兵庫県南部地震に伴う応力変化

断層モデルによるクーロン破壊関数の変化の計算と地震活動の変化との比較

抄録

We calculate static stress changes for the fault model derived from geodetic data before and after the magnitude=7.2 Kobe earthquake of January 17, 1995 in order to examine the possible correlation between changes in seismicity in the surrounding regions and stress changes.
The Coulomb failure function (CFF) for right lateral slip on NE-SW or nearly E-W trending vertical faults may increase in the north of the Arima-Takatsuki Tectonic Line, where the activation of seismicity is observed. CFF for left lateral slip on NW-SE trending vertical faults may also increase around the Yamasaki fault, northwest of Kobe, which is consistent with the activation of seismicity there. In the northern Kinki district, where seismicity became a little bit lower, CFF is predicted to decrease. CFF may change a little in the Wakayama region, where significant seismicity changes are not observed.
The Kobe earthquake may have loaded the Arima-Takatsuki Tectonic Line, segments of the Median Tectonic Line in Wakayama and Tokushima and westward dipping thrusts in the Osaka plane. Therefore we should carefully monitor the crustal activity around these tectonic lines.