Estimation of S-Wave Velocity Structure Model by Joint Inversion of Site Amplification, Receiver Function and Phase Velocity of Rayleigh Wave

Abstract

In order to estimate shear-wave velocity (Vs) structure model at an earthquake motion observation site, a joint inversion technique using observed earthquake motion data and microtremor exploration data is developed. Site amplification factor, receiver function extracted from earthquake motion data and phase velocity of Rayleigh wave extracted from microtremor array observation in Hofu City, Yamaguchi Prefecture are analyzed in this study. Vs structure models up to the seismic bedrock are estimated in the inversion by minimizing the total misfit between the observed and the theoretical data. The Vs structure models that reproduce the observed characteristics are successfully obtained by the proposed joint inversion technique. In order to identify the two-dimensional subsurface structure in Hofu City, the inversion technique is applied to five observation sites by assuming the unified Vs for deep underground model calibrated from the preliminary inversion analysis. The result shows that thickness of the sediment in the central part of the basin is larger than those in other sites, indicating the significant irregularity in the basin.