人工地震を用いた地殻構造探査による近畿地方のP波速度構造

Abstract

活断層の深部構造や活断層と地殻構造の関係を明らかにすることを目的として，近畿地方で行われた複数の人工地震探査記録を統合的に解析し，近畿地方広域の地震波速度構造の推定を行った。それぞれの測線が近畿地方北部で交差することを利用し，統一的な構造を求め，最終的には，いくつかの測線に沿う地震波速度構造モデルを得て，近畿地方全体の概略的な地下構造を得た。

In order to estimate strong ground motions and to forecast tsunamis for large earthquakes and to reveal the mechanisms of earthquake occurrence, we analyze four seismic survey records conducted in the Kinki district using refraction analyses and obtain P-wave velocity structures. Comparing the structures with hypocenter distributions, geological map and the locations of active faults, we found close relations among them. Especially, intraplate shallow earthquakes are limited to occur in the layer with P-wave velocities of 5.8-6.4km and the 1995 Kobe Earthquake (Mw6.9) occurred at the place with a steep change of velocity structure.