NH8.1 | International Monitoring System and On-site Verification for the CTBT, disaster risk reduction and Earth sciences
EDI
International Monitoring System and On-site Verification for the CTBT, disaster risk reduction and Earth sciences
Convener: Martin Kalinowski | Co-conveners: Yan Jia, Christoph Pilger, Gérard Rambolamanana, Ole Ross
Orals
| Thu, 27 Apr, 16:15–18:00 (CEST)
 
Room 1.34
Posters on site
| Attendance Thu, 27 Apr, 14:00–15:45 (CEST)
 
Hall X4
Posters virtual
| Attendance Thu, 27 Apr, 14:00–15:45 (CEST)
 
vHall NH
Orals |
Thu, 16:15
Thu, 14:00
Thu, 14:00
The International Monitoring System (IMS) of the Comprehensive Nuclear-Test-Ban Treaty (CTBT) monitors the solid Earth, the oceans and the atmosphere with a global network of seismic, infrasound, and hydroacoustic sensors as well as detectors for atmospheric radioactivity. The primary purpose of the acquisition and analysis of IMS data is for nuclear explosion monitoring regarding all aspects of detecting, locating and characterizing nuclear explosions and their radioactivity releases. On-site verification technologies apply similar methods on smaller scales as well as geophysical methods such as ground penetrating radar and geomagnetic surveying with the goal of identifying evidence for a nuclear explosion close to ground zero.

Orals: Thu, 27 Apr | Room 1.34

Chairpersons: Ole Ross, Gérard Rambolamanana
16:15–16:25
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EGU23-1831
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ECS
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On-site presentation
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Erik Myklebust and Andreas Köhler

Automatic detection of seismic events in processing pipelines at the IDC and many NDCs is mostly done using beamforming on arrays; however, extensive use of single stations can improve the detection capability and accuracy of event location. Advances in deep learning methods enable faster and more accurate processing of large quantities of single station data not seen previously. We use event catalogues including phase picks on a range of arrays in Scandinavia at regional distances (200-2000km), i.e., up to 3min separation between P and S arrivals, to train several deep learning models (PhaseNet and EQTransformer variants) using single stations within the arrays. The models are trained on clips of 324s to capture the multiple arrivals. The models are then applied to various single stations in Norway to assess their generalization. We can detect events at a variety of back-azimuths and distances.  

Furthermore, we expand the existing deep learning models to provide predictions for back-azimuth and distance. This imposes physical restrictions on the models, leading to increased picking accuracy for the predicted phase arrivals. Moreover, this enables us to use the vast number of single stations available to efficiently detect and locate distant events.  

How to cite: Myklebust, E. and Köhler, A.: Regional phase picking on single stations using deep learning, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1831, https://doi.org/10.5194/egusphere-egu23-1831, 2023.

16:25–16:35
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EGU23-5603
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ECS
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On-site presentation
Andreas Steinberg, Peter Gaebler, and Christoph Pilger

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

How to cite: Steinberg, A., Gaebler, P., and Pilger, C.: Advantages and issues of applying Machine learning based denosing on inversions of the DPRK nuclear tests, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5603, https://doi.org/10.5194/egusphere-egu23-5603, 2023.

16:35–16:45
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EGU23-5497
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On-site presentation
Tine B. Larsen, Peter H. Voss, Trine Dahl-Jensen, Nicolai Rinds, Björn Lund, Peter Schmidt, Michael Roth, Gunnar Eggertsson, Andreas Köhler, Bettina Goertz-Allmann, Celso Alvizuri, Johannes Schweitzer, Volker Oye, and Christian Weidle

On September 26, 2022 the International Monitoring System (IMS) of the CTBTO detected two seismic events near the Danish island of Bornholm as reported in the Reviewed Event Bulletin (REB). In the REB phases include both seismic and infrasound data up to 1600 km away and the events are located near the positions where large gas leaks from the Nord Stream pipelines were also observed. The events were recorded clearly by the Danish seismograph network with the closest two seismographs located on Bornholm at distances of 40 – and 70 km. Furthermore, seismographs in the surrounding countries picked up the signals and data were analysed at the national data centers. The waveforms exhibited clear properties of underwater blasts with significant P-energy and much smaller S-energy, as well as other characteristics not associated with natural earthquakes. Further analysis revealed that the second event may consist of multiple blasts close in time and space. Analysis of the events included integration between IMS data and regional data from Denmark, Sweden, Germany and Norway, communication with CTBTO experts, and served as an exercise in collaboration during an international crisis.

How to cite: Larsen, T. B., Voss, P. H., Dahl-Jensen, T., Rinds, N., Lund, B., Schmidt, P., Roth, M., Eggertsson, G., Köhler, A., Goertz-Allmann, B., Alvizuri, C., Schweitzer, J., Oye, V., and Weidle, C.: Integrating IMS data in the analysis of the Nord Stream underwater blasts in the Baltic Sea, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5497, https://doi.org/10.5194/egusphere-egu23-5497, 2023.

16:45–16:55
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EGU23-6775
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On-site presentation
Björn Lund, Gunnar Eggertsson, Ari Tryggvason, Peter Schmidt, Michael Roth, Tine Larsen, Peter Voss, Trine Dahl-Jensen, Nicolai Rinds, Andreas Köhler, Bettina Goertz-Allmann, Celso Alvizuri, Johannes Schweitzer, Volker Oye, Christian Weidle, and Eric M. Dunham

Soon after midnight on 26 September 2022 the Swedish National Seismic Network, using data from Sweden, Denmark and Germany, automatically detected a seismic event in the Baltic southeast of the Danish island of Bornholm. The event was followed 17 hours later by a second, more complex, event northeast of Bornholm. The automatic locations of the events were within 6-9 km of later reported gas leaks in the Nord Stream 1 and 2 pipelines. Using recently developed, machine learning based, classifiers both events were automatically classified as explosions. Subsequent analysis of the second event revealed that it was in fact two blasts, separated by about 7 seconds. As the events occurred in the transition zone between the Fennoscandian Shield and the younger terranes of Denmark and northern Germany, 3D tomographic P- and S-velocity models were developed to improve locations and assess uncertainties, bringing the locations closer to the pipelines. Spectral analysis of the blast data show clear reverberations consistent with underwater explosions and a blast depth of approximately 75 m. The conclusion that the events are underwater blasts are further supported by data on known underwater explosions and a few earthquakes in the area. The magnitude of the first event was estimated at ML 1.9 and the combined second and third event had ML 2.3. Estimating the equivalent yield in the explosions is, however, non-trivial. Comparison to ground truth underwater explosions suggests yields of one to a few hundred kilos of equivalent TNT. The contribution to the seismic energy from suddenly outflowing methane gas is under investigation and results will be included in the presentation.

