japan and how JAEA is working with PTS, manufacturers of RASA and SAUNA, and local operators in order to overcome this challenge, (iv) timeline of the active cases at IS42 infrasound station in the Azores, Portugal, the related constraints and O&M actions taken, with PTS support, to guarantee the Mission Capability of the station. (v) CTBTO/OSI will present a brief review of the OSI Training section’s interventions, designed to mitigate the loss of onsite technical training and achieve and maintain true blended learning during and after COVID-19 and (vi) CTBTO IMS/MFS will share examples of logistics and maintenance cases that could have affected data availability and show contingency measures that were implemented. Speaker: Mr Thomas Ludwig Hoffmann (CTBTO Preparatory Commission, Vienna, Austria) • 11:30 13:00 Panel discussion on Lessons from historic nuclear test explosions and value of recorded signals for monitoring science: Panel discussion Location 1 (Online) ### Location 1 #### Online • 11:30 Lessons from historic nuclear test explosions and value of recorded signals for monitoring science 1h 30m The nuclear tests announced by the DPRK provided an opportunity to test methods and gain experience with respect to the estimation of the absolute and relative event location, depth and magnitude. However, this experience is limited to one specific test location. Much broader experience can be gained by applying modern analysis methods to the vast amount of data recorded on more than 2000 historic nuclear test explosions. To support such developments, valuable progress towards preserving and making available for research digitized data of historic nuclear explosions has been made. The goal of this session is to identify the priorities for continuing and expanding these efforts. Historic data are needed from as many as possible different regions and geological characteristics. Signals should be preserved from tests in the atmosphere, underwater and underground. While most ongoing efforts focus on seismic data, the historic hydroacoustic and infrasound data are rare and radionuclide data are sparse. Speaker: Mr Rong Song Jih (U.S. Department of State, USA) • 13:30 14:30 Highlight talk on the Solid Earth and its Structure: Highlight talk Stage 1 (Online) ### Stage 1 #### Online Convener: Mr Gerhard Graham (CTBTO Preparatory Commission, Vienna, Austria) • 13:30 Imaging the Earth's Deep Interior using seismic waves 1h Forty years ago, the first global seismic tomographic models revealed the presence of two large, antipodal, structures at the base of the Earth's mantle, now known as "large low shear velocity provinces" (LLSVPs), that had no obvious relation to surface geology or mantle dynamics as understood from plate tectonics theory, and as reflected in near surface seismic structure. With the expansion of digital, very broadband seismic networks and related on-line databases, combined with improvements in theory and computer power, the resolution of mantle elastic structure has progressively improved. In this lecture, I will illustrate how state-of-the-art imaging techniques allow us to: track the fate of tectonic plates that dive back into the mantle beneath the Pacific "ring of fire", improve our understanding of the morphology and role of the LLSVPs, and follow the paths of deeply rooted hot mantle plumes, as they ascend towards the surface and are expressed there in the form of hotspot volcanism (of which Hawaii and Iceland are prominent examples). I will present some of the open science questions, technical challenges for further progress in full waveform tomography, as well as possible paths ahead to address them, combining tools from seismology and other geophysical disciplines. Speaker: Ms Barbara Romanowicz (University of California, Berkeley, CA, USA) • 13:30 15:30 T2.4 - Atmospheric and Subsurface Radionuclide Background and Dispersion: Oral session Stage 2 (Online) ### Stage 2 #### Online oral session Convener: Ms Jolanta Kusmierczyk-Michulec (CTBTO Preparatory Commission, Vienna, Austria) • 13:30 Session introduction 5m • 13:35 Six months of radioxenon detections by the SPALAX New Generation system near Paris in 2019 15m As part of its qualification process by the PTS, the SPALAX-NG - noble gas - New Generation system was operated from October 2018 to April 2019 on the CEA/DAM premises near Paris (France). The new generation system’s high performances contribute significantly to increase the number of detections and to improve the knowledge of the radioxenon background. Indeed, in this study, a major dataset including numerous isotopic ratios is established for Western Europe that enables to refine the characterization of the background sources and the discrimination criteria. In addition, a full Atmospheric Transport Modelling study has been performed from this full dataset, that allows to 1/ reconsider the radioxenon source terms of the main emitter in Western Europe (IRE, Fleurus, Belgium), and to 2/ detect for the first time some very local and non-traditional sources that can influence the categorization of a detection. Speaker: Mr Pascal Achim (Commissariat à l’énergie atomique et aux énergies alternatives (CEA), France) • 13:50 Statistical study of the IMS 133Xe data distributions, using both a parametric and a non-parametric method 15m The aim of this work is to apply both a parametric and a non-parametric statistical method to the 133Xe activity concentrations measured at noble-gas stations of the IMS of the CTBTO, in order to investigate the atmospheric background and the anomalous values. The parametric method consists of two control charts: a single-observation chart sensitive to large variations with respect to the mean value, and an EWMA chart sensitive to small variations with respect to the mean value. The results show that the control charts could be useful for an NDC carrying out daily monitoring to easily detect significant variations of the activity concentrations, and to perform more specific analysis of the anomalous values. The parametric method is expected to be useful to better understand the false positives. The non-parametric method is based on a Recursive Segmentation and Permutation (RS/P) algorithm, it does not require any assumption about the underlying probability distribution, and it associates a significance level to the results. The RS/P method is useful for detecting single or multiple mean shifts and/or scale shifts, and the results show that it can be useful to highlight any random oscillations of the phenomenon providing a likely better understanding of anomalous values. Speaker: Mr Giuseppe Ottaviano (Italian National Agency for New Technologies, Energy and Sustainable Economic Development (ENEA), Italy) • 14:05 Statistical study of the Cs-137 detections at RN43 station 15m This work is the result of a joint collaboration between the Italian and the Mauritanian National Data Centers. Radionuclide station RN43 in Mauritania was established in Nouakchott on 6 November 2006. The historical analysis of the occurrence of relevant radionuclides at RN43 over the past ten years showed that the main contributor was Cs-137, causing several level 3 and level 4. A descriptive statistical analysis of the Cs-137 occurrence was performed and two types of parametric process control methods were applied: the “Shewhart Control Chart” and the “Exponentially Weighted Moving Average (EWMA) Control Chart”. The results of both methods were then analyzed in order to reveal seasonality, possible sources of Cs-137 and correlation with atmospheric phenomena. Speaker: Mr Mohamed Mahmoud Mounja (Mauritania National Authority of Radiation, Safety and Nuclear Security (ARSN), Nouakchott, Mauritania) • 14:20 First observations of environmental 125Xe, 127Xe, and 129mXe 15m Environmental 125Xe, 127Xe, and 129mXe have been observed during testing of a next-generation xenon measurement system, Xenon International. The observations of these three radioxenon isotopes occurred during routine testing at the Xenon International manufacturing facility in Knoxville, Tennessee, USA, and they are believed to be the first observation of these isotopes in environmental samples collected by automated radioxenon systems. The observations are consistent with activation of xenon in air and have been attributed to the High Flux Isotope Reactor (HFIR) located at the Oak Ridge National Laboratory, about 20 km away. The 125Xe, 127Xe, and 129mXe isotopes can be detected in the beta-gamma detector of Xenon International and would interfere with the quantification of the radioxenon isotopes used for nuclear explosion monitoring. The interferences would cause elevated concentration values for the radioxenons of interest in the current analysis methodology. The 125Xe was observed the most often, and it decays to 125I, which can also interfere with radioxenon measurements in the beta-gamma detector. This presentation will describe the observations, production mechanisms, implications for IMS systems and possible mitigation strategies. Speaker: Mr James Ely (Pacific Northwest National Laboratory (PNNL), Richland, WA, USA) • 14:35 Results of the 3rd ATM-Challenge 2019 15m Estimating the radioxenon background based on a multi-input-multi-model ensemble modelling approach at IMS stations having frequent detections was the main goal of the 3rd ATM-Challenge. The Challenge included four selected IMS stations. Participants were invited to calculate contributions to the signal captured in daily samples at CAX17 (St. John’s), DEX33 (Schauinsland/Freiburg), SEX63 (Stockholm) and USX75 (Charlottesville) for up to 6 months. Up to 30 submissions per station from 16 different institutions were finally received. Xe-133 stack emission data with daily temporal resolution for the time period June to November 2014 provided by IRE (Belgium) and CNL (Canada) radiopharmaceutical plants were used. In addition, publicly available emission estimates for nuclear power plants and research reactors as well as annual emissions from other several well-known facilities were also made available to participants. The presentation will summarize the comprehensive results from this study. First, the added value of training an optimized ensemble per station will be discussed. Second, the beneficial impact of including contributions from minor emitters and thus rough emission estimates thereof will be demonstrated. The added value of simulating samples highly influenced by main emitters, i.e. radiopharmaceutical plants, based on actual daily emission data will be exemplified. Speaker: Mr Christian Maurer (Central Institution for Meteorology and Geodynamics (ZAMG), Vienna, Austria) • 14:50 Production of Mo-99 without Use of Uranium 15m NorthStar has embarked on two parallel paths to produce Mo-99 and other medical radioisotopes without use of any uranium material. The first path, which was approved by the US FDA in February 2018, is via neutron capture utilizing a research reactor. In this pathway, NorthStar can use either high-purity natural molybdenum discs or can use target material of enriched molybdenum-98. This pathway has successfully been producing Mo-99 and delivering to the US market for more than two years. The second path, scheduled for production start in late 2022, is the use of electron accelerators to perform photon transmutation using enriched molybdenum-100 target material. In either case, NorthStar’s emissions of gaseous radioisotopes of krypton, iodine or xenon are virtually non-existent. This presentation will provide a review of the production processes and an update to current program status. Speaker: Mr James Harvey (NorthStar Medical Technologies, LLC, Beloit, USA) • 15:05 3-D electrical imaging of mesoscale rock damage patterns from underground chemical explosions 15m Atmospheric gas detection is a primary means for detecting and verifying underground nuclear explosions. Subsurface gas migration is governed by a complex system of unknown variables, including the interaction between geology, explosion-induced stresses and corresponding rock damage patterns that provide primary gas flow pathways. The U.S. is conducting a series of highly instrumented mesoscale experiments that provide an opportunity to better understand the interaction between source strength and location, natural variations in rock competency, explosion-induced rock damage, and gas migration. Rock damage is imaged in 3-D using a novel combination of water injection, draining, heating and drying combined with time-lapse electrical resistivity tomography. Corresponding measurements of induced gas breakthrough times at discrete points in exterior monitoring wells are being used to understand how rock damage is influenced by local geology, and how it influences gas migration away from the source point. Results show that the influence of geologically weak zones on rock damage and gas flow are comparable to the influence of source strength and location. This result has important implications for larger scale underground explosions, and how those explosions interact with geology and alter gas migration flow paths and travel times to the surface. Speaker: Mr Tim Johnson (Pacific Northwest National Laboratory (PNNL), Richland, WA, USA) • 13:30 15:15 T5.3 - Capacity Building, Education, Communication and Public Awareness: Oral session Location 3 (Online) ### Location 3 #### Online Convener: Ms Zeinabou Mindaoudou Souley (CTBTO Preparatory Commission, Vienna, Austria) • 13:30 Session introduction 4m • 13:34 Role-play simulations as effective participatory learning techniques in science diplomacy education 15m MEPhI Science Diplomacy Club (SDC) aims to nurture a new generation of experts who are curious about cross-cutting issues at the interface of science and international relations, who are willing to bridge diplomatic challenges & technical solutions and who are eager to learn more about current challenges including nuclear test ban, non-proliferation and disarmament. The SDC members participate in a wealth of outreach and education activities comprising webinars with experts, presentation contests, summer seminars for pre-university students, Science Diplomacy School, career talks etc. Due to restrictions caused by the COVID-19 pandemic, we had to fully utilize evolving pedagogic methods including distance learning and videoconferencing with a view to holding SDC events in a remote format. We’ll use the occasion of the SnT21 to share our experience of incorporating simulations and role-plays, which are deemed to be one of the most effective participatory learning techniques, into multidisciplinary educational programs. Moreover, we’d like to share our main learnings from The 2020 NPT Review Conference Model which not only highlighted the NPT-CTBT nexus but also showcased the distinct role of the CYG in increasing the visibility of the CTBT. Speaker: Ms Elena Tsyvkunova (National Research Nuclear University MEPhI, Moscow, Russian Federation) • 13:49 Scientist and Diplomats On Site! 15m In the context of the nuclear non-proliferation regime, the On-Site Inspection of the CTBTO play a mayor role for verification. OSI is when Scientists from different fields and diplomats get together with a common aim: “to identify signs from a nuclear explosion”. Only a perfect match between science knowledge and diplomatic skills can assure full success for an OSI. The crucial issue is how to prepare both to be ready to go in to the field and interact properly using a common language and having the same training and motivation. For this to happen diplomats must correctly learn not only about the whole range of technologies involved in an OSI but to experiment in field exercises in order to confirm without any doubt that the data arising from scientific work are reliable, trustworthy and can be used for a proper decision at the political level. Speaker: Gustavo Gonzalez (Ministerio de Relaciones Exteriores de Chile, Chile) • 14:04 Utilization of CTBT-NDC data in geoscience education of Bangladesh 15m Bangladesh, a Comprehensive Test Ban Treaty (CTBT) signatory country since 24 October, 1996, is the 54th state to ratify CTBT on 8 March, 2000. Auxiliary Seismic Station (AS007 BRDH) in Bangladesh, accredited as an internationally certified station, receives the seismic data from International Data Center (IDC) of CTBTO. The seismic station AS007 was established to monitor the activities of nuclear testing through seismic wave propagation in the region. Geoscientists of different academic and professional institutions have been analyzing seismic travel time data from various sources. Accordingly, the objective of the present report is to find out the potential application of regional seismic travel time (RSTT) data in the geoscience researches of Bangladesh. The RSTT data can be applied to analyze this subsurface geological information with the combination of other CTBT seismic stations of the region. Besides seismic data, the IDC has other products, such as radionuclide and noble gas distribution data around the world, hydro-acoustic data for tsunami warning system, etc. Therefore, there is ample scope of introducing IDC products to the geoscience education of Bangladesh. As part of R&D activities through the CTBT-NDC, BAEC is working on this aspect by collaborating with the geology departments of several universities. Speaker: Mr Mohammad Rajib (Bangladesh Atomic Energy Commission, Dhaka, Bangladesh) • 14:34 Knowledge Management in the Context of Comprehensive Nuclear-Test-Ban Treaty (CTBT) Science and Technology 15m In support to the Comprehensive Nuclear-Test-Ban Treaty, the worldwide scientific community - via the CTBT SnT Conferences - has the opportunity to build partnerships and encourage knowledge exchange, allowing the CTBTO to remain at the forefront of the relevant technology for test-ban verification. The SnT Conferences are organized biennially by the Preparatory Commission for the Comprehensive Nuclear-Test-Ban Treaty Organisation (CTBTO). This paper analyses the CTBT SnT topics presented at the Conferences from 2006-2021, capitalizing on scientific and technological applications, trends, innovations and worldwide collaborations. The goal of this work is to provide directions on the knowledge management approach for deep content analysis, strengthening the role of Knowledge Organisation Systems (KOS) as a mechanism and tool for analysing and disseminating content. This research reflects the necessity of creating a KOS-based tool for knowledge recognition and discovery that will encourage communication in a valuable way. Speaker: Ms Marija Sejmenova-Gichevska (Former CTBTO Preparatory Commission, Vienna, Austria) • 14:49 Banning Nuclear Tests: The Role of Public Opinion Research 15m In recent years, there has been a rapid increase in social scientific studies using polling techniques to better understand nuclear issues. Scholars have shown public opinion in numerous countries on subjects such as nuclear proliferation, deterrence posture, and links between civilian and military nuclear technologies. These studies are important contributions for improving decision-maker accountability and more effectively shaping policy to represent public views. We contribute to these discussions by presenting new public opinion data on nuclear explosive testing. The data come from nationally representative surveys we conducted in Belgium, France, Germany, Italy, Japan, the Netherlands, Poland, Sweden, Turkey, the United Kingdom, and the United States. The surveys demonstrate overwhelming public opposition to nuclear testing while also revealing (mis)perceptions about the effects of nuclear test explosions. Taken together, they provide useful information for policy, advocacy, and education aimed at promoting entry-into-force of the Comprehensive Nuclear-Test-Ban Treaty (CTBT). Speaker: Mr Stephen Herzog (Yale University, CT, USA) • 15:04 Concluding remarks 10m • 14:30 15:30 The 25th anniversary for opening the CTBT for signature: invited talk on Seismic technology: Invited 25th anniversary talk Stage 1 (Online) ### Stage 1 #### Online Convener: Mr Gerhard Graham (CTBTO Preparatory Commission, Vienna, Austria) • 14:30 Challenges and Achievements of Monitoring for Nuclear Test Explosions in the Context of the CTBT 1h Close acquaintance with details of the CTBTO’s International Monitoring System and the International Data Centre can tempt a keynote speaker to present the work as highly complicated, with success coming only via enormous effort. But stepping back from details such as the very size of datastreams received by headquarters in Vienna, and of datasets accumulated after nearly 25 years of operations, it is more important to note the main achievement of the IMS and IDC — namely that the CTBTO draws appropriate attention to events which member States can choose to study in greater or lesser detail. Intense efforts can then be brought to bear on events of particular interest, as deemed necessary by any data user. This presentation will review the basic steps in detecting and analyzing the variety of types of signals generated by nuclear test explosions. It will then present examples of how nuclear test explosions were recorded, first in the earliest days of nuclear weapons development; how these data changed over the forty years leading up to the agreed CTBT text of 1996; and then how data acquired in the present century can be processed using the latest methods applied to broad areas. Speaker: Mr Paul Granston Richards (Lamont-Doherty Earth Observatory of Columbia University, New York, NY, USA) • 15:45 17:30 T1.2 - The Solid Earth and its Structure: Oral session Location 2 (Online) ### Location 2 #### Online Convener: Ms Nurcan Meral Ozel (CTBTO Preparatory Commission, Vienna, Austria) • 15:45 Session introduction 5m Location 2 (Online) ### Location 2 #### Online • 15:50 Monitoring sub-seafloor deformation in plate subduction zone 15m Location 2 ### Location 2 #### Online Fault rupture in a subduction zone often causes devastating earthquake and tsunami hazards. Therefore, understanding a slip behavior along the fault is a crucial scientific topic and a deeply socially relevant problem. To understand the slip behavior along the fault, there are two kinds of essential geophysical datasets. One is seafloor displacement as a surface response of a fault slip, and the other is the sub-seafloor structure, which is needed to transform a surface displacement to a fault displacement. Recent studies reveal that surface displacements due to fault slips show a wide-spectrum of their frequency, from a regular earthquake (~10 Hz) to a long-term slow slip (~months). To monitor the entire spectrum of the fault slip, monitoring the displacement with a seismo-geodetic band in real-time continuously is necessary. And also, to transform the displacement to the slip along the fault, it is essential to know a realistic structure of a medium (lithospheric structure) in the subduction zone. JAMSTEC is conducting an integrated geophysical project to establish a real-time continuous seafloor geodetic network in the Nankai Trough, Japan, and construct a three-dimensional structural model using seismic data. We will present an outline and recent results of the project in this presentation. Speaker: Mr Shuichi Kodaira (Japan Agency for Marine-Earth Science and Technology, Yokosuka, Kanagawa, Japan) • 16:05 [NO SHOW] Velocity structure of the uppermost mantle beneath the tanzanian craton and the surrounding proterozoic mobile belts from pn tomography 15m Location 2 ### Location 2 #### Online The uppermost mantle structure beneath East Africa is investigated by inverting the Pn traveltimes to obtain a model of P wave velocities. The previous Pn tomography models of the region have been expanded. A total of 2870 new Pn travel time measurements of local and regional earthquakes have been made and modeled, improving the resolution of the uppermost mantle velocity structure across much of East Africa. The new Pn tomography model shows variations in uppermost mantle velocities across the region which can be used to understand the size of the Tanzania Craton and the differences between the Eastern and Western branches of the East African Rift System (EARS). Results reveal fast Pn velocities beneath the Tanzania Craton, the extension of these fast velocities beneath the Mozambique Belt to the east of the craton, the Kibaran Belt west of the craton, and beneath the northern half of the Ubendian Belt to the southwest of the craton. In addition, the fast Pn velocities beneath the Western Branch everywhere contrast with the slow Pn velocities of 7.5-7.8 km/s beneath the Eastern Branch in Kenya, showing that the upper mantle beneath the Eastern Branch has been altered much more than beneath the Western Branch. Speaker: Ms Nada El Tahir (University of Khartoum, Sudan) • 16:20 A crustal P-wave velocity model for Israel to improve IMS capabilities in the Middle East 15m Location 2 ### Location 2 #### Online The Israeli National Data Center is responsible for monitoring and characterising the seismicity of the Eastern Mediterranean region. The accuracy of seismic locations is mostly affected by the velocity model used, and no clear picture of the variations in seismic velocities in Israel has emerged in the recent years. We gathered a large dataset of seismic travel times recorded in Israel and nearby countries. After quality control and joint relocation of over 30,000 natural and man-made seismic events, we produced a revised dataset of more than 500,000 arrivals. From this dataset, we inverted Pg and Pn travel times for a crustal velocity model of the area using the FMTOMO tomographic inversion package. In order to do this, we put together a 3-D starting model that consists of an ensemble of 1-D velocity profiles for the various tectonic settings observed in the region. We present images extracted from this model, as well as corresponding synthetic resolution tests to assess the quality of our results. This high-resolution model is to be integrated into the Regional Seismic Travel Time model and procedure in order to enhance the CTBT’s International Monitoring System capabilities in the Middle East. Speaker: Mr Lewis Schardong (Tel-Aviv University, Israel) • 16:35 3D Dynamic Earthquake Rupture Simulations In The Sea Of Marmara 15m Stage 2 ### Stage 2 #### Online The center of the Sea of Marmara, the region between the locations of 1912 Mürefte and 1999 Izmit M_w7.4 earthquakes, is prone to creating a large earthquake. The main objective of our study is to determine 3D dynamic earthquake rupture scenarios, considering non-planar and heterogeneous stress distribution in the Sea of Marmara. In this study, it is the first time that we attempt to generate realistic earthquake scenarios by putting constrains on initial stress on the fault using regional stress from earthquake focal mechanisms, in addition to stress release during past earthquakes and strain accumulation during interseismic period using geodetical measurements on slip-rate and locking depth at various segments. We use 3D Finite Element Method (PyLith) for dynamic earthquake simulations and tetragonal mesh for better smoothing at the fault bends, which allows us to implement nonplanar fault geometry and initial stress heterogeneity using slip-weakening friction law. We place constraints on initial shear stress from geodetic and seismic studies of locking depth and interseismic strain accumulation. We consider more than a hundred rupture scenarios and calculate slip distribution, rupture velocity and moment magnitude in addition to slip-rate and traction on the fault surface, and displacement and velocity on the ground surface. Speaker: Ms Yasemin Korkusuz Öztürk (Bogazici University, Istanbul, Turkey) • 16:50 