SEGJ Technical Conference

Estimation of S-wave velocity structure in Ichinoseki city, Iwate Prefectuer by microtremor surveys using a miniature array

Abstract We carried out microtremor surveys using a miniature array in central Ichinoseki City, Iwate Prefecture. Microtremor observations were done at 44 sites in Ichinoseki City. We estimated S-wave velocity structures by using phase velocities of Rayleigh wave. And, we compared the questionnaire seismic intensities with estimated S-wave velocity structures. As a result, S-wave velocity is very slow about 100m/s at a depth of 0~2m in Akogi area and Yamame area of Ichinoseki City. This study found that there is a negative correlation between the questionnaire seismic intensities and estimated S-wave velocity structures. The result shows heterogeneous shallow S-wave velocity distribution in Ichinoseki City effects on strong motions. The microtremor survey is effective for estimating shallow S-wave velocity structures.