How to cite: Lund, B., Eggertsson, G., Tryggvason, A., Schmidt, P., Roth, M., Larsen, T., Voss, P., Dahl-Jensen, T., Rinds, N., Köhler, A., Goertz-Allmann, B., Alvizuri, C., Schweitzer, J., Oye, V., Weidle, C., and Dunham, E. M.: The Nord Stream underwater explosions: location, classification and yield estimation, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6775, https://doi.org/10.5194/egusphere-egu23-6775, 2023.

16:55–17:05
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EGU23-7019
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Virtual presentation
Andreas Köhler, Celso Alvizuri, Ben Dando, Bettina Goertz-Allmann, Johannes Schweitzer, Volker Oye, Björn Lund, Peter Schmidt, Michael Roth, Gunnar Eggertsson, Tine B. Larsen, Peter H. Voss, Trine Dahl-Jensen, Nicolai Rinds, and Christian Weidle

Two clear seismic events were observed on 26th September 2022 associated with the reported leaks from the Nord Stream 1 (Event 1, NE of Bornholm) and Nord Stream 2 pipelines (Event 2, SE of Bornholm). Arrivals of both events were detected and associated using data from several arrays in Norway and Finland, including the IMS stations NOA, FINES and ARCES. Additional signal analysis with data from the Swedish National Seismic Network and the Danish station on Bornholm enabled a third event to be identified. Auto-correlation analysis of the Event 2 revealed the third event (Event 2B) about 7 seconds after the main amplitude of the P onset (Event 2A). In contrast, for Event 1 SE of Bornholm no additional events could be identified from auto-correlation analysis, which increases confidence that these additional arrivals are not caused by interaction with geological structures. We also observe an arrival 7 s after the Pn phase before the Pg arrival on the NORES array. However, we cannot exclude that this onset interferes with the arrival of the PnPn phase. We then use the time differences between Event 2A and 2B measured by auto-correlation analysis on the Swedish and Danish network stations to determine relative epicentre locations. The results suggest that the two overlapping events occurred just about 220 m apart from each other. The relative locations fit very well with the distance between both pipelines of Nord Stream 1 at the Westernmost gas plume location (NE of Bornholm). We also estimated preliminary full moment tensors for Event 1 and 2 using seismic waveform data and analysed them on a source-type diagram. The results show positive isotropic parameters consistent with explosion-type mechanisms.

How to cite: Köhler, A., Alvizuri, C., Dando, B., Goertz-Allmann, B., Schweitzer, J., Oye, V., Lund, B., Schmidt, P., Roth, M., Eggertsson, G., Larsen, T. B., Voss, P. H., Dahl-Jensen, T., Rinds, N., and Weidle, C.: Relative locations and moment tensors of the Nord Stream pipeline events, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7019, https://doi.org/10.5194/egusphere-egu23-7019, 2023.

17:05–17:15
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EGU23-7053
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On-site presentation
Tiago Oliveira, Mario Zampolli, Dirk Metz, Georgios Haralabus, and Sergio Barrientos

In addition to monitoring the oceans for signs of nuclear explosions, the International Monitoring System (IMS) hydroacoustic data have been used for a broad range of civil and scientific applications, including the study of submarine earthquakes. This presentation analyzes T-wave signals recorded at CTBT-IMS hydrophone station HA03 triggered by Chilean earthquakes between 2014 and 2022. HA03 is located in the Juan Fernández Islands (Chile, South-East Pacific Ocean); in particular, the hydrophone arrays are located approximately 15 km north (H03N) and 15 km south (H03S) of Robinson Crusoe Island to account for the acoustic shadow produced by the islands. Arrival time and back azimuth of the recorded T-waves were estimated using the Dase ToolKit - Graphical Progressive Multi-Channel Correlation (DTK-GPMCC) program. Different arrivals within the duration of the earthquake signals were identified. However, discrepancies between expected and measured back azimuths can be observed for H03N and H03S. A three-dimensional underwater acoustic model was utilized to determine the cause of these differences. Based on the hydroacoustic arrivals identified for the analyzed earthquakes, a discussion is provided on the conversion from seismic to acoustic waves (T-waves generation zone). Moreover, reflected propagation paths induced by bathymetric features along the path from the T-waves generation zone to H03N and H03S are discussed.

How to cite: Oliveira, T., Zampolli, M., Metz, D., Haralabus, G., and Barrientos, S.: T-waves triggered by Chilean earthquakes recorded at CTBT-IMS station HA03, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7053, https://doi.org/10.5194/egusphere-egu23-7053, 2023.