Teleseismic depth determination, techniques and uncertainties : an Himalayan case study 15m Location 2 ### Location 2 #### Online Accurate estimates of the depth of seismic events allow determining whether they are associated to a given tectonic structure. It is also a good discriminator between earthquakes and explosions. However, automatic depth determination at teleseismic distance remains a challenge: the depth phases (pP, sP), reflected on the free surface, are sometime difficult to pick in the teleseismic signal. This is particularly true when the events are intermediate magnitudes (Mw<5), and fall at shallow depths in complex tectonic environments. To overcome that challenge, we implement two teleseismic depth estimation methods : (1) a cepstral analysis allowing to extract the pP-sP reflected waves in a the P-coda from their phase's similarity with the direct P wave and (2) an envelope stacking procedure aiming to highlight these secondary arrivals from their energetical contents. These two complementary methods allow improving signal over noise ratios and automatically identifying coherent depth phases among the thousands of teleseismic stations and arrays available from global teleseismic networks, including those of the International Monitoring System monitored by CTBTO. We confront our results to a set of well determined regional depths determined from a dense temporary network deployed in the Nepalese Himalayas, a region of high-topography and relatively shallow seismicity. Speaker: Ms Marine Laporte (Commissariat à l’énergie atomique et aux énergies alternatives (CEA), France) • 17:05 P-wave arrival-time tomography of the Middle East 15m Location 2 ### Location 2 #### Online High-resolution tomographic images of the MiddleEastern region are essential to accurately locate ground motion events during nuclear monitoring programs. The purpose of this study is to retrieve detailed models down to lowermantle beneath the Middle Eastern region using a set of reliable regionally observed teleseismic P arrival times from the ISC-EHB bulletin (Engdahl et al., 1998). Our current inversion results are consistent with the previous regional tomographic studies. In checkerboard tests of cell dimension as low as\sim2.4^{\circ}$($\sim$280 km at surface) are well recovered down to a 1000 km depth beneath the Anatolian plateau where we currently have the densest coverage with ISC data. The Caucasus region and northern parts of the Iranian plateau shows good recovery of$\pm4\%$Vp perturbation amplitudes at depths$\sim$70 – 135 km. There is fair recovery for a minimum of$\sim2.4^{\circ}$cell size beneath the Iranian Plateau, Zagros mountain region, Persian gulf, and northeast Iraq. We are able to further improve coverage especially down to lithospheric depths within the Arabian peninsula using first arrival times measured from waveform data collected from regional networks. The ultimate goal is to perform full-waveform inversion of the region constrained by the constructed P-wave model. Speaker: Ms Ebru Bozdag (Colorado School of Mines, CO, USA) • 17:20 Concluding remarks 10m Location 2 (Online) ### Location 2 #### Online • 15:45 17:15 T3.6 - Artificial Intelligence and Machine Learning: Oral session Location 3 (Online) ### Location 3 #### Online • 15:45 Session introduction 5m • 15:50 Beta-Gamma coincidence radioxenon spectra classification using the convolution neural network (CNN) technique 15m In this study, using a machine learning method, in particular, a deep learning approach, we propose for the first time a model of Beta-Gamma coincidence radioxenon spectra classification. Specifically, by means of real data from the noble gas system in Charlottesville (USX75) as part of the International Monitoring System (IMS) operated by CTBTO between 2012 and 2019, we apply the convolution neural network (CNN) technique based on the absolute concentration of each radioxenon isotope. The results show that without utilizing background spectra, interference corrections, and without determining the activity concentration of each isotope, the automatic classification can be carried out with high accuracy. This implies that categorization through deep learning does not require the knowledge of screening threshold values that are applied for sample categorization after applying the Net Count Calculation (NCC) analysis method used currently by the International Data Centre (IDC) of the CTBTO. Our results support that by synthesizing nuclear engineering and deep learning disciplines, experts can accelerate and optimize the review process of background and CTBT-relevant samples by an average accuracy of 92% and 98% respectively. Speaker: Ms Sepideh A. Azimi (Amirkabir University of Technology (AUT), Tehran, Iran) • 16:05 Markov Chain Monte Carlo Estimate of Origin Error for Seismic, Hydroacoustic, Infrasound Events in NET-VISA 15m NET-VISA is a Physics-Based Generative Model of global scale seismology. The model includes a description of the generation of events which include under-water and atmospheric events, the propagation of waveform energy from the events in multiple phases, and the detection or mis-detection of these phases at the network of stations maintained by the International Monitoring System (IMS) as well as a model of noise processes at these stations. The model and its associated inference algorithm has been deployed by the International Data Center (IDC) to generate a bulletin of events known as VSEL3. This bulletin is currently being used by the analysts to generate the LEB bulletin and in future it is planned to replace the current GA-based SEL3 bulletin with VSEL3. The current version of the inference algorithm relies on the existing IDC libraries to compute the error/coverage ellipse of events. In this work we have added a new module to directly use the NET-VISA model to estimate the 90% confidence ellipse. We describe the details of the Markov Chain Monte Carlo (MCMC) estimation and demonstrate on a study of ground truth events from the International Seismological Center (ISC) that the new confidence ellipses are more accurate. Speaker: Mr Nimar Arora (Bayesian Logic, CA, USA) • 16:20 Emulation of seismic-phase travel times using the Deep Learning Travel Time (DeLTTa) method 15m Deep Learning Travel Time (DeLTTa) is a deep-learning method and computer code for emulating seismic-phase travel times that are based on a 3-dimensional (3D) Earth model. Greater accuracy of travel time predictions using a 3D Earth model are known to reduce the bias of event location estimates and improve the process of associating detections to events. However, practical use of 3D models is challenged by slow computational speed and the unwieldiness of pre-computed lookup tables. DeLTTa trains a deep-learning network using pre-computed travel times, resulting in a compact and computationally fast way to approximate travel times based on a 3D Earth model. DeLTTa is trained using approximately 850 million P-wave travel times based on the LLNL-G3D-JPS model from randomly sampled event locations to 10,393 global seismic stations. After training, the machine-learning computer code is approximately 10 Mbytes in size and travel times are computed in approximately ten micro-seconds on a single CPU. Currently achieved prediction accuracy is approximately ½ second at the 2-sigma level, which is similar to the inherent accuracy of the 3-D model. With additional development, DeLTTa will enable easy use of 3-D models in routine seismological processing and analysis. Speaker: Mr Stephen Myers (Lawrence Livermore National Laboratory (LLNL), Livermore, CA, USA) • 16:35 Identification of repeating seismic events using non-linear dimensionality reduction 15m In this work, we develop an algorithm for automatic identification of repeating seismic events such as aftershocks and mine explosions. Identification of such events will help to improve the quality of automatic bulletins and to lighten the analysts’ burden. The algorithm constructs a low-dimensional representation of the examined data by using a variant of a non-linear dimensionality reduction algorithm named diffusion maps. The proposed methods begin with a pre-processing stage in which a time–frequency representation is extracted from each seismogram while capturing common properties of seismic events and overcoming magnitude differences. Then diffusion maps are used in order to construct a low-dimensional model of the original data. This enables to split the data into one cluster that contains the repeating events and another cluster that holds of the other processed waveforms, which are not related to the examined events of interest. The algorithm’s performance is demonstrated on several seismic data sets that were recorded at IMS stations. In particular, at the IMS station EIL we identify arrivals that were caused by the blasts at the nearby Eshidiya mine in Jordan. Identification and masking of such arrivals should reduce the number of false associations in the automatic bulletins. Speaker: Mr Yuri Bregman (Soreq Nuclear Research Center, Yavne, Israel) • 16:50 Using machine learning to detect and characterize long-range infrasound signals from high explosives 15m The International Monitoring System (IMS) infrasound network is well positioned to record atmospheric nuclear explosions, but algorithmically classifying and characterizing these events is challenging. Difficulties stem from the variable and dynamic atmosphere that modulates acoustic transients at regional to global distances. Machine learning (ML) is well suited to classify infrasound activity but generally requires large training datasets. However, data from the relatively few large chemical explosions and sparse global infrasound network are insufficient to train a ML model given how complex and dynamic the atmosphere is at global scales. Instead, we propose a physics-based data augmentation method to produce an entirely synthetic training dataset. Realistic source time functions are generated and propagated through modeled atmospheres out to several hundred kilometers, thus producing a catalog of synthetic events. These data are then used to train a time convolutional neural network (TCN) that classifies explosions and background noise. We show the TCN not only identifies modeled events but is also effective at detecting and characterizing real world explosive transients, including those from the Humming Roadrunner experiments. This work was supported by the Nuclear Arms Control Technology (NACT) Program at Defense Threat Reduction Agency (DTRA). Approved for public release; Distribution is unlimited. Speaker: Mr Alex Witsil (University of Alaska Fairbanks, Fairbanks, AK, USA) • 17:05 Concluding remarks 10m • 15:45 16:45 The 25th anniversary for opening the CTBT for signature: invited talk on Radionuclide technologies: Invited 25th anniversary talk Location 1 (Online) ### Location 1 #### Online • 15:45 The IMS radionuclide network- a unique machine not yet fully exploited 1h The IMS Network of 80 particulate and 40 radioxenon measurement systems is one of its kind in several ways. The global coverage combined with high time resolution contributes to a unique, steadily growing data set available to all CTBT member states. The requirements of the verification regime, formulated more than 25 years ago, prompted the development of new measurement technologies, such as automated particulate samplers and radioxenon systems. The area of radioxenon detection in particular got a considerable boost, and still remains a very active research area. However, I believe we just got started on the journey towards an even more effective verification regime. Besides describing the development of the past 25 years, I will try to look into the future and discuss a few topics that I believe will be important in the years to come. The development has so far mainly been focused on the individual measurement systems, achieving high measurement sensitivity with high reliability. Less effort has been put on optimizing the network as a whole, with the goal to maximize the combined capability to detect, locate and characterize release sources. I am convinced that by viewing the network as a single measurement system, many improvements still can be made, both with respect to measurements as well as data analysis. Another important remaining task is to identify as many background sources as possible. There are many unexplained detections in the network, and understanding the causes for these is absolutely crucial to the CTBT verification regime. Speaker: Mr Anders Ringbom (Swedish Defence Research Agency (FOI),Stockholm, Sweden) • 16:45 17:15 Series of talks on 25 years of CTBT: Atmospheric Transport Modeling (ATM): Special talk Location 1 (Online) ### Location 1 #### Online • 16:45 Advancements in Atmospheric Transport Modelling (ATM) at the CTBTO PTS during the past two decades and plans for the future. 30m CTBT monitoring for nuclear explosions is based on detection of waveform signals and the related event localization and on detection of traces of treaty-relevant radioisotopes in the atmosphere. However, 25 years ago it was a challenge to obtain a clear link between a seismic event and a series of radionuclide detections. This was changed when the proper Atmospheric Transport Modelling (ATM) system with special postprocessing routines was implemented and the relevant expertise built up. The effectiveness was demonstrated by providing ATM support during events of special interest like the Fukushima accident and the nuclear tests announced by the DPRK. The lessons learnt triggered enhancements. For example, the ATM support during the first DPRK event in 2006 led to the extension of backward trajectories from 6 to 14 days. More recent enhancements include an increase of spatial resolution from 1 degree to 0.5 degree and of time resolution from 3 hours to 1 hour. PTS aims at developing a world-class ATM system and takes all opportunities to validate it against systems from other major ATM centres like participation in multi-model exercises called ATM Challenge. This presentation also addresses the plans for the next years and vision for the longer term. Speaker: Ms Jolanta Kusmierczyk-Michulec (CTBTO Preparatory Commission, Vienna, Austria) • 17:15 18:15 Event 2 - Resilience of the CTBT monitoring regime: Event Stage 3 (Online) ### Stage 3 #### Online Convener: Ms Stefka Stefanova (CTBTO Preparatory Commission, Vienna, Austria) • 17:15 Event 2 on Resilience of the CTBT monitoring regime, including lessons learned from the COVID-19 pandemic crisis 1h The COVID-19 pandemic is a major topic of interest for the SnT2021. The global nature of it produced a resilience test for many, and in particular for a global monitoring system, such as the CTBTO’s, that relies on continuous data gathering, transmission and analysis. The objective of this series of two events is to provide the audience with pertinent case histories and lessons learned from IMS stations e.g. during O&M activities, station upgrades or logistics challenges, faced by the station operators and PTS during the restrictions imposed by COVID-19. Topics presented in Event 2 are (i) the basis on which INPRES, Argentina, was able to continue providing its essential services during the COVID-19 pandemic and how the face-to-face work and the use of Software for Telework and new work standards affected some PLCA/PS01 station metrics, (ii) how the COVID-19 restrictions affected the operation and maintenance of the IMS infrasound and radionuclide stations operated in Argentina by ARN, (iii) the technical and logistical challenges faced and overcome by INOCAR, Ecuador, while operating and maintaining IS20 and RN24 in Galapagos during the COVID-19 pandemic. (iv) A demonstration of how technical, environmental, logistical and administrative challenges faced at IS35 infrasound station, Namibia, in conjunction with COVID-19 lockdowns, were overcome to bring the station back to life and return it to mission capability, and (v) examples presented by CTBTO IDC/OPS of restrictions imposed by the COVID-19 pandemic that affected the resolution of operational issues with impact on timely data availability/data quality, together with contingency measures employed. Speaker: Ms Stefka Stefanova (CTBTO Preparatory Commission, Vienna, Austria) • 17:15 18:45 Panel discussion on Innovation affecting CTBT – pertinent to IMS monitoring system (sensors): Panel discussion Location 1 (Online) ### Location 1 #### Online • 17:15 Innovation affecting CTBT: pertinent to IMS monitoring system (sensors) 1h 30m The CTBT IMS employs four monitoring technologies: seismology, infrasound, hydroacoustics and radionuclide (both particulate and noble gas). It is vital that the PTS stays abreast of new developments related to all sensor types to maintain its high-performance level, and network sustainability, in order to safeguard and improve the Treaty Verification capability. This panel will discuss new generation sensors that may already be available, and innovative efforts for future developments. Potential areas of discussion are networks of infrasound sensors, combination of rotational and directional seismic sensors, modular design hydroacoustic hydrophone stations, SMART underwater cables and sensors, fibre-optic seismometers and hydrophones, improved concepts for particulate radionuclide stations, new generation of noble gas stations. Speaker: Ms Nurcan Meral Ozel (CTBTO Preparatory Commission, Vienna, Austria) • 17:30 18:30 T2.5 - Historical Data from Nuclear Test Monitoring: Oral session Stage 2 (Online) ### Stage 2 #### Online Convener: Mr Martin B. Kalinowski (CTBTO Preparatory Commission, Vienna, Austria) • 17:30 Session introduction 5m • 17:35 Analysis Of Historical Seismograms Of Central Asia Stations To Precise The Parameters Of Nuclear Tests At Lop Nor Test Site 15m The Lop Nor Test Site is located in Xinjiang Province in the Peoples Republic of China, about 600 km away of Kazakhstan. From 1964-1996, there were 47 nuclear tests, including 3 surface, 19 atmospheric, and 25 underground. During this time, the USSR operated monitoring networks of sensitive seismic stations having both analog and digital instruments. A seismic catalog and bulletin was created using the archived seismograms of Central Asian stations located in Kazakhstan, Kyrgyzstan, and Russia (epicentral distance 700-2500 km). In total, 800 seismograms of 41 explosions were processed. Using satellite imagery, epicenters were précised for all explosions, including atmospheric and small underground tests. The mb, regional mpv and MLV magnitudes, and energy class K were calculated. The waveforms of Lop Nor air and surface explosions were analyzed using microbarograph records from the Talgar Observatory in Kazakhstan. For several small explosions, locations were précised, dynamic parameters of seismic and infrasound records were analyzed, and origin times were calculated for the first time. As a result, the précised catalogue of nuclear explosions conducted at Lop Nor Test Site was compiled. Many of the explosions can be used as Ground Truth events to construct the regional travel-time curves and for stations calibration. Speaker: Mr Kevin Mackey (Michigan State University (MSU), East Lansing, MI, USA) • 17:50 Using historical data to improve analysis of nuclear testing 15m Films from historic nuclear testing enable new analysis of the shock propagation and buoyant cloud rise with material entrainment, furthering understanding of the time-evolution of the entrained mass. Many late cloud films were captured from at least two positions, enabling accurate characterization of the cloud development and trajectory. A generalized framework is developed to capture the similarity of nuclear debris cloud formation for detonations with similar scaled heights of burst. The nuclear debris cloud regimes are defined based on debris cloud behavior observed in a dry, dusty environment with loose, easily lofted surface material and can be used to improve dispersion models. As new information on how expected material entrainment and mixing is affected by the surrounding environment becomes available, adjustments to the regime height-of-burst ranges are easy to adopt. Both fast-running fallout codes and higher-fidelity cloud-rise and fallout codes need to be validated against existing test data. We present on the use of historical film to provide many types of data to validate and improve models of late cloud behavior. Combining such data with an understanding of buoyant cloud rise and cloud stabilization informs entrainment including the total mass of entrained materials. Speaker: Ms Stephanie Neuscamman (Lawrence Livermore National Laboratory (LLNL), Livermore, CA, USA) • 18:05 Overview on historic atmospheric radionuclide monitoring data associated with nuclear test explosions conducted between 1964 and 1996 15m A literature review is presented on historic atmospheric radionuclide monitoring data that were associated with nuclear test explosions. It covers reports related to tests conducted between 1964 and 1996. Most of these tests occured in the atmosphere but observation of nuclear debris from venting of underground nuclear tests were also found.The review is limited to off-site monitoring and many observations were done at large distances including several tests that were detected on multiple locations on the same hemisphere. This data set could be of value for validating methods based on atmospheric transport simulations with the objective of identifying 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, Vienna, Austria) • 18:20 Concluding remarks 10m • 18:15 19:15 CTBTO Youth Group: CTBTO Youth Group SnT 2021 Fireside Chats 1 Stage 3 (WebEx) ### Stage 3 #### WebEx • 18:15 CTBTO Youth Group SnT 2021 Fireside Chats 1 1h Building on the successful practice of the #CYGWebinars, the virtual format of SnT 2021 will benefit from interactive engagement opportunities between CTBTO Youth Group (CYG) members and SnT speakers and high-level guests. These two half-hour virtual Fireside Chats will feature brief presentations on global topics of interest by prominent SnT speakers and high-level guests, followed by an informal interactive discussion with CYGs. These webinars will encourage young people to engage with experts and generate interest in the wide variety of topics and presentations featured at the Conference. The first Fireside Chat will be moderated by Mr Marius Jano (CTBTO Preparatory Commission, Vienna, Austria). The second Fireside Chat will be moderated by Ms Sneha Nair (CTBTO Preparatory Commission, Vienna, Austria). Speakers: • Professor Tracey Rogers, Marine Ecologist, University of New South Wales Sydney • Ms. Zainab Azim, Co-Founder of G.I.V.E and Youngest Member of Virgin Galactic's Future Astronaut Program • 18:30 19:00 Series of talks on 25 years of CTBT: Radionuclide Technologies: Special talk Stage 2 (Online) ### Stage 2 #### Online Convener: Mr Martin B. Kalinowski (CTBTO Preparatory Commission, Vienna, Austria) • 18:30 Review and outlook of radionuclide screening methods for discriminating nuclear explosion signals from normal radioactivity background in the atmosphere 30m For the International Monitoring System (IMS) to be effective, it is vital that nuclear explosion signals can be distinguished from natural and man-made radioactivity in the atmosphere. The International Data Centre (IDC) applies standard event screening criteria, with the objective of characterizing, highlighting, and thereby screening out, events considered to be consistent with natural phenomena or non-nuclear, man-made phenomena. This presentation looks back to the initial understanding of possible screening methods in the early years of CTBT negotiations, summarizes the development of the categorization schemes and screening flags applied in the IDC reports for each particulate and noble gas sample, and reviews new proposals and open issues for discriminating nuclear explosion signals from normal radioactivity background in the atmosphere. There is still high need and ample room for enhancing radionuclide screening methodologies. This presentation sketches out what methods that were already demonstrated can be enhanced and implemented in the coming years, which novel methods appear promising to be developed and it creates a vision of highly effective screening for the longer future. Speaker: Mr Theodore Bowyer (Pacific Northwest National Laboratory (PNNL), Richland, WA, USA) • Wednesday, 30 June • 09:00 12:00 T2.1 e-poster session: T2.1 - Characterization of Treaty-Relevant Events Online #### Online T2.1 Conveners: Mr Boxue Liu (CTBTO Preparatory Commission, Vienna, Austria) , Mr Mario Zampolli (CTBTO Preparatory Commission, Vienna, Austria) • 09:00 12:00 T2.1 e-poster session: e-poster session - T2.1 - Characterization of Treaty-Relevant Events Online #### Online T2.1 Conveners: Mr Boxue Liu (CTBTO Preparatory Commission, Vienna, Austria) , Mr Mario Zampolli (CTBTO Preparatory Commission, Vienna, Austria) • 09:00 Lessons from OSI field tests and exercises for the development of contextualized geophysical survey strategies and methods 15m The sole purpose of an OSI as specified in Article IV of the Treaty is “to clarify whether a nuclear weapon test explosion or any other nuclear explosion has been carried out” and “to gather any facts which might assist in identifying any possible violator.” OSIs are to provide this clarity through the collection of information and the detection of relevant observables within the Inspection Area. For this, the inspection team may undertake visual observations and use imaging, radionuclide and geophysical OSI techniques. This presentation demonstrates how, on the example of an OSI, the objectives of a particular field mission will determine the selection of the most appropriate geophysical survey strategies and methods. Actual data collected during several OSI field tests and exercises, which presented underground nuclear explosion scenarios, will be shown and discussed in the context of the rationale and timelines of different field mission objectives. Particular emphasis will be placed on how the integrated use of various inspection techniques may contribute to the characterisation of a site. In this context, the importance of accuracy and the inherent uncertainties of the application of geophysical techniques will be demonstrated as well. Speaker: Mr Sam Toon (Arete Services Ltd, Newcastle, United Kingdom) • 09:15 Discrimination of seismic events (2006 to 2020) in North Korea using P/Lg amplitude ratios from regional stations and a bivariate discriminant function 15m Two events of magnitude ($m_{b}\$) 3.6-3.8 occurred in southern North Korea (NK) on 27 June 2019 and 11 May 2020. Although these events were located about 330-400 km from the known nuclear test site, the fact that they occurred within the territory of NK, a country with a recent history of underground nuclear tests, made them events of interest. We used P/Lg ratios from regional stations to categorize seismic events that occurred in NK from 2006 to May 2020, including the two recent events, the six declared NK nuclear tests, and the cavity collapse and triggered earthquakes that followed the 3 September 2017 nuclear explosion. We were able to separate the cavity collapse from the population of nuclear explosions. However, the distinction between the earthquakes and the cavity collapse is ambiguous. We used cross-spectral Pg/Lg and Pn/Lg ratios jointly in a quadratic discriminant function and successfully categorized the six declared nuclear tests and the triggered earthquakes that followed the September 2017 explosion. Our analyses also confirm that the recent southern events are both tectonic earthquakes that occurred naturally.

