The Source Physics Experiment on Seismic Waves Generated by Explosions: Results and Future Plans
Description:
The NNSA DNN R&D sponsored Source Physics Experiment (SPE) is a large, multi-institutional (LANL, LLNL, SNL, NNSS and UNR) effort to improve our understanding of how explosions generate seismic waves, particularly shear waves, to improve nuclear monitoring capabilities. The SPE includes a series of chemical explosions in southern Nevada in three Phases, each in a different borehole in contrasting geologies: SPE Phase I (2010-2016) was a saturated granite site; the Phase II (2016-2020) in Dry Alluvium Geology (DAG), and the current Phase III – Rock Valley Direct Comparison (RV/DC) is expected to be in dolomite. For each Phase the explosions vary in size and depth and are recorded on a common network, allowing ratios between events to be formed, canceling path and site effects and illuminating near source effects.
Near-field chemical SPE and historic nuclear data show high-frequency tangential motion is 20-30% of radial amplitudes, although the mechanisms that cause this vary with emplacement media. Within a few kilometers, far-field seismic amplitudes at 1-10 Hz are comparable across the 3 components, and the buried and surface explosions have comparable P/S amplitude ratios - both effects require rapid scattering and conversion to explain. The spectral ratios formed between small explosions used as Green’s functions and larger explosions are not well matched by existing explosion models, and the dry alluvium geology produces smaller amplitudes and appears deficient in high-frequency energy relative to explosions in granite. This shows the importance of material effects on explosive wave generation. We are examining factors such as absolute depth, scale depth, and material effects on shear wave generation, P/S and low/high frequency amplitude discrimination performance, and correlation behavior. These results are being used to develop a new explosion spectral model. For the current RV/DC Phase we plan to drill a corehole into a fault producing shallow seismicity to get physical samples and measurements in preparation for a future direct comparison of a shallow earthquake with a chemical explosion.
Session: Advancements in Forensic Seismology and Explosion Monitoring [Poster]
Type: Poster
Date: 4/17/2025
Presentation Time: 08:00 AM (local time)
Presenting Author: William
Student Presenter: No
Invited Presentation:
Poster Number: 97
Authors
William Walter Presenting Author Corresponding Author walter5@llnl.gov Lawrence Livermore National Laboratory |
Catherine Snelson snelsonc@lanl.gov Los Alamos National Laboratory |
Robert Abbott reabbot@sandia.gov Sandia National Laboratories |
Ian Whittaker whittaic@nv.doe.gov Nevada National Security Site |
Moira Pyle pyle4@llnl.gov Lawrence Livermore National Laboratory |
Miles Bodmer mabodme@sandia.gov Sandia National Laboratories |
Jesse Pine pineja@nv.doe.gov Nevada National Security Site |
Ethan Alger alger5@llnl.gov Lawrence Livermore National Laboratory |
Chris Carr cgcarr@lanl.gov Los Alamos National Laboratory |
Jose Falliner jlfalli@sandia.gov Sandia National Laboratories, Albuquerque, New Mexico, United States |
Colin N Pennington pennington6@llnl.gov Lawrence Livermore National Laboratory, Livermore, California, United States |
Jesse Bonner bonner21@llnl.gov Lawrence Livermore National Laboratory, Livermore, California, United States |
The Source Physics Experiment on Seismic Waves Generated by Explosions: Results and Future Plans
Category
Advancements in Forensic Seismology and Explosion Monitoring