SEGJ Technical Conference

Estimation of S-wave velocity structure of deep sedimentary layer around Lake Biwa using earthquake ground motion records and microtremor data.

Abstract Array measurements of microtremors were conducted at K-NET observation sites around Lake Biwa. The array consists of 4 seismometers with a station spacing of 57.7m to 200m. Rayleigh wave phase velocities were estimated from the array data analysis. We applied a joint inversion method for estimating of a 1D S-wave velocity structure of deep sedimentary layers using S-wave parts of earthquake ground motion records, horizontal-to-vertical spectra of surface wave and phase velocity of Rayleigh wave. The inverted structures of deep sediments are in good agreement with geophysical surveys around Lake Biwa and PS logging data at K-NET sites. These models can explain empirical site amplification factors from earthquake data at K-NET sites. This proposed method is effective for an assessment of site amplification, even though there are few .data of geophysical surveys.