Speaker: Mr Rigobert Tibi (Sandia National Laboratories (SNL), Albuquerque, NM, USA)
• 09:30
Event Analysis of CTBT Relevant Radionuclides Detected in the Nordic Region 2020 15m

A series of measurements of multiple anomalous treaty relevant radionuclides at several measurement stations in Sweden and Finland, including the Stockholm aerosol sampler (SEP63) in the International Monitoring System (IMS), occurred in the summer of 2020. The cause and source of these radionuclides is still unknown. The laboratory re-measurement of the split IMS sample revealed that one-half of the split sample contained the entirety of the anthropogenic radioactivity - a high degree of sample inhomogeneity due to hot aerosol particles. Using the IMS results and by performing some advanced laboratory coincident measurement techniques, an international, multidisciplinary team started to unravel the details on the nature of this event while also demonstrating the verification benefits of adopting new sample analysis techniques.

• 09:45
Forensic Event Analyses at the Turkish NDC 15m

During the year 2020, apart from the global pandemic, there have been several global incidents that were recorded by IMS stations. As Turkish NDC, we have selected three of these events to be analyzed. The first event is the fragmentation of a meteorite/bolide on 27 May 2020 that was observed by many cities over the Northeastern part of Turkey, the second event is the Fireworks factory explosion at the outskirts of Sakarya city of Turkey occurred on July, 3rd and the last event that was analyzed is the explosion of 2.7 kT Ammonium Nitrate at the harbor of Beirut, Lebanon on 4 August 2020. Since all of these events occurred on the surface or the atmosphere, several IMS infrasound stations detected the acoustic pressure changes over great distances. In addition to the IMS infrasound stations, local seismic stations in Turkey recorded the ground vibrations caused by the shock waves of these events. Therefore, we were able to make an event analysis using fusion of both technologies to test not only our NDC's capabilities but also the products and tools that were provided by CTBTO. Our final analysis results will be presented at SnT 2021.

Speaker: Korhan Umut Semin (Bogazici University, Istanbul, Turkey)
• 10:00
Data-based kernel density equations for probability distributions of CTBT-relevant radioxenon isotopes at IMS stations in normal background from nuclear facilities and as simulated from underground nuclear explosions 15m

The objective of this study is to apply the kernel density (KD) approach to generate and investigate probability distributions of isotopic ratios for radioxenon releases from certain types of sources. KD equations for nuclear facility releases are derived from the data set of the radioxenon emission inventory of all nuclear power plants and all nuclear research reactors, as well as selected medical isotope production facilities in the calendar year 2014. Analytical equations for the releases from assumed underground nuclear explosions are obtained using Bateman equations for simple scenarios of prompt and delayed releases from underground nuclear explosions with in-growth and decay or alternatively with complete fractionation at time zero after the nuclear fission event. For both types of sources, KD equations will be linked with isotopic ratio calculations that connect source and receiver. The goal is to create probability density functions that could be applied e.g. with a Bayesian method to determine the probability whether an IMS observation could possibly be caused by a nuclear explosion.

Speaker: Mr Martin B. Kalinowski (CTBTO Preparatory Commission, Vienna, Austria)
• 10:15
Improving the Resolution of the Isotropic Seismic Moment Tensor using Rotational Ground Motions 15m

Seismic moment tensors provide information not only about the geometry of a seismic source (tectonic – DC – part) but also with non-tectonic information such as volume changes (isotropic – ISO – part). This feature is crucial to discriminate explosive sources from others, which can hint to a nuclear test. However, that part is often not well resolved by standard methods. Measuring rotational ground motions might help to obtain more reliable results.
Six components of ground motion are needed to entirely describe the seismic wave-field, three translational and three rotational. Just recently, portable rotation sensors dedicated for seismological applications are available. In previous studies, we show that by inverting both ground motions together, the resolution of the moment tensor can be improved significantly.
In a synthetic set-up for the Korean peninsula we analysed the 2013 nuclear test of the Democratic People’s Republic of Korea. Applying a Bayesian inversion method, we tested three frequency bands. We also tested the inversion with Green‘s functions based on one- and three-dimensional structural models. The reliability of the source mechanism benefits form both, the three-dimensional structure and rotations, even more in the higher frequency ranges. Thus, also the reliability of the ISO part is increased.

