Author(s)

L. Godinho, A. Tadeu & F. J. Branco

Abstract

The propagation of elastic waves in layered half-space media containing a homogeneous basin can be simulated using different approaches. The present work proposes a methodology based on the Method of Fundamental Solutions (MFS) that makes use of the fundamental solution for a 2.5D elastic layered halfspace. The basin is modelled as an elastic material, whose properties are different from those of the host media. The proposed model is formulated in the frequency domain, and time responses are obtained by inverse Fourier transformation. Complex frequencies are used to avoid aliasing phenomena. The method is applied to study the case of a half-space with a semi-circular alluvial basin, illuminated by a point load, for which time signals are computed. Keywords: MFS, seismic waves, half-space, basin. 1 Introduction It is well known that site effects influence the nature of strong ground motion, causing, in specific situations, marked amplification phenomena (see Sanchez- Sesma [1]). Among other factors, surface topography is known to produce these so-called site effects, and there is significant evidence of the ground motion amplification it generates. Different approaches have been used to simulate the propagation of seismic waves in the presence of specific topographical deformations. Pedersen et al [2] used an indirect Boundary Element Method (BEM) formulation to calculate the three-dimensional seismic response of twodimensional topographies, under the influence of plane waves, using Green’s functions for an infinite space. Reinoso et al [3] used a BEM formulation to compute the 3D reflections by valleys and irregular topographic deformations.

Keywords

MFS, seismic waves, half-space, basin