Abstract
Array measurements of microtremors were conducted at K-NET observation sites around Lake Biwa, Japan. The array consists of 4 vertical seismometers with a station spacing of 57.7m to 200m. Rayleigh wave phase velocities at periods from 0.17 to 1 second were estimated from the array data analysis. We applied a joint inversion method of S-wave parts of earthquake ground motion records, horizontal-to-vertical spectra of surface wave and phase velocity of Rayleigh wave for estimating of a 1D S-wave velocity structure of deep sedimentary layers. 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 the K-NET sites. This proposed method is effective for an assessment of site amplification, even though there are few data of geophysical surveys.
