Calculation of Surface Waves For A Thin Basin Structure Using A Direct Boundary Element Method With Normal Modes

An efficient method to synthesize surface waves in a thin sedimentary basin exhibiting lateral heterogeneities is proposed. This method is based on the direct boundary element method; that is, it represents the wavefield by integral equations along boundaries. the excitation and propagation of surface waves by lateral heterogeneities are incorporated into the numerical scheme by using propagation operators and superposition, where the Green's function is computed by the summation of normal modes when the horizontal distance between the source and receiver is large, which reduces computation costs. Using the properties of the surface‐wave part of Green's function, the number of elements needed for discretization can be reduced. This formulation can be effective for both the physical interpretation of certain observed phases and for numerical calculations. In this paper, only 2‐D SH problems are considered, and the extension to 2‐D P‐SV problems and 3‐D problems is discussed briefly.