Key points are not available for this paper at this time.
We consider the three-dimensional elastic wave equation for an isotropic heterogeneous material subject to a stress-free boundary condition. Building on our recently developed theory for difference methods for second order hyperbolic systems H.-O. Kreiss, N. A. Petersson, J. Yström, SIAM J. Numer. Anal., 40 (2002), pp. 1940–1967, we develop an explicit, second order accurate technique which is stable for all ratios of longitudinal over transverse phase velocities. The spatial discretization is self-adjoint, and the stability is obtained through an energy estimate. Seismic events are often modeled using singular source terms, and we devise a technique to place sources independently of the grid while retaining second order accuracy away from the source. Several numerical examples are given.
Nilsson et al. (Mon,) studied this question.