WAVE SCATTERING BY A CANYON OF ARBITRARY SHAPE IN A LAYERED HALF-SPACE.

To calculate the generalized scattered motion in the region of a canyon of arbitrary shape in a horizontally layered half-space, the indirect-boundary-element method in the frequency domain is applied. Fictitious distributed source loads acting on the line which will form the surface of the canyon are used. The corresponding Green's functions, which are determined by a transformation to the wave-number domain, satisfy the conditions at the interfaces of the adjacent layers including those at the free surface. The discretization with boundary elements can thus be restricted to the line which will form the surface of the canyon. By formulating a weighted residual statement, the sum of the surface tractions composed of those of the free field and of the fictitious loads averaged over each boundary element are set equal to zero. Based on vast parametric studies addressing inclined body waves and surface waves for the out-of-plane and in-plane cases, the amplification patterns within and adjacent to the canyon are studied and conclusions are stated.