Effects of geometry and rheological parameters of large basin on the SH-wave response of sub-basin in the basin-sub-basin models

Abstract

The effects of impedance and shape-ratio of large basin on the nature of occurrence of 2D resonance, spectral amplifications, sub-basin-induced Love (SBIL)-waves and sub-basin-transduced Love (SBTL)-waves and associated differential ground motion (DGM) across the sub-basin of the basin-sub-basin models are documented in this paper. The analysis of SH-wave responses of the considered small basin, large basin, and various basin-sub-basin models reveals that the presence of large basin does not change the occurrence of 2D resonance phenomenon in the sub-basin. But, the presence of large basin reduces the fundamental frequency ($$ {F}_{02D}^{SLB}\Big) $$ of sub-basin and increases the spectral amplifications and amplitude of the SBIL-wave in the sub-basin. The cause of reduction of $$ {F}_{02D}^{SLB} $$ of sub-basin is the decrease of the lowest fundamental mode of vibration of basin-sub-basin model in the vertical direction. A considerable effect of location of sub-basin, impedance, and shape-ratio of the large basin on the amplitudes of both the SBIL- and SBTL-waves is observed. The amplification of SBTL-wave in the sub-basin is due to the drop of impedance and the decrease of wavelength of SBTL-wave in the vertical direction. A decrease of DGM with an increase of span and decrease of shape-ratio of the large basin is obtained. The obtained largest DGM of the order of 1.85 × 10−3 near the edge of sub-basin for 1 cm/s particle velocity at basement level calls for further study on the complex basin and sub-basin interaction effects on the ground motion characteristics for earthquake engineering purposes.