Speaker: Ms Stefanie Donner (Federal Institute for Geosciences and Natural Resources (BGR), Hannover, Germany)
• 10:30
UK National Data Centre: Radionuclide Event Analysis 15m

The UK National Data Centre (NDC) operates a series of custom-developed software tools for the automatic processing, analysis, archiving and interpretation of radionuclide (RN) data from the International Monitoring System (IMS). The tools include an RN Pipeline for the analysis of radionuclide data (noble gas and particulate), and a series of simulation pipelines to provide accompanying atmospheric transport modelling (ATM) data. The ATM products are triggered on the identification of an ‘RN detection event’, which can include radioxenon plumes or ‘high-priority’ detections. An overview of the toolset is presented, along with case-studies using interesting RN detections from recent years, such as particulate detections at SEP63 and RUP61 during 2020.

Speaker: Mr Matthew Goodwin (AWE Aldermaston, Reading, United Kingdom)
• 10:45
Atmospheric Transport Modelling for potential releases and detections possibly connected with announced DPRK nuclear tests 15m

Various techniques of Atmospheric Transport Modelling were applied after announced DPRK nuclear tests in order to support the analysis of potentially connected radionuclide detections. Forward dispersion forecasts from the test-site predicted potentially affected IMS stations; forward ATM for known background sources assessed their potential contribution to measured concentrations.
In case of detections, backward ATM has shown consistency with certain emitter locations and identified coincident source regions for multiple detections.
As we think that DPRK test 2017 could and must have been the last nuclear test at all, the presentation gives a comprehensive overview how ATM supported the analysis of the National Data Centre. Special focus is how potential interference with known background sources had an impact on the assessment. In several cases measurements of releases from nuclear facilities caused ambiguous radioxenon detections in the aftermath of DPRK tests.
Finally, for two DPRK tests (2009 and 2016-Sep) it was not possible to identify potentially related radioxenon detections, for two tests there were consistent but not conclusive detections of Xe-133 only (2016-Jan, 2017) and for two tests there were matching isotopic ratios and fitting atmospheric conditions (2006, 2013).

Speaker: J. Ole Ross (Federal Institute for Geosciences and Natural Resources (BGR), Hannover, Germany)
• 11:00
Rapid and automated full seismic source characterization: seismic monitoring application for the North Korean region 15m

Rapid full source characterization is strongly recommended for providing pertinent information after the occurrence of an event of interest such as a nuclear test. Full moment tensor inversion using long-period seismic waveforms recorded at regional distance has shown its relevance for confirming the isotropic component of a seismic source. In order to rapidly determine the full source parameters of events occurring in a region of interest, an automated grid-search moment tensor approach can be proposed. Here, we show that such method called GRiD MT reveals the main parameters of any events with magnitude above 3.5 within a few minutes: detection, origin time, location, moment magnitude and mechanism. We demonstrate its interest for seismic monitoring when implemented over the North Korean region using only a limited number of seismic stations. Correct identification of all past North Korean nuclear tests (including the smallest one in 2006) is rapidly obtained within an easy-to-use algorithm for a seismic analyst. Lastly, GRiD MT can be used for the monitoring of small to larger tectonic events, and is currently being tested and implemented for multiple objectives at the French National Data Center: nuclear test monitoring, earthquake monitoring, and tsunami warning.

Speaker: Ms Aurelie Guilhem Trilla (Commissariat à l’énergie atomique et aux énergies alternatives (CEA), France)
• 11:15
Simulations of the long-term evolution of Ar-39 produced in an underground nuclear explosion 15m

Measurements of gas collected from locations surrounding historic underground nuclear tests have identified that Ar-39 produced during a nuclear explosion can remain in the subsurface decades after the event occurred. As an activation product produced by the interaction of neutrons with geologic potassium, Ar-39 is produced in significant quantities in almost any underground nuclear explosion. With a half-life of 269 years, the primary loss mechanism for Ar-39 over time is dilution in the atmosphere or the geology surrounding the event. In order to better understand how the transport of Ar-39 affects its viability as a long-lived underground nuclear explosion signature, a series of simulations were performed of an initially pressure-driven Ar-39 source with varying depth and geology type surrounding the source. The evolution of both Ar-37 and Ar-39 was modeled over 30 years and the loss to the atmosphere or to dilution in the surroundings was tracked.

Speaker: Mr Justin Lowrey (Pacific Northwest National Laboratory (PNNL), Richland, WA, USA)
• 11:30
Using publicly available non-seismic constraints to estimate the yield of a large explosion in Beirut, Lebanon 15m

A study of a large explosion in Beirut, Lebanon, explores the use of non-seismic constraints to supplement the seismic data yield estimates. The explosion yield is estimated by fitting overpressure to the equivalent of a 1kT overpressure curve as a function of radius from the explosion ground zero. Overpressure is estimated using explosion damage evaluations from publicly available sources such as aerial photos, movies and press articles. An equivalent yield interval of 0.7-0.9-kT is estimated.

Speaker: Dr Ileana Tibuleac (Air Force Technical Applications Center (AFTAC), FL, USA)
• 11:45
An array of noble gas samplers suspended at various heights from light gas-filled balloons hard wired to the ground to bolster the efforts of an On-Site Inspection team 15m

The On-Site Inspection (OSI) Team shall converge to the possible test location applying various permitted inspection techniques using approved equipment within /set timeframe (technical & political significance). OSI relevant noble gases such as Argon and Xenon from the potential test(s) (underground) may reach the atmosphere through venting and/or atmospheric pumping (depending upon local geology). These gases are denser than the earth’s atmosphere at sea level and are terrain hugging in nature. The lift (elevation) & movement (horizon) are primarily caused by wind. An array of portable noble gas samplers covering elevation(vertical) and azimuth(horizon) may be used to increase the probability of detection. The array design for sampling of OSI relevant noble gases depends upon :
• Properties of OSI relevant noble gases(Known)
• The distance between point of release (vent) and sampler (Unknown)
• The Meteorological Data (Probabilistic weather forecasting)
This paper discusses the design of an array (no of elements, distance between elements) and the placement.
Probabilistic assessment of 8760 hourly sampled/historical weather data involving atmospheric weather modelling (like Gaussian puff-plume and Lagrangian particle model) to understand the design and performance optimization (of arrays) is considered.

Speaker: Mr Ankit Mishra (Ministry of Science & Technology, New Dehli, India)
• 11:45
Connecting underground nuclear explosion gas-release ranges as aggregated from a set of scenarios with IMS radioxenon observations for evaluating isotopic activity ratios as indicators of a nuclear test 15m

Isotopic activity ratios of radioxenon measured in IMS noble gas samples are routinely obtained that might indicate a gas release from an underground nuclear test, although actually caused by atmospheric emissions from nuclear facilities. A robust method is required that tests the isotopic activity ratios of samples of special interest against a set of all relevant release scenarios that could possibly explain the source. This presentation treats nuclear explosions as the source. The method presented here combines the two ends of the lifetime of radioxenon isotopes and their activity ratios. One end is the radioisotope generation by a nuclear explosion, the other end is their measurement in IMS samples. Mathematical modelling is used to create the relationship between both ends. Recent research results on the source mechanisms including in-growth and decay, cavity-melt fractionation and seepage of cavity gases are used to develop best-estimate input source terms as well as minimum and maximum activity ratio boundaries as a function of time. The ratios in the IMS sample are reconstructed as a function of the time of release into the atmosphere and the sampling time. The output is a score for the consistency of a set of scenarios with the observation.

Speaker: Mr Martin B. Kalinowski (CTBTO Preparatory Commission, Vienna, Austria)
• 11:45
Nuclear Debris Characterization by Fission Isotope Assessment 15m

Radionuclide isotopic composition analysis is an important and reliable tool for determination of the artificial radionuclide source. As each anthropogenic emission could be characterized by its own unique radionuclide composition, these „fingerprints” make it possible to determine the evidence of radionuclide contamination source. Gamma spectrometric measurements were performed with the state-of-the-art “Ortec” alpha spectrometer and gamma spectra were recorded by SILENA gamma-spectrometric system with an HPGe coaxial detector. Radionuclide isotopic ratios were measured by a high resolution sector field mass spectrometer combined with a high sensitivity APEX sample introduction system. Elevated 137Cs/239,240Pu, 238Pu/239,240Pu, 240Pu/239Pu isotopic “finger print” values reliably reveal a nuclear event and assess its source by fusing these values with atmospheric transport modelling. The report discusses the areas of uneven “hot” particle deposition and large, vast “hot” spots.

Speaker: Mr Andrius Puzas (Center for Physical Sciences and Technology, Vilnius, Lithuania)
• 11:45
Three-dimensional space analysis of radioxenon isotopic activity ratios for characterizing a nuclear event in comparison to civilian releases from fission and activation 15m

This study on the nuclear release timing aims analysing radioxenon isotopic activity ratios in three-dimensional space. The methodological approach and the characterization of the 3D usability threshold considered in this study were presented during SnT2019 and INGE2019. This presentation focuses on comparison to civilian sources from fission and activation.
Obviously three isotopes are less likely to be detected simultaneously than two isotopes are. However, if three isotopes are available, making use of all three together offers a much more powerful analysis mechanism than with only two isotopes. In the three-dimensional space the analysis of timing and event screening can be separated. A time-independent screening can be achieved through the projection along the decay axis and the time. In this projection, event characterization can be achieved without knowledge about the time of the release from the source. The time-independent screening is most useful for CTBT monitoring purposes since the time of origin of a remote detection is in general not known. In addition, under favourable conditions, the event origin time can also be determined irrespective of the source scenario by projecting the isotopic ratios on the decay axis and scale it in units of time.

Speakers: Mr Kassoum Yamba (Centre National pour la Recherche Scientifique et Technique (CNRST), Ouagadougou, Burkina Faso) , Mr Martin B. Kalinowski (CTBTO Preparatory Commission, Vienna, Austria)
• 09:00 12:00
T2.2 e-poster session: T2.2 - Challenges of On-Site Inspection Online

#### Online

T2.2

Conveners: Mr Julius Kozma (CTBTO Preparatory Commission, Vienna, Austria) , Mr Andrew Collinson (CTBTO Preparatory Commission, Vienna, Austria)
• 09:00 12:00
T2.2 e-poster session: e-poster session - T2.2 - Challenges of On-Site Inspection

T2.2

Convener: Mr Julius Kozma (CTBTO Preparatory Commission, Vienna, Austria)
• 09:00
Application of visualized 3-D simulation platform to OSI operation management and decision making support 15m

An OSI could be conducted anywhere. Due to the concept of the comprehensive nuclear test ban, an OSI inspection area could be in an extremely challenging environment. A simulation platform could be a solution both from the perspective of health and safety and mission efficiency. This work would propose a compact transportable visualized 3-D simulation platform to provide decision making and management support to OSI operations. Based on personal and environmental interactive virtual reality technology, it would quickly create a virtual reality inspection area environment utilizing treaty-agreed commercial remote sensing images and terrain data. Different terrains and environments could be simulated and visualized, such as mountainous areas, the Gobi Desert, water-based areas and inhabited towns under different lighting and weather conditions. The base of operations setup and routine management, health and safety management, contamination area marking, managed access area marking, mission estimation, sub-team daily mission planning, inspection routes planning, search area management, ground inspection and overflight simulation could be achieved. Holographic visualization could also be achieved through holographic goggles to realize immersive visualization. The system is compatible with popular international GIS platforms. During overflight simulations, an external joystick can be used to achieve a more vivid simulation effect. A touch screen has been used for better handling.

Speaker: Mr Peng Li (Hope Investment Development Corp. Ltd., Beijing, China)
• 09:15
Unfolding Directional Aerial Radiation Survey Maps to enable Extrapolation and Improved Precision 15m

Gamma spectroscopy measurements are a key component of an on-site inspection conducted under the Comprehensive-Nuclear-Test-Ban-Treaty. Radiometric aerial survey has proven to be an efficient way to cover large areas, however the spatial distributions of features smaller than the survey altitude are smeared out and their radioactivity concentration is underestimated. Moreover, the inspected state party may declare multiple restricted access sites over which the aerial survey may not be able to fly. In previous work presented in this conference series we have shown how multi-crystal direction-capable or imaging gamma detectors can reconstruct radioactivity distributions in a restricted access site from vantage points on its perimeter. In this work, we present a new method to unfold the measurement making use of Monte Carlo generated response functions in an iterative minimization to extract the true underlying radioactivity distribution within uncertainties. By requiring the solution be consistent with the measurement from every crystal sub-detector involved in the survey simultaneously, this method greatly improves spatial precision and the distance over which extrapolation is valid. Most importantly, the method provides the significance of the observation of radioactivity in certain areas, and gives an upper limit on the amount of allowed radioactivity in other areas.

• 09:30
Operations Support Centre during Preparations for an On-Site Inspection 15m

The Operations Support Centre (OSC) is a crucial element for effective preparation for an on-site inspection (OSI); its organization and proper functioning directly impact the degree of inspection team preparedness before departing for the inspected State Party. The OSC will be activated within a couple of hours after the DG has received a request for an OSI, and it must immediately become operational. That requires a sound concept, a tested organizational approach, adequate infrastructure, clear and user-friendly procedures, and trained staff from all units of the Technical Secretariat.
The OSC concept and related operating procedures have evolved over the time. The most recent update reflected the experience from the 2014 integrated field exercise and the commissioning of the new CTBT Operations Centre (COPC) at the PTS headquarters (Ref. SnT2019-T4.4-P13), which is a potential deployment location for an ad hoc OSI OSC at the Vienna International Centre. It was tested during the Build-Up Exercise on the OSI launch phase (BUE-L) in November 2019.
This poster explains the updated concept and organization of the OSI OSC as an ad hoc part of the COPC, illustrates the infrastructure, and summarizes relevant aspects of BUE-L.

Speaker: Mr Julius Kozma (CTBTO Preparatory Commission, Vienna, Austria)
• 09:45
Radiation hardened RFID solution to OSI samples Chain-of-Custody 15m

CTBT treaty clarifies that “The DG shall have the primary responsibility for the security, integrity and preservation of samples. The DG shall, in any case, establish a stringent regime governing the collection, handling, transport and analysis of samples”. This work is dedicated to the engineering application of IOT/RFID technology to the CTBT technical framework and real OSI scenarios and to provide practical engineering solution. Radiation hardened design was utilized for the first time to develop OSI scenario oriented RFID chips to meet with normal function requirements under nuclear radiation environment while handling OSI samples. Dual-RFID-label mechanism was invented for the first time to realize both tamper evident and Chain-of-Custody solution to OSI samples. Customized containers design of different shapes and materials was also utilized to meet with the requirements of collection, handling, transportation and analysis of all forms of samples including water, soil, vegetation, noble gas. Suggested application solution of global coverage IOT Nano-satellite constellation could be utilized to strengthen the overall Chain-of-Custody concept and in-real-time tracking of OSI samples during transportation and off-site analysis.

Speaker: Mr Peng Li (Hope investment Development Corp. Ltd., Beijing, China)
• 10:00
COVID-19 Protocols, preventive measures, and recommendations for On-Site Inspection. 15m

COVID-19 is an infectious disease caused by the new coronavirus SARS-CoV2, recently discovered and for which there was no history of human pathologies. Currently COVID-19 is a pandemic that affects many countries around the world.
The objective of this presentation is to apply safe work protocols to protect people from any situation that implies a potential risk of contagion with COVID-19, during an On-Site Inspection or Exercise.
Ensure the health and psychophysical integrity of the OSI Inspection team, representatives of the Inspected State Party and third parties linked to the services provided to the On-site inspection through the implementation of preventive measures and recommendations that guarantee safe work procedures.