17:15–17:25
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EGU23-7940
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On-site presentation
Infrasonic signals collected in the water column close to Svalbard
(withdrawn)
Christoph Waldmann and Christian Engler
17:25–17:35
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EGU23-12220
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On-site presentation
Robin Schoemaker, Jolanta Kusmierczyk-Michulec, Boxue Liu, Anne Tipka, Yuichi Kijima, Jonathan Bare, Martin Kalinowski, Christian Maurer, Paul Skomorowski, Alexander Hieden, Delia Arnold-Arias, Ramesh Sarathi, Brian Schrom, Jennifer Mendez, and Jerome Brioude

Radionuclide monitoring is one of the verification technologies of the global verification system of the Comprehensive Nuclear-Test-Ban Treaty (CTBT). This global network of sampling stations senses the air 24/7 for suspect noble gases and/or particulates. For noble gases this task is non-trivial due to the ever-present and highly variable background levels of the four radioxenon isotopes that are relevant for CTBT monitoring. An extensive, global effort was initiated to better estimate the civil radioxenon background based on known sources and end up with a more reliable event screening. This challenge, called “1st Nuclear Explosion Signal Screening Open Inter-Comparison Exercise 2021,” provided an assessment of a chain of multilevel, multidisciplinary scientific analyses and built on three previous atmospheric transport modelling (ATM) Challenges. It’s a first since it explored integrating both ATM and radionuclide statistical expertise to characterize the detection, time, location, and source strength of an anomalous event. The exercise ran through 2022 and was a collaboration between participants from around the world who utilized a comprehensive pre-developed test data set based on explosion release scenarios, xenon measurements and emission inventories, and atmospheric transport data provided by the ATM software FLEXPART. The data set was composed of synthetic activity concentrations of the simulated nuclear explosion signals added to the radioxenon measurements at the International Monitoring Station (IMS). Three levels of participation were offered, requiring different areas of expertise: 1) ATM expertise only, where participants simulated radioxenon background time series at the 23 IMS stations to be used as input for screening synthetic radioxenon measurements based on a set of predefined statistical methods; 2) radionuclide expertise, where participants provided their own methods and results for detection, screening, and timing powers; and 3) higher-level ATM and statistical expertise, where, in addition to Level 2, results were provided for location and magnitude estimates for a few selected test cases. This paper gives a general overview of the exercise and provides highlights and discusses the key results.

How to cite: Schoemaker, R., Kusmierczyk-Michulec, J., Liu, B., Tipka, A., Kijima, Y., Bare, J., Kalinowski, M., Maurer, C., Skomorowski, P., Hieden, A., Arnold-Arias, D., Sarathi, R., Schrom, B., Mendez, J., and Brioude, J.: Advancing the Support to the Radionuclide Monitoring Verification Technology of the CTBT with the 1st Nuclear Explosion Signal Screening Open Intercomparison Exercise 2021, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12220, https://doi.org/10.5194/egusphere-egu23-12220, 2023.

17:35–17:45
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EGU23-7517
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On-site presentation
Emilia Koivisto, Luis R. Gaya-Pique, Aled Rowlands, Remi Colbalchini, Samuel Toon, and Peter Labak

On-site inspection (OSI) is the final verification measure of the Comprehensive Nuclear-Test-Ban Treaty (CTBT). According to paragraphs 69(e), 69(f) and 69(g) of Part II of the Protocol to the CTBT, an OSI may involve the following seismic and non-seismic geophysical techniques to search for, locate and characterize underground anomalies associated with a nuclear explosion: passive seismological monitoring for aftershocks; resonance seismometry and active seismic surveys; magnetic and gravitational field mapping; ground penetrating radar; and electrical conductivity measurements. In this presentation we review recent advances in development of OSI geophysical techniques, with a focus on the application of techniques in challenging mountainous environments. Previously, techniques were primarily tested in relatively flat or gently undulating terrain conditions.

Most recent advances in passive seismological monitoring include the upgrade of the telemetry system for data transmission and development of the data processing software to accommodate topographically challenging environments. To assess current OSI geophysical imaging capabilities for the other geophysical techniques and for deep site characterization applications in an integrated manner, an extensive OSI field test was conducted in the Austrian Ybbstaler Alps in September 2022. This was the first OSI field test in a challenging mountainous environment. Therefore, a number of operational, logistical and technical challenges had to be addressed. The implemented OSI geophysical techniques included resonance seismometry (passive seismic imaging) and active seismic surveys, magnetic and gravitational field mapping, as well as electrical conductivity measurements along three profiles over a cave system at 40-350 m depths mimicking underground cavities produced by an underground nuclear explosion. A newly acquired active seismic data recording system was tested for the first time, with the aim to mature OSI methods for active seismic surveys. Prior to this field test active seismic surveys have only been applied in a limited capacity. A recently developed concept of operations for resonance seismometry was also tested. Furthermore, based on the results of the field test, a new OSI workflow for gravitational field mapping is being developed. During the field test, full OSI data workflow for geophysical techniques was implemented using current functionalities within the Geospatial Information Management system for OSI (GIMO).

Overall, these recent advances in development of OSI geophysical techniques demonstrate the applicability of the full range of OSI geophysical techniques in mountainous terrain, and results of these projects will be used to further develop the geophysical techniques for challenging environments.

How to cite: Koivisto, E., Gaya-Pique, L. R., Rowlands, A., Colbalchini, R., Toon, S., and Labak, P.: Advances in development of OSI geophysical techniques for mountainous environments, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7517, https://doi.org/10.5194/egusphere-egu23-7517, 2023.

17:45–17:55
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EGU23-8763
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On-site presentation
Lars Ceranna and the InfraAUV-Project-Team

Metrology – the science of measurement – has an important role in all fields of science and technology. Core concepts of measurement traceability and measurement uncertainty are vital for measurements to be physically meaningful and for data to be quantified with known levels of confidence. Metrology considerations begin with primary measurement standards; the definitive realisation of a particular quantity that underpins all subsequent measurements of that quantity. Primary standards for sound pressure and acceleration have long been established but historically, have not extend to the relevant frequency ranges in many geophysical applications utilizing seismic, infrasonic, and hydroacoustic technologies, including IMS applications. A European research project called Infra-AUV has recently developed new primary measurement standards for infrasound and for low-frequency seismic measurements, as well as the means to transfer these to enable the calibration of sensors in the field, as required at stations in the IMS network. New calibration capabilities and application-focussed case studies emerging from the Infra-AUV project will therefore be presented, together with the potential consequences and benefits for users of such sensor systems. 

How to cite: Ceranna, L. and the InfraAUV-Project-Team: Infra-AUV Project – Provision of measurement traceability for sound and vibration measurements in the very low frequency range., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8763, https://doi.org/10.5194/egusphere-egu23-8763, 2023.

