Seismic Wavefields in Multi-Layered Media Calculated by Hybrid Combination of Boundary Element Method and Thin Layer Finite Element Method. The Case of Two-Dimensional SH-Wavefields.

Abstract

Two-dimensional SH-wavefields in laterally heterogeneous multi-layered media are calculated by using a hybrid method in which the boundary element method (BEM) is combined with the thin layer finite element method (TLFEM) by matching the boundary conditions on vertical boundaries. The traction operators defined on vertical boundaries are used to match the boundary conditions. The traction operators can be approximately calculated from eigenvalues and eigenfunctions for the multi-layered media, which are obtained by using the TLFEM. This method is efficient to calculate scattering of surface waves in laterally heterogeneous multi-layered media. Scattering of Love waves in multi-layered slope structure is investigated. For the case in which a source is in the shallower side, Love waves mainly propagate in the forward direction. The dispersion of Love waves shows an averaged structure of both sides. For the case in which a source is in the deeper side, the amplitude of scattered waves is large, and scattered body waves and back-scattered Love waves exist.