Speaker: Mr Marcelo Alejandro Fernandez (Autoridad Regulatoria Nuclear (ARN), Buenos Aires, Argentina)
• 10:45
Update on the OSI airborne techniques simulator 15m

The development of an airborne physical simulator to support the development and testing of airborne OSI equipment configurations as well as facilitating ground-based training for airborne operations was reported at SnT2019. This paper provides an update to the project, summarises the difficulties of transforming a dilapidated airframe into a multi-purpose structure and describes its commissioning. The interior of an Mi-2 helicopter has been completely transformed and now provides a realistic and flexible configuration enabling simulations of different airframe types. All original cabling and unnecessary elements have been removed while the cockpit, windows and interior lining have been enhanced but still retain the feel of a military helicopter. The exterior of the airframe has been repaired and repainted with hardpoints added to mimic a range of different airframes. These hardpoints allow training on the installation of external equipment such as laser range finders and radar altimeters. Real life scale 3D printed versions of airborne equipment are now available for use in the simulator allowing testing and training on realistic alternatives to the real items.

Speakers: Mr Aled Rowlands (CTBTO Preparatory Commission, Vienna, Austria) , Mr Kornél Szalay (NAIK Institute of Agricultural Engineering, Gödöllő, Hungary)
• 11:00
A Compact Portable Cognitive Satellite Communication System for OSI 15m

In principle, OSI could be conducted anywhere on the earth. Communication is mission critical for OSI. 10 years have passed since the last Directed Exercises of OSI communication in Jordan. Some of the communication equipment suggested by the exercise, mostly old fashioned radio communication, would find its restrictions for meeting the practical requirements of OSI. Based on cognitive satellite communication and ad hoc communication networking technologies, this work carried out a study of cognitive satellite communication system for OSI. A compact portable satellite communication prototype VSAT has been developed with high reliable capability achieved by advanced cognitive communication technology. The main specifications are the following: Weight is less than 7 kg including lithium battery, which is suitable for inspectors to carry. Size is 310mm×460mm×60mm with antenna and receiver in an integrated design. Working time is up to 5 hours. Communication speed is up to 256Kbps. By means of working with ad hoc hubs (deployment depending on IA terrains, individual terminals, and commercial encryption, it would provide a reliable communication working environment for IT and IT members, supporting secured communication among IT members, ISP representatives, BoO, CTBTO headquarters and other possible parties.

Speaker: Mr Peng Li (Hope investment Development Corp. Ltd., Beijing, China)
• 11:15
EIMO - the equipment and instrumentation management system for OSI 15m

At SnT 2019 the development of an On-Site Inspection system for managing OSI equipment and software was reported. The system, now called, EIMO – the equipment and instrumentation management system for OSI – has been further expanded and rolled out as a production system. The custom browser-based system is used for recording and tracking both OSI inspection gathering and support equipment. This encompasses the key task of setting maintenance plans and recording all maintenance activities undertaken at an item or system level. EIMO holds definitive information on OSI inspection and support equipment. As well as facilitating work at the TeST Centre, EIMO was also used during the Launch Phase element of the OSI Build-up Exercise in November 2019 to generate the equipment list for the OSI mandate.
EIMO has been expanded for use during an OSI. Modified versions of EIMO are available for use at the point of entry to support equipment checking and also in the working and receiving areas at the base of operations to support the management of equipment configurations. EIMO is available to the relevant versions of GIMO to facilitate the planning of missions and field teams as part of the Inspection Team Functionality cycle.

Speaker: Mr Aled Rowlands (CTBTO Preparatory Commission, Vienna, Austria)
• 11:30
Combined Ground Magnetic and Very Low Frequency Electromagnetic (VLF-EM) Investigations for Gold Exploration around Ihale in Bunnu-Kabba Area of Kogi, north-central Nigeria 15m

This study combines ground magnetic and Very Low Frequency Electromagnetic (VLF-EM) geophysical investigation techniques to evaluate the economic potential of mineralized pegmatite veins for gold and associated metallic deposits. Twenty five carefully planned magnetic and VLF-EM profiles, each, were occupied east and west of a reference profile purposively established on an identified mineralized pegmatite vein around Ihale in Bunnu – Kabba area of Kogi, north-central Nigeria. The acquired magnetic data were filtered and transformed to remove regional field effect, cultural noise as well as focus magnetic anomaly peaks over corresponding sources. The measured raw real and raw imaginary components of the EM fields were subjected to Fraser and Karous Hjelt filtering to remove harmonic noise, make anomaly amplitudes relate directly to the causative conductors and also generate current density for charactering the subsurface. Seven zones of relatively high current density with matching high residual positive magnetic anomalies present closely correlate-able signatures with subsurface response of the reference profile established where local mining activities indicate evidence of gold and associated metallic mineralization. The applied geophysical techniques in this study demonstrate the efficacy of geophysical tools for delineating natural/induced earth structures and artefacts whose identification are valuable in test ban verification.

Speaker: Mr Olawale Osinowo (University of Ibadan, Nigeria)
• 11:45
Commercially used ground penetrating radar’s customized application to OSI 15m

According to CTBT treaty, Ground Penetrating Radar (GPR), together with magnetic and gravitational field mapping and electrical conductivity measurements, are non-destructive geophysical detection technology which can achieve effective detection of OSI anomalies or artifacts underground. As a matter of fact, GPRs have been commercially widely used for decades to conduct safety inspection of underground gas pipelines of cities and towns. It has also been commercially widely used to detect caves under the paved roads to avoid any unexpected land subsidence accident. This work is the active result of joint efforts made by experts of OSI and experts of commercial GPR application. Based on the rich experience and data accumulation of underground pipelines and caves detection, customized radar detector design and data processing mechanism suitable for CTBT OSI scenarios has been put forward. According to the requirements of different geological environment, working frequency of radar ranging from 50MHz to 1GHz can be customarily designed, so as to make the GPRs meet with practical requirements of real OSI scenarios. Moreover, the GPRs would be made user-friendly based on Android operating system, with touch screens and blue tooth data communication capability, etc.

Speaker: Mr Peng Li (Hope investment Development Corp. Ltd., Beijing, China)
• 11:45
Geophysical Characterizations of Unconsolidated Sediments for Geotechnical Studies at Bhadrapur Municipality Area of South-east Nepal 15m

Geophysical characterizations of unconsolidated sediments can be correlated with the invasive geotechnical investigations considered as a scientific basis for land use planning and development. In this study, Centerless Circular Array (CCA) having 2 Hz frequency (short period with a circumscribed radius of 2 m) seismometers were used to estimate the subsurface velocity profile, whereas Vertical Electrical Sounding (VES) used to estimate the resistivity of individual layers. Standard Penetration Test (SPT) were used to conduct the field survey for estimating N values. Soil samples were taken for laboratory testing to understand the soil type, water saturation, texture etc. Preliminary result showed that the sediments in Bhadrapur Municipality area which has shear wave (Vs) velocity ranges from 100 to 500 m/s, whereas the resistivity ranges from 20 to 400 ohm-m. Corrected N value for the gravelly sand ranges from 7 to 25 blows whereas for silty sand it ranges from 4 to 10 blows. The shear wave velocity, resistivity and the N value map were prepared. Shear wave velocity and its correlation with N value would be helpful in seismic micro-zonation of the areas where ground motion is considered as an important parameter.

Speaker: Mr Rajendra Prasad Bhandari (Department of Mines and Geology (DMG), Kathmandu, Nepal)
• 11:45
Improving environmental radioactivity monitoring by the use of shielded portable HPGe detector 15m

The ENEA Traceability Laboratory in Bologna utilizes a portable HPGe gamma spectrometer Trans-SPEC-DX-100T for in situ monitoring campaigns and to evaluate the possible presence of radioisotopes in the environment (e.g. waste assay measurements, emergency response, nuclear safeguards inspection).
The instrument is also used in the laboratory to characterize radioisotope concentrations in samples from different sources: ie contaminated environmental soils, food with different radioisotopes absorption rates, nuclear materials.
The gamma monitoring technique is allowed to be used during an On-Site Inspection by the Treaty. The specific instrumentation to be used has to be included in the draft list of the equipment for OSI.
A good characterization of the monitored site needs the capability to observe a small variation on the activity concentrations and the capacity to lower the background contribution.
In order to use the instrument to its full capacity and potential, a transportable shielding has been designed and built-in collaboration with the University of Ferrara, taking into account a good balance between transportability and performance of the system.
The results of a monitoring campaign with and without shielding will be shown and the need to include shielding in the draft list of auxiliary equipment will be discussed.

Speaker: Ms Antonietta Rizzo (Italian National Agency for New Technologies, Energy and Sustainable Economic Development (ENEA), Italy)
• 11:45
OSI Hybrid Power Integration for Base of Operations 15m

One challenge of On-Site Inspection (T2.2) is preparing for deployment to unknown locations with unknown resources. A critical element of a functional Base of Operations is stable and reliable electricity. The current diesel generators and UPS system has been enhanced with a hybrid power system that adds the ability to accept power from other generation sources, such as solar. An increased battery bank allows for more quiet time without the diesel generators reducing fuel usage and CO2 production.
Compact, foldable 100w solar panels have been designed to fit the air transportation containers connecting to inverter hubs that assist the hybrid power unit to supply power to the BOO. Excess energy is stored in battery banks for later use and the design of the system allows for immediate use of solar power anywhere alone the distribution network. The smart controller and control screen allow for efficient management of available power, auto-starting generators as a last resort if required.
Deployable solar units for smaller field equipment such as samplers or pumps complement smaller fuel generators, and small solar mats and converters that clip directly to existing battery terminals provide trickle charge to remotely deployed field equipment (such as SAMs) during sunlight hours.

Speaker: Ms Alana Campbell (CTBTO Preparatory Commission, Vienna, Austria)
• 11:45
Radioactive signs at tunnel portals after underground nuclear tests at Semipalatinsk Test Site 15m

One of the possible manners to conduct a clandestine, unannounced underground nuclear explosion may be a test in a tunnel under a mountain. At the Semipalatinsk test site (STS) of the Soviet Union, 209 underground nuclear tests were conducted in the tunnels. Radioactive noble gas (RNG) release of various intensities occurred at ~40% of the tests. In 1996, the Khlopin Radium Institute conducted a survey at the former STS of about 40 tunnels portals before their final closure. The radiation background was measured, gamma spectra were recorded, rock and soil were sampled for radiochemical analyses. The report will present data on contamination of the surveyed tunnel portal areas by radionuclides Cs-137, Sr-90 and others, and compare them with data on the radiation situation during nuclear tests (RNG release). Remaining radioactive traces are the most important sign during on-site inspection.

Speaker: Mr Yurii Dubasov (Khlopin Radium Institute, St. Petersburg, Russian Federation)
• 09:00 12:00
T2.3 e-poster session: T2.3 - Seismoacoustic Sources in Theory and Practice Online

#### Online

T2.3

Convener: Ms Paulina Bittner (CTBTO Preparatory Commission, Vienna, Austria)
• 09:00 12:00
T2.3 e-poster session: e-poster session - T2.3 - Seismoacoustic Sources in Theory and Practice Online

#### Online

T2.3

Convener: Ms Paulina Bittner (CTBTO Preparatory Commission, Vienna, Austria)
• 09:00
Seismo-acoustic analysis of Mw 4.2 mining induced earthquake nearby Kiruna, Sweden 15m

An earthquake happened in 18 May 2020 early morning in the Kiruna underground iron ore mine (Northern Sweden) having a magnitude Mw 4.2. Following the earthquake, the mine was immediately evacuated because of the risk of aftershocks. This event is the largest mining-induced earthquake that has ever taken place in Scandinavia and it produced signals recorded by three infrasound arrays at distances of 7 km (KRIS, Sweden), 155 km (IS37, Norway) and 286 km (ARCI, Norway). We explore seismo-acoustic features of this event recorded in near and far-field focusing on how the signal propagated in the atmosphere and in the solid earth. Our study provides a detailed comparison between observed and predicted wave front characteristics at the arrays. We also conduct a comparison of amplitude corrected for propagation effect versus magnitude and ground shaking amplitude. These results show that infrasound recorded up to ~300 km from a shallow moderate-magnitude earthquake can provide ground shaking information as well as local amplification caused by topographic and geological features.

Speaker: Mr Antoine L. Turquet (Norwegian Seismic Array (NORSAR), Kjeller, Norway)
• 09:15
An Integrated Study of Seismic and Infrasound for Detecting Non-Tectonic Earthquakes in Indonesia 15m

Indonesia is in an earthquake prone area, not only tectonic earthquakes but also non-tectonic earthquakes. Non-tectonic earthquakes are unique, because they rarely happen. However, in the last decade there have been many non-tectonic earthquakes recorded by seismic sensors due to volcanic activity. Therefore, we need to validate the earthquakes, whether they are caused by tectonic or non-tectonic activity. To distinguish between these earthquakes, we need to integrate parameters between seismic and non-seismic (infrasound) measurement. Tectonic and non-tectonic earthquakes have different frequencies. Non-tectonic earthquakes are dominated by a low frequency and well detected by infrasound measurement, because Infrasound is an acoustic wave with very low frequency less than 20 Hz (~0.01 – 20 Hz).

Speaker: Ms Aldilla Damayanti Purnama Ratri (Indonesian Agency for Meteorology, Climatology and Geophysics (BMKG), Jakarta, Indonesia)
• 09:30
Identifying and tracking regional storms with infrasound data 15m

The infrasound array at Piszkés-tető, Hungary (PSZI) has been operational since May, 2017. Since then PSZI has collected hundreds of thousands detections. These include detections both from known and unknown sources. The categorization of the detections would be important for future automation. The objective of this study is to identify and collect those detections that belong to local and regional storms and lightnings. We present a methodology to identify storms by correlating lightning data from the Blitzortung database we consider as ground truth with the PMCC infrasound detections at PSZI. We also analyze the seasonal variations in the directions and distances of the detected storms.

Speaker: Mr Marcell Pasztor (Eotvos Lorand University, Hungary)
• 09:45
Infrasonic Signatures of 1001 Rocket Launches for Space Missions 15m

In the present study we analyze infrasound signatures of 1001 rocket launches for space missions recorded at stations of the International Monitoring System between 2009 and mid-2020. We include all surface- or ocean-based launches within this period with known launch time, location, rocket type, and mission name; whereas launches of sounding rockets and ballistic missiles for scientific and military purposes, respectively, are excluded from our study. We characterize the infrasonic signatures of over 70 different types of rockets launched at 27 different globally distributed spaceports to estimate the general detectability of rocket infrasound, to evaluate the individual station performance, to quantify propagation and attenuation effects and, finally, to derive a relation between rocket thrust and acoustic energy. Results from the infrasound analysis of the launches will be provided as a DOI referenced dataset for supporting future research on infrasound topics as well as on atmospheric dynamics.

Speaker: Mr Peter Gaebler (Federal Institute for Geosciences and Natural Resources (BGR), Hannover, Germany)
• 10:00
Infrasound Records And Data Analysis For The South Indian Ocean Fireball On March 4, 2020 15m

On March 4, 2020 the Infrasound Stations I03AU, I05AU and I47ZA detected the South Indian Ocean event at 20:26:40 UTC. This detection belonged to a fireball that had a TNT yield equivalent of 1 kiloton (Kt). The infrasonic signals were observed by the three infrasound arrays that are part of the International Monitoring System (IMS) located in Australia and South Africa. The PMCC method was used to estimate the wave parameters at the three infrasound arrays, and the source location (52.11S, 91.15E) was determined by the back azimuth intersection, which is only 100 kilometers away from NASA's location (53.3S, 90.8E).

Speaker: Mr Murad Alhomaimat (Jordan Seismological Observatory (JSO), Jordan)
• 10:15
High frequency events detected by I33MG 15m

High Frequency infrasound are produced generally by explosion, aircraft, storm or lightning…(Campus and Christie, 2010). High frequency infrasound signals are detected by I33MG at the azimuth around 39°. To perform the study, IMS infrasound data from I33MG and I19DJ are processed by mean of PMCC method. After investigation these events are correlated with oceanic storms in the Indian Ocean. In this area, lightning flashes, halo and sprite happen frequently (Christian et al., 2003, Chen et al., 2008) as well as surf events. These events are located at far as 3000 km from I33MG. Frequency of I33MG detections are less than 4 Hz and less than 2 Hz for I19DJ detections. Sources of these events would be strong for having high frequency signal detected for a long distance.

Speaker: Mr Tahina Rakotoarisoa (Institute and Observatory of Geophysics of Antananarivo (IOGA), Madagascar)
• 10:30
Near ground explosion - monitoring with a mobile infrasound array and seismic sensors 15m

The project ABC-MAUS is a collaboration between the Austrian Ministry of Defense, Joanneum Research, the Austrian national weather and geophysical service Zentralanstalt für Meteorologie und Geodynamik (ZAMG), including the Austrian National Data Center (NDC), as well as the private company GIHMM. The aim is to develop a strategy of protection for chemical, biological, radiological and nuclear threads (CBRN) for the Austrian armed forces.

In the frame of the project, a mobile infrasound array was deployed together with seismic sensors to monitor the military training ground Allentsteig in Lower Austria. During one week a series of controlled explosions, originating from different sources, was recorded.

