Scattering of plane SH waves by a concentric semi-cylindrical discontinuity and canyon

The discontinuity of the medium and the irregularity of the ground significantly affect the propagation of seismic waves. However, the comprehensive effects of these two factors on seismic motion have not yet been fully investigated. To reveal the mechanism of dynamic interaction between the discontinuity and the irregular topography, this study provides a series of solution for the scattering of plane SH waves caused by a concentric semi-cylindrical discontinuity and canyon in an elastic half-space, using the displacement discontinuity model and the wave function expansion method. Based on the proposed series solution, a systematic analysis is conducted to investigate the influences of the stiffness of the discontinuity, the radius ratio between the discontinuity and the canyon, and the properties (e.g., frequency and angle) of the incident wave on the ground motion and underground motion. The results indicate that the stiffness of the discontinuity is a key factor determining the distribution of seismic motion. A high stiffness leads to a distribution similar to that of the canyon alone, while a low stiffness results in a much more complex distribution.