Seismic wave motion modeling with layered 3D random heterogeneous media

Abstract

A generalized earthquake-wave-motion model is established in this study, which considers 3D random heterogeneous media, together with existing models for sources and realistic geological profiles for sedimentary basins and irregular topography. The model can be used not only to examine the influences of random heterogeneous media, but also to explore the multiple interactions of source, site (irregularity and/or heterogeneity), and wave interference on spatial variations of ground motion. Specifically, the earth is modeled as a layered half-space with 3D weak-random heterogeneity media. Seismic waves are generated by a shear-dislocation source buried in one of the layers and then propagated through the modeled earth medium. A first-order perturbation approach together with wave propagation theory is used to solve the problem at hand for wave motion response, which is found as the superposition of the mean and scattered wave responses. The mean wave response is obtained as a wave-motion solution for a layered half-space without heterogeneity subjected to a buried seismic dislocation source. The scattered wave field is obtained as a wave-motion solution for the same layered half-space without heterogeneity subjected to virtual distributed body forces that mathematically replace the heterogeneity. The explicit expressions for the responses in both mean and scattered wave fields are derived in this study. A computational procedure for the wave-motion responses is also presented in detail.