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Joint Inversion of Regional Waveform, First-Motion Polarity, and Synthetic Aperture Radar Surface Displacement for the Fourth and Sixth North Korean Declared Nuclear Explosions
Here, this study analyzed the Democratic People’s Republic of Korea’s (DPRK) fourth (DPRK4, 6 January 2016 M w 4.49) and sixth (DPRK6, 7 September 2017 M w 5.2) declared nuclear tests, employing a joint seismic and Interferometric Synthetic Aperture Radar (InSAR) inversion to improve understanding of these events and enhance moment tensor (MT) inversion capabilities. The recent efforts have focused on employing seismic waveform and InSAR geodetic deformation data separately to analyze these and the previous nuclear tests (e.g., Chiang et al., 2018; Myers et al., 2018; Wang et al., 2018). Building upon our previous work (Chi-Durán et al., 2021), we performed a joint regional waveform, first-motion (FM) polarity, and surface displacement inversion, which demonstrated improved source-type discrimination, a revised MT solution with reduced scalar moment uncertainty, and an independently constrained location. In this article, we build on the previous results for DPRK6 by including an analysis using a four-layered velocity model with free-surface topography to compute the near-source static deformation Green’s functions. The model consists of a 50 m basalt layer (V P = 2.07 km/s, V S = 1.2 km/s), a 250 m stratified volcanic deposit layer (V P = 1.73 km/s, V S = 1.0 km/s), a 700 m weathered granodiorite layer (V P = 2.5 km/s, V S = 1.3 km/s), and a granodiorite half-space (V P = 5.35 km/s, V S = 3.09 km/s). The half-space shares the velocity of the regional MDJ2 velocity model (Ford et al., 2010), which has proven effective for waveform inversion in the region. This model considers the range of reported values for various lithologies and weathering effects. Our findings show that using the layered velocity model enhances the recovery of source location and depth for both the explosions by improving fits and reducing uncertainties. The joint inversion also improves source-type discrimination and better constrains the scalar seismic moment necessary for downstream yield estimation.
Open Data for Nuclear Explosion Monitoring (NEM) [Slides]
The data sources tend to have the highest quality data and metadata, particularly for more recent data sets. Early data from sources such as IRIS tend to have some metadata issues.
Nuclear Explosion Monitoring in the Changing Arctic
As the Arctic warms and loses its perennial ice cover, it attracts new attention as a locus for resource extraction, commerce, communication, and defense. The region previously had a relatively low priority in global geopolitics due to operational challenges but is quickly attracting interest for economic growth, competition, and potential conflict. Future years and decades will see a transformation of the Arctic’s place in global geopolitics. In this context, monitoring both human and natural activity in the Arctic is increasingly critical.
Nuclear explosion monitoring network design considerations
Design of an efficient monitoring network requires information on the type and size of releases to be detected, the accuracy and reliability of the measuring equipment, and the desired network performance. This work provides a scientific basis for optimizing or minimizing networks of 133 Xe samplers to achieve a desired performance level for different levels of release. The approach of this work varies the density of sampling locations to find optimal location subsets, and to explore the properties of variations of those subsets – how crucial is a specific subset; are substitutions problematic? The choice of possible station locations is arbitrary but constrained to some extent by the location of islands, land masses, difficult topography (mountains, etc.) and the places where infrastructure exists to run and support a sampler. Performance is evaluated using hypothetical releases and atmospheric transport models that cover an entire year.
Cavity-melt partitioning of refractory radionuclides and implications for detecting underground nuclear explosions
Not Available
Comparison Between Historic Nuclear Explosion Yield Formulas
Not Available
Applying Compression Distance Metrics to Seismic Data in Support of Global Nuclear Explosion Monitoring.
Abstract not provided.
