Description
E-poster session with display of each e-poster on an assigned touchscreen
The isotopic ratio of radioxenon is crucial for distinguishing between civilian sources and nuclear explosions. This study focuses on using the Xe-135/Xe-133 ratio to precisely determine the origin time of detected radioxenon. Due to the shorter half-life of Xe-135 compared to Xe-133, this ratio decreases over time, serving as a reliable indicator for estimating the sample's age.
At the...
Bolides, or exceptionally bright meteors resulting from the atmospheric entry of asteroids or meteoroids typically over 10 cm in diameter, provide significant infrasound sources for global monitoring efforts. Originating from cometary or asteroidal fragments, these objects enter Earth's atmosphere at hypervelocity, generating shockwaves that decay into low-frequency (<20 Hz) sound or...
Localization and characterization of nuclear detonations can be accomplished using various observation techniques, including seismic and infrasound data. In both cases, accurate knowledge of the propagation medium - specifically, Earth's subsurface and atmospheric properties - is essential for reliable inversion results. This study introduces a joint inference framework designed to localize...
Characterizing seismic sources is critical to accurately constraining important seismic source features of interest. Many factors affect seismic far-field waveforms (FFWFs) used for source characterization, including physical characteristics near the source, such as emplacement or ground material properties. How near-source characteristics and the methods with which we estimate source features...
Urban environments present unique challenges for seismic event monitoring and discrimination. Persistent anthropogenic noise can reduce the signal-to-noise ratios of seismic events and impulsive man-made events can falsely trigger detection algorithms. One approach to improving our monitoring algorithms—to accommodate diverse detection environments—is to incorporate more dynamic anthropogenic...
Electromagnetic signatures from the Low Yield Nuclear Monitoring PE1 Shot A conducted in October 2023 at the Nevada Nuclear Security Site have been analyzed. The data show signals from the hot, expanding plasma in the Earth's natural magnetic field and from seismo-electric mechanisms. However, the polarization signatures of the prompt signal do not match predictions from a simple "magnetic...
Understanding the propagation of long-range acoustic waves is a cornerstone of infrasound research, yet solving the wave equation remains a computationally intensive challenge. This complexity is further exacerbated by the need for recalculations whenever the sound speed structure or source characteristics change. In this study, we present an innovative application of the Fourier Neural...
Given the existing radioxenon and radioaerosol backgrounds encountered by the IMS, detections of multiple isotopes are useful for screening purposes. We examined this issue by using six UNE release scenarios, including fractionated ones based on the literature, and subsequent atmospheric transport to IMS stations. The study identifies those radioisotopes (radioxenon and particulate) that are...
The Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) has established automated processes for routine event analysis, resulting in standard products. However, in cases where unusual events or suspicious measurements occur (e.g. elevated radionuclide levels or seismic activity suggesting a nuclear test), further investigation might be necessary to ensure accurate characterization and...
Various nuclear test monitoring techniques require numerous waveforms and expect good spatial coverage of seismic source. The examples, inter alia, are master-event based location and event discrimination, needing data augmentation due to class imbalance and synthetic seismogram simulation can make a job. Generative Networks (GN) are a novel way of producing realistic, high-quality synthetic...
Recently, the detection of two small seismic events that have occurred close to sites where North Korea carried out underground nuclear weapons tests was reported in the literature. A seismic event, considered to be a small earthquake of magnitude 1.5, occurred on 12 May 2010 close to the site of the 25 May 2009 underground nuclear test (UNT) in North Korea. Another seismic event of magnitude...
Rocket launches and reentries are powerful atmospheric noise sources detectable at infrasound arrays in thousands of kilometers distance. Recorded signatures originate from the ignition, launch, supersonic movement, stage separation and reentry of rockets within the first about 100 kilometers of altitude of the atmosphere. We use IMS infrasound data to localize and characterize these events...
The classification of infrasound signals has important application value in the fields of nuclear test monitoring, earthquake and other natural disaster warning. However, traditional infrasound signals classification methods are difficult to effectively extract the significant features that quantify event differences. To address this issue, this paper proposes an end-to-end infrasound signal...
Characterisation of seismic sources, including earthquakes and explosions, is of interest to the nuclear-test-ban verification community. At local to near-regional distances (≤300km) signals from quarrying, mining and controlled explosions are commonly observed in addition to earthquake seismicity. We investigate the ratio of P- to S- wave amplitudes as a seismic source discriminant for...
