Tomography of the Source Area of the 1995 Kobe Earthquake: Evidence for Fluids at the Hypocenter?

Abstract

Seismic tomography revealed a low seismic velocity (-5%) and high Poisson's ratio (+6%) anomaly covering about 300 square kilometers at the hypocenter of the 17 January 1995, magnitude 7.2, Kobe earthquake in Japan. This anomaly may be due to an overpressurized, fluid-filled, fractured rock matrix that contributed to the initiation of the Kobe earthquake.