An analytical solution of scattering of semi-circular hill on cylindrical SH waves

摘要

Irregular topography can induce scattering and diffraction of incident seismic waves and cause topographic amplification effects. In this paper, a theoretical model for the scattering and diffraction of cylindrical SH waves caused by a semi-circular hill is established for the first time to reveal the influence of source characteristics on the topographic amplification effects. The analytical solution of the theoretical model is derived via the wave function expansion method and image theory, and its accuracy is verified by checking the given boundary conditions. Base on the presented solution, the influences of source location, incident wave frequency, and hill radius on amplitude amplification are systematically investigated. Comparison of amplitude amplification around the hill caused by cylindrical waves and plane waves indicates that the effect of source distance on topographic amplification effects is not negligible unless the source distance exceeds 15 times the hill radius. It suggests that much attention should be paid to the effects of source location on topographic amplification effects, especially when the source is near the topography.