Detection of radionuclides released from a nuclear explosion is an essential task performed by the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) as mandated under the Comprehensive Nuclear-Test-Ban Treaty. Identifying possible source regions for relevant radionuclide observations and identifying potential stations for measuring releases from known source locations is done by...
Starting with 2009, three infrasound stations have been deployed on the Romanian territory by the National Institute for Earth Physics: (1) IPLOR (in central Romania), (2) BURARI (in northern Romania) – under cooperation with AFTAC (USA), and (3) I67RO temporary PTS portable array (in western Romania) as a two-year experiment (2016-2018), within a collaboration project with the Provisional...
Four technologies are used for compliance verification of the comprehensive Nuclear-Test Ban Treaty (CTBT), hydroacoustic, infrasound, seismic and radionuclide monitoring. Forty radionuclide stations will have the radioxenon monitoring capability. For the last few years, a lot of research have been done in order to discriminate radioxenon derived from an explosion and anthropogenic sources....
International Monitoring System H phase stations have great potential for submarine earthquake monitoring in the southern hemisphere. The hydrophones could record low frequency sounds from extensive areas. However, some seismic signals from different areas would have similar characteristics in a short time interval. It is difficult to locate the epicenter using only the azimuth and arrival...
We apply a current state-of-the-art machine learning based denoising algorithm on the seismological and hydroacoustic waveform records of the selected Democratic People's Republic of Korea nuclear tests. We use the DeepDenoiser algorithm to reduce the noise present in the waveform records of the larger Democratic People's Republic of Korea nuclear tests. The denoising of waveform records using...
The US National Data Centre (NDC) observed five relatively large seismic events in the Chhattisgarh Province of India from September 2018 through October 2022. These events are of interest as they exhibit some explosive characteristics, and their respective yields are approximately equivalent to a 1 kiloton underground nuclear explosion. The events occurred near a known coal mine that uses...
On 26 September, 2022 the International Monitoring System (IMS) detected two seismic events near the Danish island of Bornholm. The events were seen in both seismic and infrasound data and were located near the positions where large gas leaks from the North Stream were later observed. The events were furthermore recorded by seismographs in the surrounding countries and analysed at the National...
The Australian Radiation Protection and Nuclear Safety Agency (ARPANSA) maintains nine International Monitoring System (IMS) radionuclide stations across Australia, Antarctica, Fiji and Kiribati. A significant proportion of these are considered to be remote locations, where access is limited and local support is essential for the ongoing maintenance of the stations. This was particularly...
Landslides along the Inter-American Highway in Central Costa Rica, between San Ramon and Esparza are common, mostly during rainy season and are more related to instability due to the state of alteration of the materials on the slopes than to local faults. The saturation of the soil and the slopes could lead to the acceleration of these landslide processes even with earthquakes of moderate...
Previous works have demonstrated potential in using infrasound data to constrain earthquake source properties (Hernandez 2016; Shani-Kadmiel 2018, 2021; Averbuch 2020). Typically, the applied approaches are based on comparing modelled and recorded signals. In the current study we seek to constrain the source depth and moment-tensor. We use infrasound data from local and seismic data from local...
The IDA/GSN seismic network consists of 40 broadband seismic stations around the globe. Fifteen stations serve as auxiliary seismic stations of the International Monitoring System (IMS). During the COVID-19 pandemic, travel was severely disrupted. However, after considerable adjustment, network data return remained good and operational costs decreased. This was due to several factors: 1)...
The International Data Center (IDC) at the Comprehensive Nuclear-Test-Ban Treaty Organization routinely analyses data from radionuclide measurement stations of the International Monitoring System (IMS) in support of its mandate. The Standard Screened Radionuclide Bulletin (SSREB) is a product of the IDC that is generated for each radionuclide sample having measured concentrations of...
Two seismoacoustic events occurred on 26 September 2022 close to Bornholm Island in the Baltic Sea. Both events were listed in the Reviewed Event Bulletin of CTBTO as they were detected with the International Monitoring System. As the events were classified as a critical event by the Austrian National Data Centre, the available data were analysed in detail. The earlier event, with a published...