17:55–18:00

Posters on site: Thu, 27 Apr, 14:00–15:45 | Hall X4

Chairpersons: Christoph Pilger, Yan Jia
Nuclear Explosion Monitoring
X4.53
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EGU23-16259
Haijun Wang, Gerard Rambolamanana, Gerhard Graham, Ronan Le Bras, Paulina Bittner, Tea Mumladze, Ali Kasmi, Ali Sherif Mohamed, Ehsan Chegeni Ehsan, Marcela Villarroel, David Applbaum, Mariia Makhonina, and Jimenez Aaron Joseph Gutierrez

As of 14 December 2020, almost 90% of the IMS facilities (including radionuclide laboratories) were built and certified, data is transmitted in either real-time or on request from IMS stations to IDC for processing and analyzing. IDC analysts review automatic bulletins generated continuously and release the Reviewed Event Bulletin (REB) on a daily basis since February 2000. We present the statistics of mostly natural seismicity waveform events processed and analyzed over the past 20 years, as the network grew in size and became established. Multiple parameters including magnitude for those events associated with detections from seismic, hydroacoustic and infrasonic stations are analyzed. Techniques and rules related to waveform data analysis and the need to correct the automatic bulletin are discussed. This discussion should be beneficial for analysts work and data processing system optimization.

How to cite: Wang, H., Rambolamanana, G., Graham, G., Le Bras, R., Bittner, P., Mumladze, T., Kasmi, A., Mohamed, A. S., Chegeni Ehsan, E., Villarroel, M., Applbaum, D., Makhonina, M., and Joseph Gutierrez, J. A.: Twenty years of IDC Reviewed Event Bulletin (REB) statistics using data from a sparse IMS network to one reaching near completion, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16259, https://doi.org/10.5194/egusphere-egu23-16259, 2023.

X4.54
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EGU23-14132
Cem Destici, Korhan Şemin, Serdar Koçak, and Haluk Özener

Bogazici University-Kandilli Observatory and Earthquake Research Institute (KOERI) is operating IMS Primary Seismic Station (PS-43) under Belbasi Nuclear Tests Monitoring Center for the verification of compliance with the Comprehensive Nuclear-Test-Ban Treaty (CTBT) since February 2000. PS-43 is composed of two seismic arrays (Ankara and Keskin). The medium-period array equipped with Guralp CMG-3TB instruments is located in the capital city of Ankara whereas the short-period array with Geotech 23900 sensors is located in Keskin. The data quality of the some of the array elements are degraded by the quarry blasts especially if there is an earthquake occurred at the same time with the explosion. There are more than 10 operational stone quarries spread across the city and there are more applications for new quarries each year. In this study, we show the importance of monitoring the quarry activities for the operation of the Turkish NDC. For this purpose, each blast is detected by automatically using cross-correlation and confirmed manually by the analyst.

How to cite: Destici, C., Şemin, K., Koçak, S., and Özener, H.: Monitoring and Data Quality Issues of Mining Activites Around BRTR, Turkiye, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14132, https://doi.org/10.5194/egusphere-egu23-14132, 2023.

X4.55
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EGU23-10667
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ECS
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Jinyin Hu, Thanh-Son Phạm, and Hrvoje Tkalčić

A seismic moment tensor (MT, a 3x3 matrix) is a general source representation of various seismic events under the point source assumption, which is generally valid for small-to-medium size earthquakes. A full MT can be decomposed into isotropic (ISO), compensated linear vector dipole (CLVD), and double-couple (DC) components. The ISO represents the explosion/collapse source process that involves volumetric changes. Therefore, the relative significance of the ISO component, which can be learned from inverting seismic waveforms, is an essential indicator to discriminate between earthquakes and explosive events. However, an intrinsic ISO-CLVD tradeoff impedes resolving shallow explosive sources due to the high similarity of long-period waveforms at regional distances. Even though this tradeoff can be mitigated by extra constraints such as teleseismic P-waves, there is still an urgent need for advanced inversion algorithms to explore the solution space thoroughly. Apart from that, a rigorous uncertainty estimate is required to constrain the source better. Firstly, the inversion should consider the data noise. Secondly, the theory error primarily due to imperfect knowledge of Earth's structure is also significant but proven difficult to treat. Here, we propose a new Bayesian MT inversion scheme with affine-invariant ensemble samplers to explore the MT parameter space accounting for data and theory errors. Carefully designed synthetic experiments indicate the advantage of the newly developed method in resolving the isotropic components of a shallow seismic source. Our application to DPRK tests reveals a similar source mechanism dominated by a high ISO and significant CLVD components, including a small DC component. This study aims to characterize shallow explosive sources' physics better, thus helping verify compliance with the CTBT.  

How to cite: Hu, J., Phạm, T.-S., and Tkalčić, H.: Characterizing Isotropic Source Component of DPRK Nuclear Tests by Affine-invariant Bayesian Samplers with Uncertainty Estimate for Data Noise and Theory Error, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10667, https://doi.org/10.5194/egusphere-egu23-10667, 2023.

X4.56
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EGU23-13272
J. Ole Ross, Peter Gaebler, and Lars Ceranna

Various techniques of Atmospheric Transport Modelling were applied after the announced nuclear tests conducted by the DPRK 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.

The presentation gives a comprehensive overview how ATM supported the analysis within the German NDC for all six nuclear test explosions announced by the DPRK.  It is particularly in focus 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) indicating strong evidence for the actual nuclear fission event.

How to cite: Ross, J. O., Gaebler, P., and Ceranna, L.: Atmospheric Transport Modelling for potential releases and detections of radioxenon possibly connected with nuclear test explosions conducted in North Korea, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13272, https://doi.org/10.5194/egusphere-egu23-13272, 2023.

