Seismic Wave Generation and Propagation from Complex 3D Explosion Sources.

摘要

We are investigating generation of complex seismic waves by explosions in media with realistic 3D heterogeneity, including topography and tectonic strain release. We have developed a 3D nonlinear finite element code CRAM3D designed for calculation of explosions in 3D heterogeneous media with well-tested material models and including gravity; and implemented interface codes using the representation theorem that propagate the numerical solution from the source region to regional and teleseismic distances. We simulated the nonproliferation experiment (NPE) including the effects of surface topography. We added the capability to calculate explosions with tectonic strain release. We specifically model the nuclear explosion Shoal. Shoal is in an area with northwest extension, which amplifies motion in that direction. Waveforms from the 3D calculation of Shoal are consistent with observed near field waveforms and surface wave radiation patterns. We also calculate far-field body waves and find that tectonic release has very little effect on far-field P-wave amplitudes, although it does generate SH waves not present in the calculation without tectonic release. This implies that while tectonic release may significantly affect Ms, the effect on mb will be small.