Amplification of elastic waves due to a point source in the presence of complex surface topography

This paper first presents the amplification or de-amplification in the thre e-dimensional wave scattering generated by the half-space when subjected to a dilatational point load placed at some point in the medium, when the fre e surface is changed to simulate a two-dimensional ridge or a valley deform ation. This model is then extended to include the presence of a long, circu lar, buried cavity. The solution is formulated using the boundary elements method for a wide range of frequencies and spatially harmonic line loads, w hich are subsequently used to obtain time series by means of (fast) inverse Fourier transforms into space-time. Our simulation results indicate larger wave amplification and de-amplificat ion in the time and frequency domains when the topographic surface includes a smooth ridge and canyon deformations. The presence of a buried inclusion further complicates the wave field displacement pattern, including additio nal reflections. (C) 2001 Elsevier Science Ltd. All rights reserved.