X4.57
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EGU23-3411
Martin Kalinowski

This presentation summarizes the currently best available estimates of radioxenon emissions from all nuclear facilities for a specific year. It is a unique data set to be used in studies to enhance data analysis from the noble gas component of the International Monitoring System (IMS). Global radioactivity monitoring for the verification of the Comprehensive Nuclear-Test-Ban Treaty (CTBT) includes the four xenon isotopes 131mXe, 133Xe, 133mXe and 135Xe. These four isotopes are serving as important indicators of nuclear explosions. The state-of-the-art radioxenon emission inventory uses generic release estimates for each known nuclear facility. However, the release amount can vary by several orders of magnitude from year to year. The year 2014 was selected for a single year radioxenon emission inventory with minimized uncertainty. Whenever 2014 emissions reported by the facility operator are available these are incorporated into the 2014 emission inventory.

This presentation summarizes this newly updated radioxenon emission inventory. It comprises all relevant nuclear facilities. For the three strong sources ANSTO (Australia), CNL (Canada), and IRE (Belgium), stack release data with a high time resolution are available. Annual emissions are provided for all other medial isotope production facilities, including new updates for the NIIAR facility (Russia) and the Karpov Institute (Russia). For nuclear power plants (NPP) in Europe and the USA the reported release for the whole year is applied in combination with information about their operational schedule. For all other NPPs the best estimates are used. The estimated releases of nuclear research reactor sources are included as well. For the first time, estimates were made for radioxenon releases from spallation neutron sources and from spent nuclear fuel reprocessing plants. The new emission data are compared with previous studies highlighting discrepancies which in many cases are as large as several orders of magnitude.

The global radioxenon emission inventory for 2014 can be used for studies to estimate the contribution of this anthropogenic source to the observed ambient concentrations at IMS noble gas sensors to support CTBT monitoring activities, including calibration and performance assessment of the verification system as described in the Treaty as well as developing and validating methods for enhanced detection capabilities of signals that may indicate a nuclear test. One specific application is the 1st Nuclear Explosion Signal Screening Open Inter-Comparison Exercise that was announced end of 2021 and conducted in 2022. The emission inventory in combination with radioxenon observations at IMS stations may as well be used for global or regional atmospheric tracer studies and for the validation of atmospheric transport simulation methods.

How to cite: Kalinowski, M.: Updated global radioxenon emission inventory from all types of nuclear facilities specific for the year 2014, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3411, https://doi.org/10.5194/egusphere-egu23-3411, 2023.

Traceable Calibration of Acoustic, Underwater and Vibration Sensors
X4.58
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EGU23-7953
Dominique Rodrigues, Paul Vincent, Richard Barham, and Franck Larsonnier

Demand for calibration at infrasonic frequencies has emerged. It is supported by earth monitoring issues and particularly by the Comprehensive nuclear Test Ban Treaty Organization (CTBTO), which provides a global international coverage for nuclear testing ban, and requires for the IMS (International Monitoring System). In the presentation, a new laser pistonphone design is presented with the objective of establishing primary standards for sound pressure at very low frequencies down to 10 mHz. The piston is a modified accessorized loudspeaker driver whose diameter is equal to the diameter of the front pistonphone cavity. The volume velocity of the piston is measured through a laser interferometer and it was designed to have an upper frequency limit of 20 Hz, to overlap with the reciprocity method of calibration. Particular attention has been given with the-sealing to avoid the pressure leakage loss. The dimensions of the front cavity were designed to allow the calibration of a large variety of sensors, including microphones, barometers, manometers and microbarometers. Examples of calibrations for several sensors are presented with the uncertainty. Finally, the metrological performance of the laser pistonphone is demonstrated by comparing the calibration results with those obtained with alternative methods.

How to cite: Rodrigues, D., Vincent, P., Barham, R., and Larsonnier, F.: A laser pistonphone designed for absolute calibration of infrasound sensors from 10 mHz up to 20 Hz, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7953, https://doi.org/10.5194/egusphere-egu23-7953, 2023.

X4.59
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EGU23-13793
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Erling Sandermann Olsen

For many years, primary measurement standards of sound pressure have been realized by calibration of laboratory standard, LS, microphones with the reciprocity calibration technique specified in international standard IEC 61094-2. Recent BIPM key comparisons, CCAUV.A-K5 and CCAUV.A-K6, have extended the lower frequency limit of the method from 20 Hz to 2 Hz, but with known uncertainty on the standard’s models of thermos-viscous effects and acoustic impedance of the microphones, which in practice prevented further excursion to lower frequencies. This uncertainty has now been minimized with improved calculation methods that have been included in an amendment to the standard, IEC 61094-2 AMD1. These developments have opened the possibility of reducing significantly the lower frequency limit of the method, subject to practical considerations.

A significant advantage of extending the frequency range of the reciprocity technique to the low frequencies targeted in the Infra-AUV project is that it will enable one primary method to cover the entire frequency range of pressure sensitivity from quasi-static pressure variations at 40 mHz, or lower, to 10 kHz for LS1 (one-inch LS) microphones.

With the reliable calculations of the acoustic properties of air in cylindrical cavities at low frequencies now available, the dominating challenge of extending the reciprocity technique to frequencies below 2 Hz has been to ensure a very low, and at the same time highly reproducible, cut-off frequency of the necessary static pressure equalization of the cylindrical cavities, couplers, used in the calibrations. Prototype couplers have been developed in the project that solves this challenge. The achieved reproducibility of reciprocity calibrations at frequencies down to 25 mHz and some independent verification of the results will be presented.

How to cite: Olsen, E. S.: Extension of reciprocity calibration of microphones to frequencies below 1 Hz, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13793, https://doi.org/10.5194/egusphere-egu23-13793, 2023.

X4.60
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EGU23-13437
Christoph Kling, Marvin Rust, and Christian Koch

The reliable and comparable assessment of any physical quantity requires traceability to the international system of units (SI). Sound pressure is traditionally quantified using measurement microphones as transfer standards, for which the established primary calibration methods are currently limited to frequencies of 2 Hz and higher. These frequencies do not fully cover the range of interest for the International Monitoring System (IMS). For this reason, multiple calibration methods for airborne infrasound based on different physical principles are currently in development.

