Acoustic Wave Generation and Propagation from the Source Physics Experiments Investigated by Full 3D Finite-Difference Simulation

Session: Explosion Seismology Advances
Type: Oral
Date: 4/29/2020
Time: 11:15 AM
Room: 240
Description: 

The Source Physics Experiments (SPE), a series of underground chemical explosions conducted at the Nevada National Security Site, have provided a unique dataset to understand acoustic wave generation for underground explosions. Direct measurements of epicentral ground motions and local acoustic overpressure recordings showed that the acoustic waves were a direct response to the ground motions induced by buried explosions. As the extent of the epicentral area was comparable with or greater than the observed acoustic wavelengths, a simple point source approximation may not be valid to represent source mechanisms of the ground motion induced acoustic waves. The Rayleigh integral method has often been used to model acoustic wave generation by non-point sources. However, this method assumes a homogeneous medium and planar surface for wave propagation and hence, may not be applicable for heterogeneous atmospheres and non-planar topography in the source region. In this study, we investigate the use of a full 3-D finite-difference method to simulate acoustic wave generation and propagation by a non-compact source. Vertical ground motions over the finite extent of epicentral area are represented by distributed point sources on non-planar surfaces and acoustic wave propagation is simulated in realistic atmospheres with temperature, pressure and wind profiles. This method allows for predicting how the non-spherical acoustic wavefield near the source propagates to local and regional distances in the atmosphere. We explore this method and compare it with the ground truth data of the SPE, the point-source approximation and results from the Rayleigh integral.

Presenting Author: Keehoon Kim

Authors