Scattering of waves by a sedimentary basin with a corrugated interface

Antiplane strain and plane strain models for scattering of harmonic waves by a sedimentary basin with corrugated interface is investigated using an indirect boundary integral equation method. The corrugated interface is generated by adding to a smooth semielliptical shape a sinusoidal variation of prescribed amplitude and period or a random perturbation. Surface response is simulated for incident plane harmonic SH, P, SV, and Rayleigh waves for different frequencies, depth of the reference basin, amplitude, and period of corrugation. The results show that the presence of the corrugation may result in a significant reduction of peak surface ground motion atop the basin when compared with the corresponding smooth basin response. This reduction depends on polarization and frequency of the incident wave, the fundamental shape of the basin, and the nature of the corrugation. Especially pronounced reduction of the corrugated basin response is observed for incident SV waves. In addition, it is shown that the presence of the corrugation will affect the fundamental frequency of the basin as well when compared with the corresponding smooth basin case. Therefore, the results presented clearly demonstrate that neglecting the interface irregularities in modeling the basin response may result in a significant overestimate of the surface ground motion.