In this poster, a primary calibration method for the realization of the unit Pascal and a secondary calibration method for the transfer of the unit to field devices are presented. The primary calibration method utilizes the vertical gradient of the ambient pressure as stimulus. Moving a microphone periodically up and down subjects it to an alternating pressure with calculable amplitude. The secondary calibration, which transfers the unit to field devices such as microbarometers, is conducted as a comparison calibration in a closed chamber. Both the reference microphone and a device under test are placed in a closed chamber and subjected to a low-frequency alternating pressure. The sensitivity of the device under test is determined by comparison to the reference.

These methods extend the frequency range for the calibration of sensors for airborne infrasound to lower frequencies and improve the reliability of the assessment of airborne infrasound. In this contribution, the capabilities and limitations of both measurement setups are discussed.

How to cite: Kling, C., Rust, M., and Koch, C.: Calibration of sensors for airborne infrasound utilizing the hydrostatic pressure gradient, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13437, https://doi.org/10.5194/egusphere-egu23-13437, 2023.

X4.61
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EGU23-5620
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ECS
Freya Malcher, Ben Ford, Richard Barham, Can Çorakçi, Alper Biber, Stephen Robinson, Sei-Him Cheong, Justin Ablitt, and Lian Wang

Low frequency Acoustics, Underwater Acoustics and Vibration (AUV) phenomena in water are used to detect major natural events such as earthquakes, tsunamis and volcanic activity, and are also used by the International Monitoring System (IMS) of the Comprehensive Nuclear-Test-Ban Treaty Organisation (CTBTO) to check compliance with the treaty. Low frequency sound and vibration monitoring technologies are well established; however the lowest frequencies of interest are not sufficiently well covered by current measurement standards, limiting the reliability of data obtained. In addition, monitoring stations are also often located in extreme environments posing additional challenges for assuring the accuracy of measurements recorded by hydrophones. In this poster we describe the work that NPL, TUBITAK and ASN are doing in the Infra-AUV project to develop calibration methods for hydroacoustics in the frequency range from 0.5 Hz to 100 Hz.

The project is establishing both primary standards (based on absolute realisations of the acoustic pascal), and secondary comparison methods to provide routes for effective dissemination and traceability. Two independent primary calibration methods are under development. The first uses a laser pistonphone (NPL and ASN) which uses optical interferometry to determine the motion (and therefore the generated pressure) of a piston driving a small chamber containing the hydrophone under test. The second is the coupler reciprocity method (TUBITAK and NPL) which allows hydrophones to be calibrated in more realistic ocean conditions (increased static pressure). Secondary calibration methods have been developed based on comparison of two devices in a small coupler (NPL and TUBITAK). The resulting calibration capability will underpin new measurement services and improve traceability in low frequency sound measurement and monitoring applications.

How to cite: Malcher, F., Ford, B., Barham, R., Çorakçi, C., Biber, A., Robinson, S., Cheong, S.-H., Ablitt, J., and Wang, L.: Low-frequency standards for hydroacoustics in the Infra-AUV project, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5620, https://doi.org/10.5194/egusphere-egu23-5620, 2023.

X4.62
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EGU23-13404
Leonard Klaus, Franck Larsonnier, Jacob Holm Winther, Michaela Schwardt, Michael Kobusch, and Thomas Bruns

At present, seismometers are not traceably calibrated. This means that their output sensitivity is not determined in a way that is traceable to the International Systems of Units (SI). The European research project 19ENV03 Infra-AUV, which is part of the EMPIR programme, develops methods and procedures to enable such traceable calibrations.

In contrast to many other sensors, seismometers are operated stationary in their typical measurement application, i.e., they must not be moved after their deployment. Conventional calibration approaches which involve a laboratory calibration of the seismometer to be calibrated are therefore not feasible. For this reason, a new concept currently developed by different European partners within the Infra-AUV project proposes an on-site calibration scheme.

For the on-site calibration, a reference seismometer is traceably calibrated to the SI in a laboratory. This reference is then used on-site to provide a secondary calibration of other seismometers, e.g. in a seismic station, using natural excitation sources [Schwardt et al., 2022, DOI: 10.1007/s10712-022-09713-4].

The calibration of reference seismometers in the laboratory is carried out as a primary calibration. This means that the measured quantity (the velocity-proportional voltage output) is compared to a different quantity, in this case to a dynamic displacement measurement traced back to the units length and time, which can be measured very precisely by laser interferometry. In this calibration, the seismometer is excited with low-frequency mechanical vibrations generated by electrodynamic exciters. These calibrations must be performed for the horizontal and vertical axes. The frequency range of interest is from 20 Hz down to 0.01 Hz, depending on the seismometer under test. Either mono-frequency sinusoidal excitations of different frequencies are applied subsequently, or multiple frequencies are excited simultaneously using a multi-sine approach. The magnitudes and phases of both measured signals, the interferometric reference and the seismometer under test, are determined by using sine approximation algorithms or by applying a discrete Fourier transform (DFT).

The results of the laboratory calibration, the transfer function of the reference seismometer, can then be derived from the ratios of the measured magnitudes and the differences of the phase angles for the different excitation frequencies. In addition, the associated measurement uncertainties are estimated and are part of the calibration result. Influences that may change the sensitivity of a seismometer, e.g., temperature effects, electromagnetic sensitivity, or ground stiffness need to be analysed and additionally taken into account for the uncertainty estimation.

For the uncertainty of the on-site calibration, differences between the laboratory and the on-site environment also need to be taken into account. This includes, for example, aspects like typically different temperatures or different ground materials.

How to cite: Klaus, L., Larsonnier, F., Winther, J. H., Schwardt, M., Kobusch, M., and Bruns, T.: Traceable Calibration of Seismometers, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13404, https://doi.org/10.5194/egusphere-egu23-13404, 2023.