The Austrian NDC developed a tabletop exercise based on a hypothetical explosion. The collected waveform data was analyzed and used to locate the explosion. Once the explosion had been verified by infrasound data, forward modeling assuming a hazardous release was undertaken to understand which areas might have been affected by a resulting toxic plume (reference to contribution by Hieden et al.).

Speaker: Ms Ulrike Mitterbauer (Central Institution for Meteorology and Geodynamics (ZAMG), Vienna, Austria)
• 10:45
Seismoacoustic measurements of surface explosions in Sweden 15m

Seismoacoustic measurements of surface explosions in Sweden are presented. In northern Sweden, near Kiruna, three explosions at one tone each were carried out in August 2020. Further, during 2019, a single considerably larger explosion took place in mid Sweden. For all explosions, seismic and infrasound measurements were made with both temporary and permanent stations in IMS as well as national networks.
Scalings were successfully made for sound pressure level as a function of yield and distance together with local magnitude as a function of yield. The combined measurements allow for a characterization of the explosions both in terms of yield as well as type of detonation (underground, surface or airburst).
Finally, we also present a calibration of a local magnitude scale for northern Sweden that was needed in order to correctly characterize the explosions near Kiruna.

Speaker: Mr Carl Fredrik Hellesen (Swedish Defence Research Agency (FOI),Stockholm, Sweden)
• 11:00
Stromboli volcano eruption 2019-07-03 and atmospheric influence on the detection capability on the infrasound stations. 15m

The International Monitoring System (IMS) is part of the verification regime of the CTBT; in addition, civil and scientific applications are a possible additional benefit that State Signatories could gain from participation in the Treaty verification regime. One of the four technologies used in the IMS is the infrasound network composed of 60 array stations when the network is complete and which is effective for tracking and quantifying volcano eruptions phenomena. In this paper we will focus on one of the most violent eruptions of Stromboli volcano which is one of the most active volcanoes in Italy and on the earth, occurred on 03 July 2019 using data from four IMS Infrasound stations situated in different distance from the Stromboli volcano to observe the detection capability of the Infrasound network in the IMS and the influemce of zonal wind on the infrasound stations detectability as the infrasound propagate in different layer of the atmosphere and depends also on the wind field. The analysis of infrasonic pressure waves generated by Stromboli volcano is essential to the understanding of volcanic explosion. DTK_GPMCC and DIVA software are used to perform this study (Cansi, 1995; Le Pichon, Matoza, Brachet and Cansi, 2010).

Speaker: Mr Abdelouaheb Agrebi (CTBTO Preparatory Commission, Vienna, Austria)
• 11:15
Negative isotropic seismic moment tensors, migrating and cyclic seismicity during the 2018 summit collapse at Kilauea caldera 15m

The 2018 rift zone eruption of Kilauea volcano was accompanied by a remarkable and episodic collapse of its summit. Between May-August the eruption and collapse sequence included over 70,000 earthquakes (M≥0) and 54 major earthquakes (M≥5). We analyzed the seismicity in the Kilauea summit region and estimated seismic full moment tensors with their uncertainties for the 54 M≥5 events. These events occurred at almost daily intervals and were accompanied by intense seismicity which was concentrated between 0-3 km depths beneath the Halema‘uma‘u pit crater. The hypocenters reveal partial elliptical patterns (map view) that migrated downward by ∼200 m. The moment tensors reveal remarkably consistent mechanisms, with negative isotropic source types and localized uncertainties, and vertical P-axis orientations. From the moment tensors we derived Poisson’s ratios which are variable (ν=0.1−0.3) for the first half of the collapse events and converged to ν∼0.28 from June 26 onward.

Speaker: Mr Celso Alvizuri (University of Lausanne, Switzerland)
• 11:30
Seismoacoustic observations using a seismic array on an ice floe 15m

We present the results of seismoacoustic wavefield geophysical measurements carried out at Lake Baikal in the winter of 2020. A system of six special autonomous geo-hydroacoustic buoys, capable of continuously functioning at least for a week, was used as measuring equipment. Each individual buoy consists of a recording system, a seismometer-velocimeter, a hydrophone and wireless data transmission facilities. The measuring system was placed on an ice surface of the lake, forming a seismic antenna system. Lake depth at the locations of some buoys reached 400 m, the ice thickness was 1 m. As a result of experimental data processing, the arrival times of several local earthquakes were identified on ice seismograms. This allows one to study the process of seismic energy transformation into hydroacoustic and back. In addition, a hydroacoustic signal generated by the operation of a distant 100-ton seismic vibrator was recorded in deep water under ice conditions. It can be concluded that geohydroacoustic buoys have demonstrated the convenience and high reliability of use in severe winter conditions. Thus, the possibility of placing seismic arrays on drifting ice floes in the Arctic for solving problems of seismoacoustic monitoring can be considered confirmed.

Speaker: Mr Dmitriy Presnov (Schmidt Institute of Physics of the Earth, Moscow, Russian Academy of Sciences, Russian Federation)
• 11:45
Air and ground vibrations from explosions on the Earth’s surface 15m

Most equations used to predict the ground motion produced by explosions were developed using confined blasts that were detonated with the intention of breaking rock for mining or tunnelling. Ground motion is usually recorded by geophones or seismometers. The air blast produced by open-pit blasts and explosions on the surface can pose a significant risk, thus microphones and pressure gauges are often also used to monitor the effects of the explosion. The aim is to determine whether or not the predictive equations developed for confined explosions can be used to predict the effects from explosions placed on the surface, with appropriate adjustments to the various coefficients.

Three predictive equations developed for buried explosions were tested and it was shown that the United States Bureau of Mines peak particle velocity (PPV) predictive equation is the most reliable. In addition, a predictive equation using the secondary atmospheric shock wave phenomenon also produced good results and is easier to measure. These equations may be utilised both for demolition sites, where old and potentially unstable explosives and obsolete equipment are destroyed on the surface of the ground, and for assisting in forensic seismology to determine the details of an unexpected and unknown explosion.

Speaker: Ms Michelle Grobbelaar (Council for Geoscience, Pretoria, South Africa)
• 11:45
Armenian Seismic Network and Earthquake Catalogue 15m

Seismic networks are a source of valuable data for seismological research. For a few years in cooperation with the French CEA/DASE broadband seismic network in Armenia has been upgraded. Among various tasks in seismological research, the modern network allows improving the quality of the catalog.
The seismicity of the Armenian Upland relates to the Arabian-Eurasian plate collision, which is characterized by the diffusive distribution of shallow earthquakes of various magnitudes. The strong shallow earthquakes are expressed by well-pronounced active surface faulting. Comparison of seismicity of Armenia and the Caucasus with tectonic setting shows that all the strong earthquakes are associated with the active blocks, their edges, and junctions. The analysis of the focal mechanisms of earthquakes with various magnitudes shows the presence of all fault types in Armenia: strike-slip, normal, reverse, thrust, oblique, normal faulting with various components, and with prevailing strike-slip faulting. The combinations of exposure depend on the relatively neighboring block movements. The quality of the Armenian National Catalogue is discussed and the representativeness is described. A unified and homogeneous earthquake catalog is a base for analysis—determination of catalog completeness, recurrence and activity rates, etc., which are the key input parameters for probabilistic seismic hazard assessment.

Speaker: Mr Sos Margaryan (Armenian National Survey for Seismic Protection (NSSP), Armenia)
• 11:45
Bulletin of Iraqi NDC events analysis 15m

Through the International Monitoring System (IMS) of the Comprehensive Nuclear Test Ban Treaty (CTBT) and through their continuous work despite COVID-19, we still benefit from IMS data and the International Data Center (IDC) products. We analyzed many events that occurred and detected via infrasound stations. As the meteor in Turkey on 27 May 2020 which was analyzed with software DTK-(G)PMCC and located with the Geotool and compared results with the catalog reference of analyzed events of NASA. As well as the explosion that occurred in Russia near Achinsk on 5 August 2019, which generated intense infrasound signals including both seismic and acoustic arrivals from infrasound and seismic stations of IMS, and also took the opportunity to analyze and locate event via both the DTK-(G)PMCC and the Geotool.
Through SeisComp3 software already installed in our Iraqi NDC an acquisition system to process the real-time data. We will display an earthquake that occurred On 3 June 2020 at the Iraq-Iran border, which was monitored by the Iraqi seismic stations and detected by SeisComp3 and our local stations not belonging to IMS stations and Geotool for analysis and comparing results.

Speaker: Ms Yasameen Hameed Shamkhi (Iraqi National Monitoring Authority, Iraq)
• 11:45
Characteristics Review for Underwater Explosions based on Depth and Source Types 15m

Most of underwater explosions show characteristics of bubble pulse and reverberation effects. Therefore it is most important to find these two phenomena in order to identify an underwater explosion for any sinking and/or missing a ship or a submarine. The best known studies to find bubble pulse and propagation effects are spectral analysis and cepstral analysis. The review technologies for underwater explosion includes Kursk submarine disaster, ARA San Juan Missing, some Russian underwater nuclear explosion as well as the ROKS Cheonan Sinking which is the main topic in this study. Seismologically it is also the most important to find a positive polarity of the first P-wave arrival from the vertical component record whether or not it is an underwater explosion. Nonetheless it is not always clear to find the upward (compression) of the first P-wave onsets in case of an underwater explosion inside a submarine. This paper is stressed on a shallow underwater explosion near the surface like the ROKS Cheonan Sinking showing a bubble jet characteristic resulting in splitting the ship into two pieces . The phenomena of a bubble jet and a toroidal bubble are highlighted in high resolution spectral analysis for a shallow underwater explosion.

Speaker: Mr So Gu Kim (Korea Seismological Institute, Republic of Korea)
• 11:45
Discrimination of quarry blasts using a complex of seismic and infrasound data in Kazakhstan 15m

The monitoring system of NNC RoK comprises five seismic arrays, eight 3-component stations, and three infrasound arrays. Every year, the network in Central Asia registers and processes some 20,000 seismic events. Among the total bulk of such processed events, about 5,000 events are blasts of different characters. Mainly, they are industrial quarry blasts. The technique has been developed and technology has been generated for recognition of the character of the event based on the set of seismic and infrasound data, which can also increase the accuracy of blast localization significantly on account of reliable reference to the specific quarry. For twelve quarries, template seismic waveforms have been produced. It has been shown that a record of the Lg phase at every quarry at a specific station has a specific form; notably, record forms of this phase from different blasts registered by the same station at the same component for the same quarry are very similar. This feature is used as a criterion for recognition. This technique has been tested with data from the Aqbastau quarry. The findings of this research proved that this method is feasible and highly efficient.

Speaker: Mr Alexandr Smirnov (Institute of Geophysical Research, Almaty, Kazakhstan)
• 11:45
Events Location Using Spectrum From Seismoacoustic Data Of Telesiesmic Stations 15m

A series of earthquakes occurred within the year 2020. These earthquakes were felt both on land and sea. IMS stations in Africa, Europe, and North America that were at teleseismic distances from the epicentre recorded these events. The earthquakes of 3 June & 1 September for Chile and 18 June for New Zealand were analysed using data from seismic and hydroacoustic stations at teleseismic distances as well as Infrasound data from local and regional distances. The waves were extracted and studied by methods of spectrum and azimuth. Results from the analysis showed that the spectrum studies could be used to clear pick the shocks and aftershocks of the earthquakes from stations that are at teleseismic distances from the epicentre. The azimuth from the analysed data was consistent with the known azimuth for the events.

Speaker: Mr Uchenna Onwuhaka Madu (Nigeria Atomic Energy Commission, Abuja, Nigeria)
• 11:45
Examples from data analysis integrating IMS/IDC data with local seismic data in SEISAN 15m

We demonstrate here the advantages of combining data from local seismographs with IMS data in the analysis of both local and distant events. The implementation of new IMS to SEISAN and IDC to SEISAN links makes the integration much easier than before. These links are the results of a project funded by the EU (CELEX 02018D0298-20200423) to facilitate the use of IMS and IDC data at NDCs using the SEISAN package for routine seismic analysis. In this presentation we show how to import parametric data in Nordic format and waveform data in SEED format for a combined analysis of three events: a) an earthquake in West Greenland on 2020-09-27. The regional seismograph network in Greenland is very sparse, and the addition of extra data is extremely valuable. b) an earthquake in Denmark on 2018-09-16 where distant phases can add extra information about the event, and finally c) the DPRK nuclear test on 2017-09-03 which was recorded on both seismographs in Denmark and Greenland. All three events are relocated using the data integration.

Speaker: Ms Tine Larsen (Geological Survey of Denmark and Greenland (GEUS), Denmark)
• 11:45
Finding repeating mining events using waveform cross correlation at seismic and infrasound IMS stations 15m

Mine blasts are an example of repeating seismic/infrasound events with very close epicenters. In some areas, hundreds of mining blasts per year are measured by the IMS and built by the IDC. Waveform cross-correlation is a natural method to detect repeating signals. The IDC has been testing a prototype WCC-based pipeline to find repeating mining events matching the event definition criteria (EDC) for the Reviewed Event Bulletin (REB). The REB is used as a source of master events with seismic and infrasound waveform templates. Several open-pit mines create intensive acoustic waves detected by the IMS infrasound network and these detections are used to build seismic-infrasound events matching the EDC. The prototype pipeline is processing seismic and infrasound data continuously and we systematically compare the cross-correlation bulletin (XSEL) with the automatic bulletin (SEL3) and the REB. This comparison is used to tune the defining parameters of data processing. Here, we present the overall statistics of the continuous processing in the first half of 2021 and the results of offline testing of several mines in Eurasia and USA and two specific time intervals.

Speaker: Mr Ivan Kitov (CTBTO Preparatory Commission, Vienna, Austria)
• 11:45
Generation of S-waves by scattering and conversion revealed by large-N array data 15m

We investigate the origins of seismic S-waves generated by the Source Physics Experiment (SPE), which was conducted near the north end of Yucca Flat at the Nevada National Security Site (NNSS), United States. Understanding the generation of S-waves from underground chemical explosive sources provides physical understanding of regional event screening methods that rely on P-wave and S-wave amplitude ratios. SPE explosions were recorded on a two-dimensional seismic array, enabling us to study the evolution of the near-source wavefield. First, the earth model used for simulations was adjusted until the decay rate of waveform cross-correlation coefficient as a function of inter-station distance matched observations. These comparisons validate the statistical properties of wave scattering in the numerical simulations. We found that adding depth-dependent stochastic variability to the geology-based velocity model improves simulations up to 10 Hz. After model refinement, we used high-frequency simulations and a beaming method to identify the origin of observed wave phases. In addition to waves generated at the source, conversions of Rg to S waves, basin-induced waves, and wave scattering in sedimentary layers were found to be the main mechanisms of shear-motion generation for the SPE-5 explosion source for frequencies below 10 Hz.

Speaker: Mr Arben Pitarka (Lawrence Livermore National Laboratory (LLNL), Livermore, CA, USA)
• 11:45
Infrasound at Costa Rica 15m

The NDC-CR has promoted the use of the infrasound methodology in Costa Rica and in the LAC region with the installation of permanent (IVTCR) and temporary (I069CR) stations in the country, as well as with the organization of regional workshop in the field (Infrasound workshop 2019 jointly by CTBTO and NDC-CR).

The I069CR and IVTCR identified different infrasound sources. Among the most relevant is the fall of the Agua Zarcas meteorite in Central Costa Rica, on April 23, 2019, 21:07 local time, meteorite from which more than 30 kg were recovered by locals and which has had a great impact on the national and international scientific community.

OVSICORI-UNA permanent stations have recorded specific events; for example, the landslide of ~25e+06 m3 on August 26, 2020, 04:00 am local time on the Irazú volcano; recorded by JTS (AS025), which is located ~125km from the source.

Although infrasound instrument had been operating since 2007 at the JTS site and the OVSICORI-UNA seismic network had installed instruments near volcanic sources, it is until recently that the community had shown interest in this methodology and the CTBTO jointly with the NDC-LAC could play an important role to build capacity in the field.

