微動アレー観測による岡崎平野の地盤構造探査

Abstract

The Okazaki Plain located in the Aichi Prefecture is one of the most industrial areas inJapan.The area was damaged several times due to historical earthquakes( 1707 Houei E..,1854 Ansei E. and 1945 Mikawa Earthquake.), and will be attacke again by the Tokai/Tonankai Earthquakake predicted near southern area in subduction zone. Therefore， it is very important to take earthquake disaster prevention measures in this area. In this paper，g eological structure in Okazaki Plain was surveyed by using microtremore array measurements at 10 sites. Dispersion curves were calculated by Spatial Auto-Correlation Meth.od(SPAC) and S-wave velocity dimstribution in soil from surface to rock base were estimated by inversion method. S-wave structures obtained array observations were inspected by H/V spectra of microtremors and earthquake data observed in the same site. Three mmensional structure of soil from surface to seismic basement in Okazaki Plain was obtained comparing with borehole data and structure model studied by the Aichi Prefecture Office. It was clarified that the basement is slanted to north-west direction in the plain and about 800m in depth at Kariya city. The 3-D model obtained in this paper will be useful for estimating strong motions during the future earthquakes.