X4.63
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EGU23-8100
Richard Barham, Dominque Rodrigues, Franck Larsonnier, Michaela Schwardt, Ben Ford, and Freya Malcher

Transfer standards have an important role in calibration, in enabling traceability to be transferred across calibration facilities or physical locations. It is often the case in laboratory calibration, that the sensors best suited to achieving the optimum calibration accuracy, or measurement uncertainty, have different characteristics to those that need to be deployed in the field. Laboratory calibration techniques are often tailored to work with sensors of a specific type or form factor, and requirements on ruggedness and tolerance of a wide range of environmental conditions are usually of lesser importance under laboratory conditions. Conversely, a transfer standard is ideally suited to both laboratory and field environments. The Infra-AUV project is developing a complete calibration-chain solution to establish measurement traceability for IMS measurements, and consideration has therefore been given to the specification of suitable transfer standard sensors. The thought process behind this, and the infrasound sensors, hydrophones and seismometers ultimately proposed for designation as transfer standards will be presented, together with some characteristic calibration data.

How to cite: Barham, R., Rodrigues, D., Larsonnier, F., Schwardt, M., Ford, B., and Malcher, F.: Transfer standard sensors for disseminating traceable calibrations to the field, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8100, https://doi.org/10.5194/egusphere-egu23-8100, 2023.

X4.64
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EGU23-11059
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ECS
Michaela Schwardt, Christoph Pilger, Samuel Kristoffersen, Franck Larsonnier, Leonard Klaus, Thomas Bruns, and Lars Ceranna

As part of the joint research project "Metrology for low-frequency sound and vibration - 19ENV03 Infra-AUV" laboratory calibration methods for seismometers and microbarometers in the low frequency range down to 0.01 Hz have been developed. These procedures provide the possibility of traceable on-site calibration during operation for field sensors of the Comprehensive Nuclear-Test-Ban Treaty Organization’s (CTBTO) International Monitoring System (IMS). The traceable calibration allows for accurate amplitude and phase information as well as for an assignment of uncertainties in amplitude and phase. Thereby, data quality and the identification of treaty-relevant events is improved. The on-site calibration procedure requires a reference sensor with a precise and traceable response function which is provided by the newly developed laboratory calibration methods, as well as the record of sufficient coherent excitation signals within the relevant frequency range. The reference sensors can be installed as transfer standards co-located to the operational IMS station sensors without disturbing their regular measurements for treaty validation purposes.

At IMS stations PS19 and IS26 in Germany we performed on-site calibration tests with both seismometers and microbarometers calibrated in the laboratories at PTB and CEA, respectively, using signals from different natural and anthropogenic excitation sources. Following the approach of Gabrielson (2011) with modifications from Charbit et al. (2015) and Green et al. (2021), the gain ratio between the station sensor under test and the reference sensor is calculated. By multiplying the gain ratio with the precise frequency response of the reference, the frequency response function for both magnitude and phase of the station sensors including site-specific factors such as the wind noise reduction system or possible effects of pre-amplifiers and data loggers are determined.

We present calibration results derived from the comparison of IMS station sensors with the laboratory-calibrated instruments along with the nominal responses. The results show agreement with deviations of less than 5% from the nominal response function for frequencies below 10 Hz for all components. The traceable determination of the response for the individual components in detail improves the sensor quality; subsequently waveform amplitudes can be estimated correctly.

How to cite: Schwardt, M., Pilger, C., Kristoffersen, S., Larsonnier, F., Klaus, L., Bruns, T., and Ceranna, L.: Determination of the frequency response of seismic and infrasonic IMS station sensors using a traceable on-site calibration approach, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11059, https://doi.org/10.5194/egusphere-egu23-11059, 2023.

X4.65
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EGU23-6393
Christoph Pilger and Michaela Schwardt

In the context of the joint research project "Metrology for low-frequency sound and vibration - 19ENV03 Infra-AUV" we evaluated natural, anthropogenic and controlled sources of seismic, infrasonic, and hydroacoustic waves with respect to their potential use as excitation signals for on-site calibration of the respective sensors in the range of 0.01 to 20 Hz. In that context, man-made controlled sources such as drop weights, hammer blows or vibrator sources exhibit properties such as broad frequency content and high repeatability that make them an interesting source signal for the calibration of seismometers.

At IMS station PS19 in Germany we conducted an excitation experiment using both a portable electrodynamic seismic vibrator source and simple hammer blows on the ground for the purpose of covering the higher frequencies of interest from 8 to 20 Hz and above for on-site seismometer calibration. As previous on-site calibration experiments have shown, insufficient coherent natural excitation signals within the relevant high frequency range have been recorded, leading to missing information in the frequency response estimation. Using the seismic vibrator source either P- or S-waves could be excited for example as monofrequent (18 Hz) or sweep (10-100 Hz) signals of 10 s time duration. The distance between excitation source and station/reference sensors as well as the direction of signal arrival at the sensors was varied.

We present calibration results for the conducted excitation experiment using a comparison between station and laboratory-calibrated instruments, showing that the frequency response can be determined for the higher frequencies of interest using the different signals from the excitation experiment.

How to cite: Pilger, C. and Schwardt, M.: Application of controlled vibration sources for traceable on-site calibration of seismometers, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6393, https://doi.org/10.5194/egusphere-egu23-6393, 2023.

X4.66
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EGU23-7525
Paul Vincent, Samuel Kristoffersen, Alexis Le Pichon, and Benoit Alcoverro

Infrasound stations, including those of the International Monitoring System (IMS) as part of the Comprehensive Nuclear Test-Ban Treaty Organization (CTBTO), are used to determine the location of infrasound sources (such as earthquakes, volcanoes, explosions etc.). The triangulation of these sources is done by considering the delay of the arrival times of the signal using several detectors at precisely known locations in an array with an aperture of typically a few kilometers. It is, therefore, of great importance that the amplitude and, especially, the phase of the signal at each sensor in the array is precisely known. Although the calibration of microbarometers can be performed in a laboratory setting, it is much more difficult to determine the transfer function of the wind noise reduction systems (WNRS), designed to reduce the wind associated noise. In-situ calibration of these WNRS’s can be performed using a co-located reference sensor, and comparing the response to that of the array sensor (considering only highly coherent signals) to determine the relative response of the WNRS. System defects, such as flooded pipes or blocked inlets, have significant impacts on the response of the WNRS, and are therefore of interest for the infrasound community. Comparisons between models of these defective WNRS’s and experimental results will allow for the characterization of these effects on the measurements and improvements of the models and WNRS designs. The results of these calibration and WNRS defect experiments will be presented, and compared with models.