Speaker: Mr Ronnie Quintero (Observatorio Vulcanologico y Sismologico de Costa Rica (OVSICORI), Costa Rica)
• 11:45
Infrasound Bulletin from local and regional sources by the NDC of Costa Rica between 2018 and 2020 and integration of data from I20EC, I51GB, I08BR, I09BR (IMS) infrasound stations with local volcanic infrasound monitoring networks and portable array I69CR (CTBTO) 15m

Since 2018, the inclusion of infrasound monitoring in active volcanoes in Costa Rica with local networks has been implemented by OVSICORI-UNA. In addition, at the end of 2018, two portable infrasound arrays were installed, such as I69CR and IVTCR in cooperation with CTBTO and UNIFI. The NDC-CR includes the integration of IMS stations such as I20EC, I51GB, I08BR, I09BR, thus making it possible to use the event location option through back-azimuth triangulation for relevant local and regional events in the region of Central America and the Caribbean. Among the relevant events from local and regional infrasound sources analyzed for the Infrasound bulletin are the following. Volcanic events: small volcanic explosions (Rincón de la Vieja Volcano, Turrialba Volcano, Poas Volcano between 2018 and 2020). Events of fireballs or meteorites detected in the I69CR portable station and IMS stations: Fireball over Bering Sea 2018-12-18, Cuba Meteorite 2019-02-01, Haiti Meteorite 2019-04-14, Costa Rica Aguas Zarcas Meteorite 2019-04-24, Meteorite South East New Orleans 2019-05-04, Fireball over Caribbean South Puerto Rico 2019-06-22, Meteorite North Puerto Rico 2020-01-17. Seismic events: Earthquake between Costa Rica and Panama of 2019-06-26. Irazú Volcano landslide event August 26, 2020.

Speaker: Mr Hairo Villalobos (Observatorio Vulcanologico y Sismologico de Costa Rica (OVSICORI), Costa Rica)
• 11:45
Microseismic Activity in Armenian Upland 15m

Seismic networks are a source of valuable data for seismological research. Since 2010 in cooperation with the French CEA/DASE, the broadband seismic network in Armenia has been upgraded. Digital seismological stations were deployed in the territory of Armenia and they are providing data that enabled to conduct of various research activities, including the study of microseismicity and active tectonics in the region.
The seismicity of the Armenian Upland relates to the collision of Arabian and Eurasian plates, which is characterized by a diffusive distribution of shallow earthquakes of various magnitudes.
The strong shallow earthquakes as well as microearthquakes are expressed by well-pronounced active surface faulting. The microearthquake pattern observed over the past few years is consistent with the tectonic pattern of the study area including historical seismicity. In general, the seismicity in the Armenian Upland correlates with the known geologic structures. The microseismic activity also was studied from the point of view of large crustal earthquakes preceding.

Speaker: Mr Sos Margaryan (Armenian National Survey for Seismic Protection (NSSP), Armenia)
• 11:45
QSDA (Quality Seismic Data Assessment): On line Web Base of Power Spectral Density for Seismic Noise Quantification 15m

The development of the seismograph network in Indonesia has been massive in the last two years. As more and more seismographs are installed, it is hoped that continuous data and high-quality data will be obtained. The presence of noise in seismic waveforms greatly disrupts the identification of earthquake events. Various potential sources of seismic noise exist, such as: ocean waves, meteorological effects and human activities. Choosing a location for a sensor that has a low noise level is very important to get a high quality earthquake data recording. Therefore, we developed a power spectral density application to identify and to quantify seismic noise. This web-based Power Spectral Density (PSD) application operates online and flexible time window. The principle of seismic quantification used in this method is the Peterson Noise Model. This application can be used to determine the quality of data from all seismograph stations on a regular weekly or monthly basis.

Keywords: seismic noise, waveform, PSD

Speaker: Mr Supriyanto Rohadi (Indonesian Agency for Meteorology, Climatology and Geophysics (BMKG), Jakarta, Indonesia)
• 11:45
Remote hydroacoustic and infrasonic detection and characterization of eruptive activity leading to, during, and following the December 2018 major flank collapse and tsunami at Anak Krakatau 15m

A climactic eruption phase on December 22, 2018 triggered the collapse of the southwest flank and summit of Anak Krakatau stratovolcano, generating a tsunami which struck Sumatra and Java. We employ a selection of remote moored hydroacoustic (H08S, 3,307 km; H01W, 3,720 km) and infrasonic (IS06, 1,156 km; IS07, 3,475 km; IS52, 3,638 km) stations of the International Monitoring System (IMS) to investigate eruptive activity preceding, during, and after the climactic eruption phase. We observe 6 months of co-eruptive intermittent infrasound at IS06, and powerful infrasound from the climactic eruption on IS06 and IS52. The climactic eruption phase was not detected hydroacoustically, but we observe a ~12-day swarm of hydroacoustic signals beginning 24 days before the flank collapse event that we attribute to sustained submarine eruptive activity at Anak Krakatau. We perform waveform multiplet analysis to assess similarity of infrasound and hydroacoustic events. Impulsive infrasonic events recorded during the main infrasound-generating eruption are similar, indicating repetitive explosions at Anak Krakatau. Hydroacoustic event families at H08S are less similar, indicating a possible range of submarine eruption processes and signal types. This study further underscores the potential of remote acoustic technology for detecting and characterizing eruptions at submarine or partially submerged volcanoes.

Speaker: Kaelynn Rose (University of California, Santa Barbara, CA, USA)
• 11:45
Source Detection and Risk Evaluation of Ru-106 Event of 2017 in Europe 15m

Considerably high levels of Ru-106 were measured by some air monitoring stations in Europe at the end of September and beginning of the October in 2017. Routine measurements revealed Ru-106 levels that vary between 10 to 100 mBq/m3 with maximum values reaching as high as 150 mBq/m3 during this period. Based on this motivation, a mathematical modeling study for the atmospheric transport of Ru-106 was performed to locate possible sources of this radionuclide. Using inverse modelling methods, potential Ru-106 source were analysed via FLEXPART, a Lagrangian particle dispersion model. The model was used in backward mode to locate possible sources of Ru-106 event of 2017. The model was later used in forward mode to simulate atmospheric dispersion and ground level deposition of Ru-106 in Europe considering the possible identified sources. The backward and forward simulations performed in this study used ECMWF datasets. Concentration and deposition results were compared with available data recorded by the European environmental radiological monitoring networks. In addition, possible transport routes and deposition of Ru-106 in Turkey were also estimated to identify potentially contaminated regions in Turkey. Finally, various dose values were estimated using model outputs for health and environmental risk evaluation purposes.

Speaker: Mr Efem Bilgic (Dokuz Eylul University, Izmir, Turkey)
• 11:45
The 7th July 2011 Abadan, Turkmenistan explosions: A seismoacoustic analysis 15m

At 11:40 (UTC) on 7th July 2011, a series of accidental explosions occurred in the town of Abadan, Turkmenistan. The Turkmenistan government listed the cause of the accident as the ignition of pyrotechnic matter intended for fireworks, which then spread to military storage areas, where an estimated 5,000 - 50,000 tons of ammunition was stored (Boggs et al., 2013).

The explosions are clearly observed ~11 km away at the International Monitoring System (IMS) seismometer array GEYT (Turkmenistan). A total of 30 individual events can be identified. Yields are estimated using P-wave (Koper et al., 2002) and Rg amplitude (Bonner and Russell, 2013) and range between 0.5 – 45 tonnes (TNT equivalent).

IMS infrasound arrays in Kazakhstan, Russia, and Germany observed these explosions. A yield for the largest explosion(s) (4 – 90 tonnes) is determined using the dominant period of these infrasonic signals (Whitaker, 2006), and is consistent with the yield determined using seismic observations.

Air-to-ground coupled waves at GEYT exhibit downward first motions, consistent with an initial positive blast overpressure. We measure the period and peak-to-peak amplitude of the air-to-ground coupled waves and find amplitude varies with yield but not period.

Speaker: Mr Stuart Nippress (AWE Blacknest, Reading, United Kingdom)
• 11:45
ThunderSeis: Seismic analysis of thunder signals recorded at the Gaisberg mountain, Austria 15m

Lightning strokes create powerful wavefields of seismoacoustic nature, which we refer to as thunder. Unfortunately, even though bolts of lightning received much attention in such fields as physics of plasma and meteorology, less research was conducted to investigate the thunder itself.

A radio tower on the top of the Gaisberg mountain in Salzburg is permanently instrumented with electrical sensors able to record the current of lightning strokes hitting the tower’s top. In October 2020, observations of 5 thunder signals have been made using several one-component seismic sensors. At the same time, this tower is instrumented with a meteorological station, which allows us to model precisely the propagation of seismo-acoustic thunder signals from the above-mentioned lightnings.

These observations and modeling give insight into how thunder is created during the lightning stroke, which is an important milestone for seismo-acoustic observations of atmospheric events.

Speaker: Mr Artemii Novoselov (University of Vienna, Vienna, Austria)
• 11:45
Understanding mb Variations: The Implications of a Global IMS 15m

When complete, the International Monitoring System (IMS) will include 170 seismometer stations. These stations consist of various seismometer types, and are located in a range of geological and tectonic settings. The data recorded can be used to determine the body-wave magnitude (mb) of a seismic event, which is used in the mb:Ms event screening criterion applied at the International Data Centre (IDC). Event screening being the rejection of the null hypothesis that an event is a single point underground explosion. Initial development of the mb magnitude scale (and the mb:Ms criterion) was mainly based on body-wave data recorded by standard short-period instruments. Today, the IMS consists of a range of short-period and broadband instruments with a variety of responses.

Our work seeks to understand the implications of varying instrumentation and the potential impact on the mb values measured, as well as investigating the effect of variations in attenuation. Initial results suggest that a combination of these variables has the potential to affect the consistency of event mb magnitudes using the current IDC mb measurement method. We consider alternative methods which could prove more robust.

Speaker: Ms Jessica Keeble (AWE Blacknest, Reading, United Kingdom)
• 11:45
Use of small-aperture, near-source seismoacoustic arrays in characterizing low-yield chemical explosive sources 15m

Ground-truth (GT) recordings of low-yield quarry blasts at near-source distances provide a means of assessing the accuracy of seismoacoustic arrays in detecting and characterising explosive events. Infrasonic recordings from surface explosions generally show superior signal-to-noise (SNR) ratios compared to seismic detections, however dynamic atmospheric conditions introduce uncertainty. For detection of low-yield explosions in urban environments, small-aperture arrays of collocated seismic and acoustic sensors should perform well in a greater variety of conditions. We deployed two six-node, small-aperture seismoacoustic arrays in near Labrador City and Ottawa, Canada, over month-long periods. Using an empirical approach, we develop amplitude and period scaling relationships for estimating yield at distances 3-70 km using GT event details (timing, location, explosive yield) provided by mine and quarry operators. The sources are ripple-fire detonations spaced milliseconds apart. The blast durations are ~10-30 seconds, and origin times are generally accurate to within seconds. Blast yields are 3-1000 T of TNT equivalent and associated seismic magnitudes are approximately 1.3-2.9 MW. We show that seismoacoustic data are complementary and, when combined, result in more accurate blast characterisation.

• 09:00 12:00
T2.4 e-poster session: T2.4 - Atmospheric and Subsurface Radionuclide Background and Dispersion Online

#### Online

T2.4

Conveners: Mr Jonathan Bare (CTBTO Preparatory Commission, Vienna, Austria) , Robin Riedmann (CTBTO Preparatory Commission, Vienna, Austria)
• 09:00 12:00
T2.4 e-poster session: e-poster session - T2.4 - Atmospheric and Subsurface Radionuclide Background and Dispersion Online

#### Online

T2.4

Conveners: Mr Jonathan Bare (CTBTO Preparatory Commission, Vienna, Austria) , Mr Robin Riedmann (CTBTO Preparatory Commission, Vienna, Austria)
• 09:00
An investigation on the IMS noble gas stations network coverage: 2015-2019 15m

This paper evaluates the desirability of noble gas stations network coverage in the International Monitoring System of the CTBTO for the detection of 1 kt nuclear explosions. It was assumed all the 39 noble gas stations become active, the annual average of MDC was used for each certified station and the MDC of Non-Operational Stations was considered 0.24 mBq/m3. In this regard, the daily network coverage of IMS noble gas stations was analysed using SRS fields based on the 14 days backward modeling from 2015 to 2019. The daily, monthly, and annual average of network coverage were calculated and investigated in the form of image pattern and the numerical value corresponding to the global latitude/longitude grid. The results indicated that using the mean coverage over space and time makes some misconceptions, hence the network coverage was evaluated based on an event spatial distribution which provides a real understanding to assess the network coverage for the state parties.

Speaker: Mr Hamed Abdollahnejad (Amirkabir University of Technology (AUT), Tehran, Iran)
• 09:15
Isotopic transport variation as a function of environmental conditions 15m

As gaseous and particulate signatures are produced during an underground nuclear explosion, it is important to understand their transport to the surface for subsequent atmospheric transport and detection. By understanding the transport throughout the subsurface, the atmospheric measurements have the potential to allow for a better understanding of the fractionation and total release fraction of radionuclides from a nuclear explosion. We have performed microscale studies of formation of particulate and transport of gaseous species within a variety of geologic media. In this presentation, we discuss the use of exploding wires to simulate the formulation of particulate and the use of inverse gas chromatography to characterize gas transport parameters for a variety of geologic media.

Speaker: Mr Michael Foxe (Pacific Northwest National Laboratory (PNNL), Richland, WA, USA)
• 09:30
NPE19 source term reconstruction based on radionuclide monitoring result 15m

NDC Preparedness Exercises (NPE) are regularly performed to practice the verification procedures for the detections of nuclear explosions in the framework of CTBT monitoring. In the event of NPE2019, a fictitious state RAETIA announced that a reactor had an incident and some radionuclides were released into the atmosphere. Both the IMS data and data from a fictitious neighbour state, EASTRIA, were provided to participants, and EASTRIA requested assistance from the IDC, called Expert Technical Analysis (ETA). The work we have done is radionuclide detections data analysis, ATM in backward mode by flexpart, source reconstruction in bayesian method.

Speaker: Mr Yungang Zhao (CTBT Beijing National Data Centre and Beijing Radionuclide Laboratory, Beijing, China)
• 09:45
Characterization of radioxenon global background between 2015 and 2020 15m

Worldwide monitoring of radioxenon is a necessary component of the International Monitoring System (IMS) of the Comprehensive Nuclear-Test-Ban Treaty (CTBT). The current IMS design foresees 40 radioxenon stations around the world to provide a 90 % detectability of a 1 kt nuclear explosions within 14 days. Radioxenon stations have the capability to measure four radioxenon isotopes; 131mXe, 133Xe, 133mXe, and 135Xe. The discrimination between radioxenon emission from civil sources and xenon released from a nuclear explosion is achieved by analyzing different ratios between the four xenon isotopes. In the present work, we systematically study the development of the four Xe isotopes background between 2015 and 2020, and its geographical distribution according to the measurements from the IMS stations.

Speaker: Mr Mohammed Yehia Taha Ahmed Elbahrawy (National Research Institute of Astronomy and Geophysics (NRIAG), Helwan, Egypt)
• 10:00
Source reconstruction from dry and wet deposition measurements 15m

Measuring airborne radioactivity typically requires large, static installations, limited in number and geographical distribution. By measuring the activity of matter deposited to the ground (by dry settling or wet scavenging), one can complement detections of airborne activity and improve overall data availability.

Many ways exist to detect deposited activity, such as using rain basins which capture precipitation for a known span of time, or directly sampling soil or bodies of water. The latter have certain drawbacks (e.g. ambiguity as to what timeframe of atmospheric activity is actually covered by the sample) leading to large uncertainties, but have the advantage that data can be gathered anywhere and at any time (including days or weeks after a plume of interest has already come and gone), without requiring any preexisting infrastructure.

This presentation compares between atmospheric- and deposition-based detection as practical techniques by treating a series of cases simulating individual 'puff' releases. In every case, we determine how sensitive the existing network of International Monitoring System (IMS) stations would be to the release, and subsequently the surface area which a hypothetical rain collection basin would require at every location to match the sensitivity to the release that is achieved by the IMS stations.

Speaker: Mr Max Schönlank (Belgian Nuclear Research Centre (SCK CEN), Mol, Belgium)
• 10:15
Preliminary analysis results of ongoing temporary radioxenon background measurement campaign in Japan 15m

In 2017, the Government of Japan has decided to make a voluntary contribution to further enhance the capabilities of the CTBTO verification regime. In that framework, two transportable noble gas systems were deployed in Horonobe and Mutsu. They respectively started operating in February 2018 and March 2018. Continued operation of the two systems is now financially supported with funding from European Union Council Decisions.

Together with the IMS station RN38 in Takasaki, this forms a temporary high-density configuration network enabling observation of the same event release at different locations at distances of about 500 km from each other.

As of today, few thousands of samples were already collected and measured in Mutsu and Horonobe, and this number is still increasing daily. Resulting spectra are automatically sent to the IDC and processed in a non-operational database. They are routinely reviewed, and the concentrations of the four xenon isotopes of interest for the CTBTO (131mXe, 133mXe, 133Xe and 135Xe) are calculated. Analysis results are made available (together with raw data) to State Signatories through a Secure Web Portal.

