Abstract
Two-dimensional P-SV-wavefields in laterally heterogeneous multi-layered media are calculated by using the hybrid combination of the boundary element method (BEM) and the thin-layer finite element method (TLFEM). The BEM can be combined with the TLFEM by matching the boundary conditions on vertical boundaries. Expansion of wavefield into summation of normal modes is used to match the boundary conditions. This method is suitable to calculate propagation of surface waves in laterally heterogeneous multi-layered media. It is easy to treat incident surface waves from distant sources, which is difficult to calculate by other boundary methods. Since this method does not require the assumption of periodic structure, it can be applicable to nonperiodical problems. Wavefields in a multi-layered slope structure are investigated. When a point source is in a thicker layer side, the amplitude of scattered waves is large and backscattered Rayleigh waves exist. When a point source is in a thinner layer side, Rayleigh waves whose dispersion corresponds to that for an averaged structure of both sides mainly propagate in the forward direction.
