SOIL AMPLIFICATION OF SURFACE WAVES

Abstract

A second order accurate in time and fourth order accurate in space (2, 4) P-SV wave staggered grid fmite-difference algorithm developed by Narayan and Kumar (2012) is used for the computation of responses of various considered models. This algorithm is efficient enough to incorporate the frequency dependent damping in time domain finite-difference simulation based on Rheology of_well known generalized Maxwell body. In order to verify that whether Rayleigh wave damping is affected by only S-wave damping or by damping of both the P-wave and S-wave, seismic responses of a homogeneous viscoelastic model were computed for different combination of damping. Simulated results revealed that Rayleigh wave damping depends on the both the P-wave and S-wave damping but more on the S-wave damping. In this dissertation the effect of impedance contrast across the basin edge, Rheology of sediment in basin and soil thickness on the complex mode transformation of Rayleigh wave and spectral amplification of basin-transduced Rayleigh waves (BTR-wave) is documented. Simulated results revealed a complex mode transformation of Rayleigh wave at basin edge and caused reflected Rayleigh waves and different modes of BTR-waves in the basin. An increase of spectral amplification of BTR-wave with increase of impedance contrast was obtained. An increase of wiggles in spectral amplification with increase of distance from basin-edge was inferred probability due to the dispersion effects. A decrease of spectral amplification as well as average spectral amplification was obtained with increase of damping and distance from the basin-edge. Larger amplification of horizontal component of BTR-wave was noticed when soil thickness was less than 100 m. Average spectral amplification for both components was almost similar when soil thickness was more than equal to 200 m.