Composite absorbing boundaries for the numerical simulation of seismic waves

Abstract

AbstractComposite absorbing boundary methods are developed for the numerical simulation of seismic waves. These methods combine low-angle absorbing boundary conditions, based on the characteristic analysis of one-dimensional wave equations, with either of two novel wave field modification approaches, namely the anisotropic filters and the one-way sponge filters. The anisotropic filter method adjusts the propagation direction of the waves, so that they reach the boundary at normal angles. The one-way sponge filter method endows the transition zone with a dissipation mechanism that selectively damps the incoming waves. These methods absorb not only the body waves but also the surface waves. A narrow transition zone adjacent to a computational boundary is introduced whose width is smaller than in the sponge filter approach. Numerical examples illustrate the effectiveness of these methods in absorbing the artificial reflections.