How to cite: Vincent, P., Kristoffersen, S., Le Pichon, A., and Alcoverro, B.: A study of defects on infrasound Wind-Noise-Reduction Systems (WNRS) using in-situ calibration, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7525, https://doi.org/10.5194/egusphere-egu23-7525, 2023.

Posters virtual: Thu, 27 Apr, 14:00–15:45 | vHall NH

Chairperson: Martin Kalinowski
vNH.2
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EGU23-8287
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ECS
Andrius Puzas, Christian Bernhardsson, Guillaume Pédehontaa-Hiaa, Mattias Jönsson, Sören Mattsson, Nikolaj Tarasiuk, Marina Konstantinova, Rasa Gvozdaite, Ruta Druteikiene, Vida Juzikiene, and Vidmantas Remeikis

Detection of environmental concentrations of radionuclides is the next step to complement data on abnormal events recorded by seismic, hydro-acoustic and infrasound station networks prior to asking for the approval of the on-site inspection. Radionuclides can travel hundreds of kilometres away from their source and under favourable meteorological conditions, be detectable in the air and when deposited on the ground. In order to determine and assess contributions to the anthropogenic radionuclides in the environment and to firmly distinguish it from previous global nuclear tests or emissions from nuclear facilities, it is essential to screen the background “zero point” of the anthropogenic radionuclides. This is especially important around existing sources e.g. nuclear power plants. In this work the radiochemical separation of radionuclides, alpha-, gamma- and mass-spectrometry measurement techniques were combined to determine concentrations and compositions of anthropogenic radionuclides in soil samples within 70 km radius around the Belarussian nuclear power plant in Astravec, on the territory of Lithuania. Gamma spectrometric measurements were performed with state-of-the-art alpha spectrometers and gamma spectra were acquired using an HPGe coaxial detector. Radionuclide isotopic ratios were measured by a sector field mass spectrometer combined with a high-sensitivity APEX sample introduction system. In this work 137Cs/239,240Pu, 238Pu/239,240Pu, 240Pu/239Pu isotopic “fingerprint” values revealed that previous nuclear weapon tests in the Northern hemisphere are prevailing in most of the sampling sites within a 70 km radius around Astravec NPP on the Lithuania territory.

How to cite: Puzas, A., Bernhardsson, C., Pédehontaa-Hiaa, G., Jönsson, M., Mattsson, S., Tarasiuk, N., Konstantinova, M., Gvozdaite, R., Druteikiene, R., Juzikiene, V., and Remeikis, V.: “Zero Point” Background Screening of 137Cs and Pu isotopic composition for radiation environment in Eastern Lithuania, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8287, https://doi.org/10.5194/egusphere-egu23-8287, 2023.

vNH.3
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EGU23-10471
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ECS
Matthew Paul, Guangping Xu, Matthew Powell, Gavin Hearne, and Jeffery Greathouse

Detection of radioisotopes of noble gases produced by nuclear detonations is one of the methodologies employed by the Comprehensive Nuclear-Test-Ban Treaty. Whereas noble gases are chemically inert, adsorption of pure noble gases has been reported to exhibit non-conservative behavior in naturally occurring nanoporous minerals, albeit under idealized single-component laboratory conditions. Extrapolation of single-component gas adsorption measurements to the multi-component ambient environment that is predominately nitrogen and oxygen, but importantly water, requires numerous assumptions and introduces uncertainty.

This work aims to experimentally examine multicomponent adsorption of Ar, Kr, and Xe on zeolitic materials using an adaptation of the volumetric method. In the most generic sense, the volumetric method measures porosity and gas adsorption by expanding a reference volume of gas to a sample material and the change on the resulting pressure of the system. To apply this method to a multicomponent system where different species are different in the amount of adsorption and speed, it is necessary to monitor the composition of the gas phase in addition to total pressure. In this work, gas composition is monitored using a quadrupole mass spectrometer continuously, enabling Ar, Kr, and Xe to be measured concurrently.

Tests were first conducted on natural clinoptilolite samples which were vacuum-dried and then were exposed to dry air. Relatively little Ar is adsorbed under all conditions tested. However, the heavier noble gases Kr and Xe continue to exhibit significant adsorption effects in vacuum-dried clinoptilolite, despite the overwhelming abundance of nitrogen and oxygen. When the samples were additionally exposed to wet air with different humidity levels, the quantity of Kr and Xe adsorbed was significantly reduced. However, while the quantity of Xe adsorbing was most significantly reduced between 0% to 8 % relative humidity, non-negligible Kr adsorption persisted up to at least 55% relative humidity, the highest humidity level tested. As Kr continued to adsorb, albeit to a lesser degree, but Xe did not, this indicates the reduction in noble gas adsorption is not simply a function of surface coverage. To further explore this phenomenon, additional zeolitic materials, both pure mineral phases and heterogenous rock samples, will be examined.

As this work shows that water can not only to decrease the total adsorption significantly but also can potentially differentiate gas compositions. Consequently, the scenarios where radioactive noble gases can be modeled as being conservative tracer gases may vary with both environmental conditions as well as subsurface geology. In systems where there is appreciable noble gas adsorption occurring, the timing and magnitude of radioactive noble gas signatures may be altered as observed by the International Monitoring System or during a potential On-Site Inspection.

Sandia National Laboratories is a multimission laboratory managed and operated by National Technology & Engineering Solutions of Sandia, LLC, a wholly owned subsidiary of Honeywell International Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525.

How to cite: Paul, M., Xu, G., Powell, M., Hearne, G., and Greathouse, J.: Noble Gas Adsorption onto Zeolitic Materials in Atmospheric Conditions, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10471, https://doi.org/10.5194/egusphere-egu23-10471, 2023.