Xenon and iodine isotopes are, among other CTBT-relevant radionuclides, major indicators for nuclear explosions. They are therefore globally monitored by the International Monitoring System to verify compliance with the CTBT, using different technologies. Xenon isotopes are intermediate decay products of radioiodine. If originating from the same source, the radioxenon to radioiodine ratio of...
In the context of the Comprehensive Nuclear Test Ban Treaty (CTBT), the CEA/DAM developed the Système de Prélèvement Automatique en Ligne avec l'Analyse du Xénon (SPALAX) about 20 years ago which is used in the International Monitoring System to detect xenon releases following a nuclear explosion. The New Generation of the system has been successfully developed by the CEA and CEGELEC Défense....
We investigate historical nuclear tests from the Lop Nor region, China, using waveform-based source inversions and three-dimensional waveform modeling. Despite sparse data distributions and low signal-to-noise ratios, we recover isotropic moment tensor solutions for historical explosions and obtain detailed uncertainty information from likelihood evaluations over magnitude, depth, and the...
Sandia National Laboratories is developing the Geophysical Monitoring System (GMS) for modernization of the United States National Data Center waveform processing system. The United States is providing the common architecture and processing components of GMS as a contribution in kind to accelerate progress on International Data Centre (IDC) re-engineering. Open source releases of GMS,...
Radionuclide stations in the International Monitoring System (IMS) network routinely collect air samples and assess activity concentrations. Activities collected in samples are often caused by emissions from nuclear facilities, but they could also indicate a noble gas release from an underground nuclear explosion. A discrimination can be done by estimating and analysing activity ratios of...
Since 2008, the CTBTO has been conducting temporary radioxenon measurement campaigns using transportable systems. These campaigns are focused on improving the performance of the verification system as described in the Treaty. In 2017, the Government of Japan made a voluntary contribution to boost CTBTO capabilities to detect nuclear explosions. In early 2018, two transportable noble gas...
Seismological bulletins from local and regional seismic stations have identified signals associated with mining explosions in the Orapa mining area, Botswana. Here we present the results of integrating detections from regional seismic networks and the International Monitoring System (IMS) network. Using the local bulletins and catalogs, we requested IMS data via the Extended NDC-in-A- Box...
Data from the International Monitoring System (IMS) stations of the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) are being processed by automatic processing, Global Association, interactively analysed and reviewed, resulting in International Data Centre (IDC) bulletins. The Network Processing Vertically Integrated Seismic Analysis (NET-VISA) is a Bayesian seismic monitoring...
The National Data Centre of Côte d’Ivoire and the PTS installed a portable infrasound network (I68CI) from mid-January to December 2018 in the Comoé National Park located in north-east Côte d’Ivoire. This mobile station includes four sensors and use MB3d microbarometers with 50 Hz sampling frequency. The main objective of this one-year deployment is to better understand and characterize...
Immediate identification of system component failures through state of health (SOH) trend analysis allows for fast resolution of International Monitoring System (IMS) station issues. The Radionuclide Operations Support System (ROSS) allows staff of the Provisional Technical Secretariat to display station SOH data, assess current station performance, and notify International Data Centre...
The impact of wave propagation effects on the performance of the P/S ratio local discriminant is being evaluated during the third phase of the Source Physics Experiment, the Rock Valley Direct Comparison (RV/DC), conducted at the Nevada National Security Site. During the experiment a chemical explosion will be detonated near the hypocenter of a shallow earthquake. The direct waveform...
On 7 September 2017, the Democratic People’s Republic Korea carried out its latest and largest nuclear test (DPRK6). Recent efforts have been made to increase understanding of this and previous nuclear tests using seismic waveform, and synthetic aperture radar (SAR) geodetic deformation data (e.g. Wei 2017, Chiang et al. 2018, Myers et al. 2018, Wang et al. 2018). In our previous work...
On the Semipalatinsk Test Site territory there are several mineral deposits at some of which the active mining is observed. The most blasts are conducted at Karazhyra coal quarry. Three IMS stations, Makanchi (PS23), Borovoye (AS057), Kurchatov-Cross (AS058), are recording these quarry blasts. The quarry-to-stations distance is 452 km, 668 km, and 68 km respectively. For 19 years of...
