On Seismic Response of Attenuated Orthotropic Gaussian-Shaped Sedimentary Basin

Saeed Mojtabazadeh-Hasanlouei
Mehdi Panji
Mohsen Kamalian

The surface motion of an orthotropic Gaussian-shaped sedimentary basin embedded in a linear elastic half-space was successfully obtained under transient SH-wave propagation. In the use of the time-domain boundary element approach, a simple model was developed only by discretizing the interface. To achieve better convergence of the response, an attenuation rule was implemented with the assistance of the reduction exponential function applied in the boundary integral equations. After a brief overview of the method, the heterogonous sub-structured basin model was created and decomposed into two parts to satisfy the modified continuity conditions based on the normal direction at the interface node position. The developed computer code was tested by solving a validation example. Finally, to illustrate the basin surface response in the time/frequency-domain, a general sensitivity analysis was performed by considering the parameters of frequency, isotropy-factor, wave angle, seismograms, and amplification patterns. The results showed that the effect of orthotropic anisotropy was very efficient on the ground response and different seismic patterns on the surface of sedimentary basins were extracted by changes in the quantity of this parameter.