微動アレー観測による岡崎平野北部の地下構造探査

Abstract

The Okazaki Plain located in the Aichi Prefecture is one of most industrial area eminent Japan, and also the region where severe damages are predicted by the future large earthquakes such as Tokai / Tohnankai earthquakes. An geological structure survey was performed by the Aichi Prefecture in 2001-2004. However, the detail structure of the northern part of the Plain does not have understood yet by poor data of surveys. Therefore, the microtremor array observations were performed to obtain detail structure in this area. In this study, the SPAC method was used for obtaining dispersion curve of Rayleigh wave. S-wave velocity structures at 11 sites were estimated by inversion technique GA. The surveyed results obtained in this study were similar to the results by Aichi Prefecture. Three dimensional structure including basement rock was estimated by integrated the data by the conventional findings (Borehole data and Aichi Prefecture, 2001-2004) and microtremor array survey (Hibi et al, 2005). The depth of basement rock is shallow in south-eastern area and deep in north-western area, that is, the basement inclines toward north-western direction. Earthquake records were estimated by using the structure obtained in this study and compared with ones recorded. The structures obtained in this study can explain the observed records.