In recent years there were several tragic accidents at military depots in the south of Kazakhstan (Arys, Taraz) and in Uzbekistan (Malik) resulting in destruction of buildings, injuries and loss. All these bursts were recorded by Kazakhstan seismic stations. The closest station to the epicenters of all bursts was Karatau seismic array, part of the National Nuclear Center monitoring system of...
When monitoring for potential underground nuclear tests, distinguishing shallow earthquakes from explosive sources can often be achieved using the ratio of the body-wave magnitude to the surface-wave magnitude (mb:Ms), as explosive sources often produce less energetic surface wave excitations than earthquakes with the same mb. Current methods for surface-wave detection at the International...
We introduce infrasound data products of all certified International Monitoring System infrasound stations for scientific studies and applications. We have reprocessed the IMS infrasound waveform data of the last 20 years using the Progressive Multi-Channel Correlation (PMCC) method, configured with one-third-octave frequency bands between 0.01 and 4 Hz. From the comprehensive detection lists...
The International Data Center is required to conduct expert technical analysis (ETA) and special studies to improve event parameters and assist States Parties in identifying the source of specific events, according to the Protocol to the Comprehensive Nuclear-Test-Ban Treaty. Source mechanism and event depth are two parameters which may be crucial for the event discrimination task. To...
Starting in 2010, when the OVSICORI-UNA seismic network was upgraded with 24-bit digitizers and broadband instruments, we selected possible candidates to GT5.0 seismic events from the seismic catalog.
The GENLOC program was used to locate the events and the selection criteria were as follows: 1) minimum number of stations greater than or equal to 30, 2) Gap less than 110 degrees, and 3)...
One of the tasks of the Provisional Technical Secretariat (PTS), in regards to the mandate of the International Monitoring System (IMS) Division, is to support, monitor and conduct maintenance activities. In this presentation an overview of the field missions that the CTBTO maintenance radionuclide team have performed after the pandemic restrictions were lifted will be given. These activities...
The Comprehensive Nuclear Test Ban Treaty (CTBT) prohibits nuclear explosions by anyone, anywhere: on the Earth's surface, in the atmosphere, underwater and underground by using four key technologies such as radionuclide monitoring. Niger deposited its instrument of ratification of the Comprehensive Nuclear Test Ban Treaty (CTBT) with the Secretary-General of the United Nations on 9 September...
Isotopic ratios of radioxenons can be used to verify the occurrence of an underground nuclear explosion (UNE). Simplified analytical models and closed-form solutions using Bateman equations simulate a idealized radioactive decay/ingrowth chain in a closed and well mixed system. The partitioning of the radionuclide inventory between a gas phase and rock melt created by the detonation and the...
For the purpose of monitoring for compliance with the Comprehensive Nuclear-Test-Ban Treaty (CTBT), the International Monitoring System (IMS) includes 80 sites with particulate radionuclide samplers, 40 of which also have a noble gas sensor system. The coincidence of radioiodine and radioxenon observations at the co-located systems may offer an opportunity for event screening. This study gains...
The Comprehensive Nuclear Test-Ban Treaty Organization (CTBTO) uses infrasound to measure acoustic impulses in the atmosphere that could be indicative of an atmospheric nuclear test or explosion. However, many other events analysed by analysts at the International Data Centre (IDC) and appear in IDC products such as the Reviewed Event Bulletin. Examples include gas pipeline explosions, rocket...
The National Data Center of Kyrgyzstan daily monitors seismic events of various nature, most of which are tectonic earthquakes and quarry blasts. Sometimes seismic stations in Kyrgyzstan register unusual phenomena associated with exogenous geological processes, such as landslides, snow avalanches, rockfalls and mudflows. Landslides and snow avalanches can be caused by both tectonic processes...
We determined root mean square (RMS) amplitudes of Lg waves from the six known underground nuclear tests conducted by the Democratic People’s Republic of Korea. We analysed waveform data from a dozen seismographic stations situated in the Republic of Korea, the People's Republic of China and the Russian Federation operated by the International Monitoring System, Global Seismic Network, and the...