A multi-Physics Experiment for Low-Yield Nuclear Explosion Monitoring
A series of multi-physics experiments, referred to as Physics Experiment 1 (PE1) is underway at the United States’ Nevada National Security Site (NNSS). The PE1 series includes detonations of three underground chemical explosions in P-tunnel, with fully coupled (PE1 A), partially decoupled (PE1 D L ), and fully decoupled (PE1 B) emplacements. Canisters with gas tracers are imbedded in the explosives, and the tracers are released when the canister is destroyed by the detonation. A dedicated electromagnetic (EM) experiment (EMX) generates well-characterized EM signals at an underground location near the chemical explosive experiments. A series of atmospheric experiments (METEX, REACT, and METREX) release smoke and radioactive tracers around Aqueduct Mesa to test gas transport in complex topography. Each of the chemical explosive experiments includes a network of sensors to record seismic, acoustic, and electromagnetic waves, measurement of atmospheric conditions, and air sample collection for measurement of tracer concentration. EMX records EM signals underground and on the surface of Aqueduct Mesa. METEX, REACT, and METREX include measurement of atmospheric condition, as well as tracking smoke releases. REACT and METREX add low-level radioactive gas tracers to the atmospheric releases.
OBSERVATORY ACOUSTIC-GRAVITY WAVE PROPAGATION FROM NUCLEAR EXPLOSIONS IN THE EARTH'S ATMOSPHERE
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Effect of shock on fission track dating of apatite and sphene crystals from the Hardhat and Sedan undergound nuclear explosions
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Nuclear Deterrence and Vigilance: The role of Space-Based Nuclear Explosions Monitoring
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Stable Element Doping of Sol-gel Toward Simulating Environmental Matrix in Surrogate Explosive Nuclear Debris
Training nuclear forensic analysis personnel in post-detonation scenarios is of critical importance to nuclear threat response capabilities. Thus, realistic nuclear debris simulants which resemble the size, color, elemental composition, and radionuclide content of actual nuclear fallout from a recent detonation would be valuable for training nuclear first responders in realistic scenarios. As nuclear fallout types vary significantly in each of these parameters based on detonation environment (rural, urban, maritime etc.) and collection location, the ability to tailor each of these parameters accurately in simulated debris would be of immense benefit to the post-detonation analysis community for training both in-field collections and triage and the validation of laboratory level nuclear forensic techniques. Sol-gel synthesis techniques can provide the tunability of size, shape and composition required for producing surrogate nuclear debris of a wide variety. The sol-gel process consists of forming a metal oxide material, often silica, through polymerization of a metal-alkoxy precursor. In this work, we characterize the ability to load the sol-gel particles with secondary elemental components such as iron, aluminum, and calcium toward approximating the elemental composition of debris from various detonation environments and demonstrate the ability to produce particles with controllable size, shape, and color. We also demonstrate quantitative radionuclide encapsulation toward reproducing the radionuclide content of actual fallout from a recent detonation. Finally, we then employ these techniques in producing simulated aerodynamic debris samples with realistic elemental matrix composition and radionuclide content simulating a recent uranium-fueled detonation taking place in a rural desert environment and compare it to historic fallout from the Nevada Nuclear Security Site.
Stable Element Doping of Sol-gel Toward Simulating Environmental Matrix in Surrogate Explosive Nuclear Debris
Training nuclear forensic analysis personnel in post-detonation scenarios is of critical importance to nuclear threat response capabilities. Thus, realistic nuclear debris simulants which resemble the size, color, elemental composition, and radionuclide content of actual nuclear fallout from a recent detonation would be valuable for training nuclear first responders in realistic scenarios. As nuclear fallout types vary significantly in each of these parameters based on detonation environment (rural, urban, maritime etc.) and collection location, the ability to tailor each of these parameters accurately in simulated debris would be of immense benefit to the post-detonation analysis community for training both in-field collections and triage and the validation of laboratory level nuclear forensic techniques. Sol-gel synthesis techniques can provide the tunability of size, shape and composition required for producing surrogate nuclear debris of a wide variety. The sol-gel process consists of forming a metal oxide material, often silica, through polymerization of a metal-alkoxy precursor. In this work, we characterize the ability to load the sol-gel particles with secondary elemental components such as iron, aluminum, and calcium toward approximating the elemental composition of debris from various detonation environments and demonstrate the ability to produce particles with controllable size, shape, and color. We also demonstrate quantitative radionuclide encapsulation toward reproducing the radionuclide content of actual fallout from a recent detonation. Finally, we then employ these techniques in producing simulated aerodynamic debris samples with realistic elemental matrix composition and radionuclide content simulating a recent uranium-fueled detonation taking place in a rural desert environment and compare it to historic fallout from the Nevada Nuclear Security Site.