The DPRK test-site is within regional distances from the Tohoku earthquake fault. No DPRK explosion was conducted during the time when the highest amplitude Tohoku seismic signals travelled over the globe. The conduction of an underground nuclear test near and just after one of the largest earthquakes ever is a well-known evasion scenario. Seismic data from the IMS stations is available for...
The re-entry of NASA’s OSIRIS-REx Sample Return Capsule (SRC) into Earth’s atmosphere in 2023 provided a unique opportunity to detect and analyze infrasound generated by a controlled atmospheric entry. As the SRC traversed denser atmospheric layers at hypervelocity, it produced shock waves that decayed into acoustic signals. The strategic placement of ground-based and airborne sensors along...
A transfer learning approach was adopted, using a VGG16 neural network model to classify earthquakes from non-earthquake events in North-East China, close to the North Korean test site. Magnitudes below 4 are considered for classification of tectonic events (earthquakes) from explosions. Because of the scarcity of observed explosion data, synthetic seismograms were generated using SW4 to...
On 28 May 1998, Pakistan detonated its first nuclear explosion. The teleseismic P-waves from this seismic disturbance are complex compared to those typically observed from underground explosions. We observe a spatial correlation between waveform simplicity and take-off angle; with the most simple seismograms being recorded at small take-off angles at the source (${\Delta}$ < 15$^\circ$) and at...
The global verification system under the Comprehensive Nuclear-Test-Ban Treaty (CTBT) is designed to detect all nuclear explosions on Earth, with seismic monitoring relying on the International Monitoring System (IMS) to identify explosion signals. This study applies Moment Tensor (MT) inversion analysis to assist States Parties through expert technical analysis (ETA) of IMS and additional...
The three-dimensional (3D) spatial analysis of radioxenon isotopic activity ratios is a powerful approach for the determination of the time of a nuclear event. In contrast to the 2D planar analysis, this method requires at least a triple detection from the same sample among the four CTBT-relevant radioxenon isotopes, which are 131mXe, 133mXe, 133Xe, and 135Xe. One method of the 3D spatial...
Seismic moment tensors are a fundamental tool used to characterize events of interest to the nonproliferation community. Understanding and quantifying the uncertainty in moment tensor solutions are key to that characterization task. There are many sources of uncertainty confounding the accurate recovery of moment tensors, including imperfect knowledge of Earth structure between the source...
In the absence of active nuclear explosive testing, large chemical explosions provide an opportunity to test our ability to monitor for explosions over broad regions. Accidental explosions, most of them occurring near the surface, provide a good test for monitoring at low yield, where the seismic signals are further reduced due to the weaker coupling at shallow depths. Effective explosion...
In 2012, the National Research Council concluded that earthquake signals cannot effectively mask those produced by explosions. We test that conclusion with multi-channel correlation detectors (correlators) that use records of ground motion (templates) sourced by explosions to detect smaller signals from similar, collocated sources. Our test applies these detectors against thousands of signals...
The National Preparedness Exercises (NPE) are held regularly to practise analysis and test procedures within the NDCs and in exchange with the IDC. The German NDC has been organising the NPE series since 2007. The NPE 2024 was announced by the fictitious NDC Andlantis in the NDC Forum. Key elements of the information released included:
- National seismic data in a rather unusual format...
During the SnT2023, Mulwa and Dindi (2023) presented case examples of systematic seismic events discrimination methods at KE-NDC. The results were subsequently published in Pure and Applied geophysics journal (see Mulwa, 2024 in PAGEOPH, https://doi.org/10.1007/s00024-024-03458-4). The NPE2024 entailed a request by the State of “Andlantis” for Expert Technical Analysis (ETA) of potentially...
The ability to generate waveforms up to 10 Hz through modeling provides a necessary tool to understand the full extent to which a signal may be characterized. Using HPC resources we demonstrate the current capability of SW4 to generate waveforms to compare measurements. The observed features help us understand the differences in source properties and our ability to resolve them with the...
A new method to invert regional seismograms had recently been presented to extract the yield and depth of explosions which are accompanied by contributions from both double couple (DC) and a strong compensated linear vector dipole (CLVD) source (presented in this conference by Saikia). In this paper, we are applying this approach to investigate the reliability of the yield and depth of the...
