Insights From the Source Physics Experiment on Seismic Waves Generated by Explosions
Session: Explosion Seismology Applications and Advances II
Type: Oral
Date: 4/19/2021
Presentation Time: 02:15 PM Pacific
Description:
The NNSA DNN R&D sponsored Source Physics Experiment (SPE) is a large, multi-institutional (LANL, LLNL, SNL, MSTS 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 two different boreholes in contrasting geologies. The explosions vary in size and depth and for each location they are recorded on a common network, allowing ratios between events to be formed, canceling path and site effects and illuminating near source effects. Surface explosions were also conducted above the boreholes: at the SPE Phase I granite site in 2016, and under DTRA sponsorship at the SPE Phase II dry alluvium geology (DAG) site during the Large Surface Explosive Coupling Experiment (LSECE) in 2020.
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 requiring 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, which must be taken into account for monitoring analyses. 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.
Presenting Author: William R. Walter
Student Presenter: No
Authors
William Walter Presenting Author Corresponding Author walter5@llnl.gov Lawrence Livermore National Laboratory |
Sean Ford sean@llnl.gov Lawrence Livermore National Laboratory |
Arben Pitarka pitarka1@llnl.gov Lawrence Livermore National Laboratory |
Moira Pyle pyle4@llnl.gov Lawrence Livermore National Laboratory |
Michael Pasyanos pasyanos1@llnl.gov Lawrence Livermore National Laboratory |
Gene Ichinose Ichinose1@llnl.gov Lawrence Livermore National Laboratory |
Andrea Chiang chiang4@llnl.gov Lawrence Livermore National Laboratory |
Robert Mellors rmellors@ucsd.edu University of California, San Diego |
Souheil Ezzedine ezzedine1@llnl.gov Lawrence Livermore National Laboratory |
Oleg Y Vorobiev vorobiev1@llnl.gov Lawrence Livermore National Laboratory, Livermore, California, United States |
Douglas Dodge dodge1@llnl.gov Lawrence Livemore National Laboratory, Livermore, California, United States |
Eric Matzel matzel1@llnl.gov Lawrence Livermore National Laboratory, Livermore, California, United States |
Jeff Wagoner wagoner1@llnl.gov Lawrence Livermore National Laboratory, Livermore, California, United States |
Insights From the Source Physics Experiment on Seismic Waves Generated by Explosions
Category
Explosion Seismology Applications and Advances