Comparison of Nuclear and Explosive Destruct Concepts for Nuclear Rocket Engines
Nuclear and explosive destruct concepts for nuclear rocket engines
Measurement of Argon-37 Background Concentrations in the Atmosphere
Radioisotopes of noble gases, primarily xenon and argon, are important indicators of underground nuclear explosions. The Comprehensive Nuclear-Test-Ban Treaty (CTBT) includes monitoring capabilities to identify potential nuclear explosions conducted in violation of the CTBT. This monitoring currently focuses on measurement of the xenon isotopes 133 Xe, 135 Xe, 131 mXe and 133 mXe. However, it is predicted that within 100 days of an underground nuclear explosion (UNE) 37 Ar would be released to the atmosphere at higher concentrations than xenon isotopes (Haas et al. 2010). Therefore, inclusion of 37 Ar measurement capabilities at atmospheric International Monitoring System (IMS) stations could improve the capability to detect a nuclear explosion. At an IMS station, it could be difficult to determine what constitutes an elevated concentration as a result of an UNE without first understanding the expected range of background concentrations. This work describes our analysis of atmospheric samples for 37 Ar to evaluate the range of background concentrations. The range of 37 Ar concentrations measured in atmospheric air samples was relatively narrow ranging between less than 1 mBq/m 3 to greater than 2 mBq/m 3 . The average atmospheric concentration of all samples was 0.98 mBq/m 3 , with a standard deviation of 0.5 mBq/m 3 . This is consistent with previous published results. The results presented here demonstrate the capability to detect background concentrations of 37 Ar in atmospheric air.
Comparison of near-background concentrations of Argon-37 and Xenon-133 in the Atmosphere
Radioisotopes of noble gases xenon and argon can be important indicators of underground nuclear explosions. The Comprehensive Nuclear-Test-Ban Treaty (CTBT) includes monitoring capabilities to identify potential nuclear explosions conducted in violation of the CTBT. This monitoring currently focuses on measurement of the xenon isotopes 133Xe, 135Xe, 131mXe and 133mXe. However, it is predicted that within 100 days of an underground nuclear explosion (UNE) 37Ar would be released to the atmosphere at higher concentrations than xenon isotopes (Haas et al. 2010) and with a higher signal to background ratio, depending on the radioxenon background levels. Therefore, inclusion of 37Ar measurement capabilities at atmospheric International Monitoring System (IMS) stations may represent an improvement in the capability to detect a nuclear explosion. At an IMS station, it could be difficult to determine what constitutes an elevated concentration as a result of an UNE without first understanding the expected range of background concentrations. This work describes our analysis of atmospheric samples for 37Ar to evaluate the range of background concentrations. Samples were collected at multiple locations, with approximately half coming from a sampler co-located with an IMS xenon monitoring station (RN75). The range of 37Ar concentrations measured in atmospheric air samples was relatively narrow; for samples considered detectable, the minimum and maximum measured concentrations were 0.56 and 2.3 mBq/m3, respectively. Comparison of 37Ar and 133Xe concentrations measured at the IMS station indicated some correlation between the measured concentrations. The results presented here demonstrate the capability to detect background concentrations of 37Ar in atmospheric air and provide a basis for potential implementation of 37Ar monitoring at IMS stations.