In this work, preliminary analysis results of ongoing temporary background measurement campaigns are presented.

Speakers: Mr Jonathan Bare (CTBTO Preparatory Commission, Vienna, Austria) , Ms Jana Meresova (CTBTO Preparatory Commission, Vienna, Austria)
• 10:30
Global radioxenon emission inventory 2014 from all types of nuclear facilities 15m

The goal of the third ATM challenge is to perform atmospheric transport modelling in order to estimate radioxenon observations at selected IMS stations in the northern hemisphere for an extended period in the year 2014 (June to November). This estimation is needed for calibration and performance assessment of the verification system as described in the Treaty. The best estimates for Xe-133 emissions from known sources is used as input data for this exercise. This presentation summarizes the global radioxenon emissions inventory for the whole year 2014. It comprises all relevant nuclear facilities. For the two strong sources IRE (Belgium) and CRL (Canada) stack release data with a high time resolution are available. For nuclear power plants (NPP) in Europe and the USA the reported release for the whole year are applied in combination with information about their operational schedule. For all other NPPs and for the strongest research reactors sources the best estimates are used. The estimated release of the strongest nuclear research reactors sources is included as well as the annual emissions from the Mallinckrodt facility (The Netherlands), the NIIAR facility (Russia) and the Karpov Institute (Russia).

Speaker: Martin B. Kalinowski (CTBTO Preparatory Commission)
• 10:45
Non-parametric study of the radioxenon data distribution, measured at the noble gas stations of the International Monitoring System of the CTBTO 15m

The aim of this work is to apply a non-parametric statistical methodology to the radioxenon activity concentrations measured at noble gas stations of the International Monitoring System of the CTBTO, in order to investigate the radioxenon atmospheric background and the radioxenon anomalous values. The proposed non-parametric statistical methodology does not require any assumption on the underlying probability distribution of the raw data. The suggested method, based on Recursive Segmentation and Permutation (RS/P), allows to detect single or multiple mean and/or scale shifts.

Speaker: Mr Giuseppe Ottaviano (Italian National Agency for New Technologies, Energy and Sustainable Economic Development (ENEA), Italy)
• 11:00

The most important indicators for an underground nuclear explosion during a CTBT on-site inspection are the radioactive xenon isotopes 131mXe, 133Xe and 133mXe and the radioactive argon isotope 37Ar. Knowledge of how these isotopes vary and potentially correlate in different types of soil is essential to be able to discriminate between the natural background and a signal from a nuclear explosion.
A series of measurements has been performed at different depths within a limited area in the region of Kvarntorp (Sweden), a location with known elevated uranium content in the ground. To investigate variations of the naturally occurring noble gas concentration in sub soil gas over time and at different depths sub soil sample collection was carried out over a period of two weeks. The analytical results from the collected samples will be discussed in relation to radon levels, soil uranium content and environmental parameters such as the meteorological conditions.

Speaker: Mr Mattias Aldener (Swedish Defence Research Agency (FOI),Stockholm, Sweden)
• 11:15
How to Use the FLEXPART Model in Atmospheric Transport Modelling Challenges 15m

The “Flexible Lagrangian particle dispersion model” FLEXPART is used in the IDC as well as by many of the participants in the Atmospheric Transport Modelling Challenges. As a truly flexible model, it may be used in forward and backward mode and it has many other parameters that can be set by users. All of these options influence the CPU and memory requirements as well as the accuracy of the output. For example, if we consider only a small number of stations and daily or half-daily samples, but are interested in a large number of of possible emitters and/or emission time slots, backward simulations will usually be more efficient. There is also the option of using gridded output or a point receptor with a sampling kernel. Number of particles and model time steps also influence both the resources required and the results. For the ATM Challenge 3, certain modifications have been implemented in FLEXPART version 10 to make full use of possible combinations of options. Pertinent findings and recommendations will be reported.

Speaker: Ms Petra Seibert (University of Vienna, Austria)
• 11:30
Atmospheric and Subsurface Radionuclide Background and Dispersion 15m

A general code has been developed to describe two phase flow, tracer transport and thermal effects through a fractured porous medium on the Darcy scale under the action of constant or time dependent pressure fluctuations. The fractures are modeled as surfaces with specific properties. The fluid properties can depend on pressure and temperature.
The equations for flow, tracer concentration and temperature are discretized by the finite volume method on triangular and tetrahedral meshes.
The three modules which compose the code, namely flow/energy/tracer transport are parallelized by the OpenMP technique and shown to function satisfactorily separately and in interaction.
Applications of this code are made to a typical situation of interest with an underground cavity and a potential chimney. The dimensions of the geological medium above are 100x100x400m; it contains 147 fractures of radius 20 m and of equivalent aperture 1 mm. The fracture network is percolating from the cavity up to the surface. The initial pressure is 200 bars and the temperature 1000 K. All these characteristics can be modified at will.
Pressure, temperature, and concentration evolutions as well as surface fluxes will be presented and discussed.

Speaker: Mr Aliaksei Pazdniakou (Sorbonne Université, Paris, France)
• 11:45
A study of the radioxenon background and potential sources at the IMS station SEX63, Sweden 15m

Understanding the radioxenon background at the radionuclide stations in the IMS network is important to improve the verification capability of the network. The background at the IMS station SEX63 in Stockholm Sweden has been studied in the time period between 2012 to 2019 using data from the IMS SAUNA II system. From 2017 data have also been evaluated from the co-located SAUNA III system. Xenon detections have been studied to understand potential sources and their contributions to the detections at the station. Detections have been characterized with respect to concentrations, isotopes detected and wind direction. ATM has been used to try to identify specific sources in a few case studies.

Speaker: Mr Mattias Aldener (Swedish Defence Research Agency (FOI), Stockholm, Sweden)
• 11:45
Analysis of Atmospheric Radioxenon Detections in the UK 15m

An IMS-like noble gas system is in operation at AWE (Aldermaston, UK) and can collect and measure the radioxenon content in environmental air samples. When operated in this mode, data produced is analysed at the UK National Data Centre (NDC) as part of the in-house radionuclide (RN) analysis pipeline. This work discusses a number of significant detection events analysed using the operational system deployed at the UK NDC, which includes atmospheric transport simulations and a real-time stack-monitoring data feed from a nearby medical isotope production facility in Belgium. A comparison of the expected radionuclide contributions with measured detections is presented, including a comparison of the isotopic ratios for the radioxenon isotopes of interest (Xe-133, Xe-131m, Xe-133m, Xe-135).

Speaker: Mr Matthew Goodwin (AWE Aldermaston, Reading, United Kingdom)
• 11:45
Applications in CFD in nuclear emergency response decisions 15m

Speaker: Mr Carlos Eduardo Santos Bonfim (CBRN Defence Institute (Brazilian Army), Rio de Janeiro, Brazil)
• 11:45
Atmospheric Transport Model Applied to the Design of Nuclear Facilities 15m

Xenon emissions from medical isotope production facilities (MIPFs) and other nuclear installations affect the verification capability of the International Monitoring System (IMS) of the Comprehensive Nuclear Test Ban Treaty Organization (CTBTO). In an effort to minimize the impact of this radioxenon and in order to mitigate, in general, the radionuclide emission, Atmospheric Transport Models are applied at INVAP on different stages of the design and development of type of facilities.
The design includes safety protection radiological analyses, either inside or outside the installations, and monitoring of gaseous effluent release into the atmosphere considering both normal operation as well as accidental cases.
In this work, examples of different capabilities and results for different cases are shown. The safety analyses are based on conservative Gaussian Plume models, which include the evaluation of systems performance, operational cases, atmospheric dispersion and transport of radionuclides, meteorological conditions, emission parameters and site characteristics.

Speaker: Ms Mariana Alessi (INVAP S.E., Bariloche, Argentina)
• 11:45
Baseline assessment of radionuclides and heavy metals in groundwater, surface water and soil along with their potential human health risk in the vicinity of Rooppur nuclear power plant, Bangladesh 15m

The concentrations and distributions of natural and anthropogenic radionuclides and heavy metals in surface water, groundwater, and soil samples of the site of Rooppur Nuclear Power Plant which is being constructed were investigated with the aim of evaluating the environmental radioactivity and radiation hazard and associated health risk assessment. Water and soil samples were collected and analyzed the levels of radionuclides and heavy metals using ICP-MS, Gamma-ray Spectrometry together with AAS. The heavy metal evaluation index (HEI), Nemerrow pollution index (NI) were applied to identify how different heavy metals pollute the groundwater in the studied sampling sites. According to USEPA 1999, HQ and HI value for adults through oral exposure pathway in groundwater shows the medium level of chronic risk and in surface water shows a low level of chronic risk. The estimated effective dose, as well as annual effective dose due to intake of different radionuclides, are significantly lower than both the World Health Organization (WHO) and the International Commission on Radiological Protection limits. The concentrations of 226Ra, 232Th, and 40K in soil samples, radium equivalent activity for soil, absorbed dose rates, external hazard (Hex) values were determined. No artificial radioactivity (137Cs) was found in these samples.

• 11:45
Characterizing the background variability of radionuclides at International Monitoring System stations 15m

A variety of factors influence the atmospheric background of ubiquitous radionuclide signatures, like xenon-133, measured at International Monitoring System (IMS) stations. Variability in the radionuclide background obscures the categorization and discrimination of signals from nuclear weapons testing and civilian and industrial activities tied to medical radioisotope production and nuclear power reactors. The radionuclide background fluctuates due to synoptic weather events, temporal changes in background sources, and site-specific details related to the placement of IMS stations. To better characterize the radionuclide background, we have statistically analyzed a set of factors that may be associated with background variability. These factors include historical IMS measurements, weather reanalysis products, high-resolution spatial topographic and land-use data, and a large collection of atmospheric transport modeling simulations. We use this dataset to assess the relationships between potential background sources, site-specific characteristics, and signals at IMS stations, including an assessment of stations susceptible to large variations in background. This assessment may improve our understanding of the radionuclide background and may aid event characterization and analysis of data at the International Data Centre.

Speaker: Mr Donald Lucas (Lawrence Livermore National Laboratory (LLNL), Livermore, CA, USA)
• 11:45
Comparative study of the transient and steady state thermal hydraulics analysis of the Low Enriched Uranium (LEU) core of Ghana Research Reactor-1 (GHARR-1) 15m

Countries seeking a quick bomb or would-be nuclear terrorists have eyes on poorly secured sites that contain significant quantities of high enriched uranium, (HEU). HEU is the material of choice for states or terrorists that seek to proliferate stealthily without testing their weapons. It is therefore critical to make current stocks of HEU as inaccessible as possible. One of the most effective long term approach is to eliminate it from as many locations as possible and convert the HEU cores to low-enriched uranium (LEU) core. The high enriched uranium core of the Ghana Research Reactor-1 has been converted to a low enriched uranium core. The transient and steady state thermal hydraulic analysis of the LEU core of Ghana Research Reactor -1 is presented in this work. The Monte Carlo N Particle code (MCNP-5) was used in obtaining neutronic parameters for the transient and steady state simulations. PARET/ANL was used in simulating transient responses of the GHARR-1 LEU core and PLTEMP/ANL was also used for the steady state simulations. Results obtained in both transient and steady state compared well with the experimental data.

Speaker: Mr Prince Amoah (Nuclear Regulatory Authority, Accra, Ghana)
• 11:45
Comparison of modelled atmospheric radionuclides from the Fukushima Dai-ichi nuclear accident with CTBTO station measurements. 15m

The global atmospheric dispersion and deposition of radionuclides released from the Fukushima Dai-ichi nuclear power plant accident was modelled using the EMAC atmospheric chemistry – general circulation model at different esolutions (equivalent to ∼50 km and ∼110 km Gaussian grid). The model accounts for emissions and transport of the radioactive isotopes 131I and 137Cs, and removal processes through precipitation, particle sedimentation and dry deposition. In addition, we simulated the release of 133Xe, a noble gas that can be regarded as a passive transport tracer of contaminated air. Modeled surface concentrations were compared to station observations by the Comprehensive Nuclear-Test-Ban Treaty Organisation (CTBTO) global monitoring network for a number of stations through the CTBTO Virtual Data Exploitation Centre.

Speaker: Mr Theodoros Christoudias (The Cyprus Institute, Nicosia, Cyprus)
• 11:45
Development of New Methods for Measuring Concentration Activities I-131 Using Direct and Indirect Methods in Radioisotope Production Stacks, in the Environment and in Settlements (Indoor and Outdoor) 15m

Radioisotope Production Facility in Serpong, has produced and processed I-131 which can be dispersed to residential areas and the environment around the Serpong Nuclear Zone (SNZ). Measurement of the air release dispersion I-131 using an old analogue tool is not functioning, and only a charcoal filter is functioning in the stack of the isotope production facility. Measurement of the I-131 dispersion to the environment and houses around SNZ has not been carried out. Therefore, it is necessary to develop a new method of measuring the release of I-131 concentration in the stack combined with equipment from the CTBTO and I-131 measurement in the environment and settlements (indoor and outdoor) around the SNZ. Direct measurements using a portable in-situ NaI(Tl) detector were carried out in the house, environment, and using the LaBr3 detector in the stack. Indirect measurements using charcoal filters and vacuum pumps were carried out in the stack and outdoors. The newly developed I-131 discharge measurement method can be used to replace the I-131 analog method, because the new measuring system can be operated rapidly and continuously. The concentration of I-131 during rain and high humidity tends to increase, while the presence of sunlight reduces the concentration of I-131.

Speaker: Mr Gatot Suhariyono (Indonesia National Nuclear Energy Agency (BATAN), Jakarta, Indonesia)
• 11:45
Devices to reduce the emission of radioactive noble gases into the environment 15m

The Fission Radioisotope Production Plant of Argentina, located at the Ezeiza Atomic Center, produces 99Mo since 1985 irradiating targets with High Enrichment Uranium. In 2002 the targets have been changed by Low Enrichment Uranium.
Facilities that produce radioisotopes by fission increase the background of noble gases in the environment, especially radioactive xenon.
This background could interfere with the CTBTO assessments of nuclear explosions.
The work will show the production method for 99Mo and 131I that is carried out in Argentina, the emission levels and production during the last years. The current measurement system will also be described.
Finally, different mechanisms for the reduction of noble gas emissions and a comparative study of the advantages and disadvantages of each of them will be presented.

Speaker: Mr Eduardo Carlos Carranza (Comisión Nacional de Energía Atómica de Argentina, Argentina)
• 11:45
Effect of 2020 Chernobyl Exclusion Zone Wildfires on the IMS Radionuclide Stations Network 15m

Wildfires broke out on the 3rd of April 2020 in the Chernobyl exclusion zone, and the fires lasted for several weeks. As a consequence, measurable amounts of Cs-137 were re-suspended into the atmosphere and observed through the IMS network. Over the period of April - May 2020, the International Data Centre reported a significant increase in the number of Cs-137 detections compared to the same period in the previous years.
In this poster, all the stations from the IMS network that reported Cs-137 over the period into consideration are first given. Based on Atmospheric Transport Modelling (ATM) simulations, stations impacted by the plumes from Chernobyl were determined, and the effects of the wildfires were assessed through (1) measured activity concentrations of Cs-137 and (2) Cs-137-to-K-40 ratios. Finally, the impact of such natural events on the categorization of IDC products is also illustrated through the evolution of relevant discrimination thresholds.

Speaker: Mr Seokryung Yoon (CTBTO Preparatory Commission, Vienna, Austria)
• 11:45
Evaluating the added value of multi-input atmospheric transport ensemble modeling for applications of the Comprehensive Nuclear Test-Ban Treaty Organization (CTBTO) 15m

The potential benefit of ensemble dispersion modeling for CTBTO applications was investigated using input data from the ECMWF-Ensemble Prediction System (EPS). Five different test cases - among which are the ETEX-I experiment and the Fukushima accident - were run. For those test cases run in backward mode and based on a puff release it became evident that Probable Source Regions (PSRs) can be reduced in size compared to results based solely on the deterministic run by applying minimum and probability of exceedance ensemble metrics. It was further demonstrated that a given puff release can be reproduced within the meteorological uncertainty range. For the test cases run in forward mode it was found that the control run, 10- and 51-member medians exhibit similar performance in time series evaluation. The main added value of the forward ensemble lies in producing meteorologically induced concentration uncertainties and thus explaining observed measurements at specific sites. It can be concluded that meteorological uncertainty to a large degree is covered by the 10-member subset because forecast uncertainty is largely suppressed due to concatenating analyses and short term forecasts, as required in the operational CTBTO procedure, and because members from different analyses times are on average unrelated.

Speaker: Mr Christian Maurer (Central Institution for Meteorology and Geodynamics (ZAMG), Vienna, Austria)