The main purpose of this study consists in applying discrimination methods to distinguish known nuclear tests conducted by the Democratic People’s Republic of Korea from surrounding natural seismicity, based on various seismic signal processing algorithms. To characterize the Democratic People’s Republic of Korea's seismic activity between 2006 and 2022, spectral analysis, waveforms...
Over the past ten years of observations by the seismic monitoring network of the National Nuclear Center of the Republic of Kazakhstan, seismic events of a different nature have been registered on the territory of central Kazakhstan. The largest number of these events are quarry explosions at deposits of solid minerals. But there are also tectonic earthquakes and natural-technogenic events...
The Observatorio San Calixto (OSC) is the National Data Center for the Plurinational Bolivian State. It manages the certified seismic stations PS06-LPAZ, AS08-SIV and one infrasound array IS08-BO. The distances from our center to the far away seismic station is about 1000Km (AS08-SIV) and the other two are located at Altiplano where the environment to work is often hard. In order to obtain the...
This study provides an overview of a civil application of International Monitoring System (IMS) data to assist in disaster mitigation. Two infrasound arrays coupled with seismic stations of the IMS recorded the with Baltic Sea gas explosion on 26 September 2022. Underwater eruptions generate air waves and pressure waves that can cause fluctuations in the different layers of the atmosphere....
This work has the goal to present a useful method to help in the discrimination of natural events (tectonics) from artificial events (chemical explosions in quarries blasting) when both sources are co-located. This is a frequent problem where the seismicity is triggered by stress released due to material removal in mines. With that purpose, we are conducting experiments using local infrasound...
In this study we aim at discriminating hydroacoustic sources by identifying on the one hand source typical signal features derived from event catalogues and by characterizing on the other hand waveform similarities using clustering analyses of raw hydroacoustic data. We make use of event bulletins derived from the application of the Progressive Multi Channel Correlation method on International...
We introduce the Central and Eastern European Infrasound Network (CEEIN) established in 2018 as a collaboration between the Zentralanstalt für Meteorologie and Geodynamik, Vienna, Austria; the Institute of Atmospheric Physics of the Czech Academy of Sciences, Prague, Czech Republic; the Research Centre for Astronomy and Earth Sciences of the Eötvös Loránd Research Network, Budapest, Hungary;...
The International Monitoring System (IMS) of the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) comprises four verification technologies that work in synergy to enable the detection, location, and identification of potential nuclear explosions. One of the four technologies is the infrasound which listen to corresponding sound waves. As of 2022, Fifty-three from sixty planned IMS...
Paraguay, located in the middle of South America, is a low seismicity country. Nevertheless it has been collecting data for a long time. The continuous operation of the station gives us the opportunity to select several years of bulletin. This time five years of International Data Centre (IDC) detection (from 2018 to 2022) were selected from bulletins (reviewed and automatics) that are used to...
The Rock Valley Direct Comparison (RV/DC) project is the third phase of the Source Physics Experiment (SPE). Under RV/DC, two chemical explosions will be detonated near the hypocenters of a sequence of anomalously shallow earthquakes on the Nevada National Security Site. The explosions (nominally 1,000 and 10,000 kg TNT-equivalent) will be recorded by an extensive array of multi-physics...
The framework developed and presented here provides a new and transportable method to determine the yields of seismically recorded underground nuclear explosions. The key advantage of this method over other methods which estimate absolute explosive yields is that this method does not require any a priori calibration and can be immediately applied to any region of interest. This method uses the...
Impulsive, low frequency, electromagnetic signals were observed during historic United States underground nuclear tests. The source of these signals is uncertain though a prime candidate is the so-called “magnetic bubble”. This mechanism creates a magnetic signature when the hot plasma shell from the explosion expands in the Earth’s magnetic field. At low frequencies, this signal can diffuse...
Hundreds of years has elapsed since earthquakes started to be instrumentally recorded. However, our understanding of magmatic rifting and other complicated source features that we observe today was limited due to the absence of digital seismic records at epicentral distances of interest. After the advent of digital broadband instrumentation with wide dynamic range, volcano seismology has...
