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Simulations of Local Wave Propagation Effects on the Performance of P/s Source Discriminant

Description: 

Analysis of seismic records of local earthquakes and a series of underground chemical explosions conducted during the Source Physics Experiment (SPE) at the Nevada National Security Site have shown that at local distances (<200 km) the effectiveness of the single-station P/S ratio source discriminant is reduced, especially when seismic recordings from a sparse network of stations is used.

We used high performance computing to simulate high-frequency (0-10Hz) waveforms of the recorded SPE-5 underground chemical explosion and one local earthquake for a network of seismic stations in the Yucca Flat, and a series of simulations of collocated isotropic and double-couple explosion sources in the Rock valley, to investigate the effects of source radiation and wave scattering effects on the simulated waveforms and P/S source discriminant at local distances. The wave propagation scattering was simulated by using the Yucca Flat Geological Framework Model (GFM) with correlated small-scale stochastic perturbations.

The inclusion of correlated depth-dependent stochastic velocity perturbations in the GFM, improved the quality of simulated source radiation and local waveforms, which resulted in better reproduction of the observed spatial variations of the P/S discriminant. We found that the shallow wave scattering deforms the radiation pattern and amplitude of source generated P and S waves, thus reducing the efficiency of the P/S discriminant. Our simulations suggest that a good azimuthal stations coverage and the network averaging can improve the overall performance of the P/S discriminant at local distances.

Session: Advancements in Forensic Seismology and Explosion Monitoring - II

Type: Oral

Date: 5/2/2024

Presentation Time: 11:30 AM (local time)

Presenting Author: Arben

Student Presenter: No

Invited Presentation: 

Authors