Coupling of FDM and FEM in seismic wave propagation

International audience; A specific approach is studied to couple two well-known numerical methods, a finite difference method (FDM) and a finite element method (FEM) for simulating regional seismic wave propagation to local site response. This coupling uses a technique of the “paraxial approximation” in order to input in the FEM the seismic wave generated in the FDM. The main advantage of this approach is to locally extract an area of interest where non-linear soil response or complex geometry is important from the regional wave propagation in a relatively simple medium. This result in taking advantage of both methods: the portability of the FDM and the flexibility of the FEM. This paper presents a theoretical framework of the paraxial approximation, through which the coupling is realized between the FDM and the FEM, and demonstrates some examples for the validation of the proposed coupling technique as well as its possible applications.