3-D wave propagation using finite differences

A finite difference approximation of the elastic wave equation has been implemented on the massively parallel Connection Machine (CM-2). Realistic three dimensional Earth models can be created by a joint surface modeling package (GOCAD). Anisotropic stiffnesses may be attributed to each homogeneous domain using Hudson's theory for cracks or the group theoretical formulations by Schoenberg and Muir for fractured and multiply layered media. We are studying the properties of anisotropic waves in three dimensions. We also attempt to model seismic trapped modes in low velocity layers, a situation which is likely to exist in coal seams or fault zones.