Pinpointing Seismic Events with Body Waves Scattered by Topography Near the Source Region
Technical Report,31 May 2017,30 Jun 2019
University of Rhode Island Narragansett United States
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This contract explores the power and limitation of a novel, seismic event location method based on waves scattered by surface topography. We validated this method, using seismic data from the 1993 Non-Proliferation Experiment, a chemical explosion with a precisely known location at the Nevada Test Sites, a region with moderate topography. We explored the effects of velocity heterogeneity, signal frequencies, time windows and other factors on the scattered waves and estimated locations. We applied this method to the Sept. 3rd 2017 DPRK nuclear test, using records from four seismic stations in China and South Korea. The solution is within 1 km of those of several other studies. We also studied the effects of 3D velocity models on full-wave moment tensor solutions of the DPRK nuclear tests. The moment tensor solutions show a dominant isotropic component, as expected from explosions, though there are also notable non-isotropic components. The event following the explosion contained mainly an implosive component, consistent with a tunnel collapse.