2011年4月11日福島県浜通りの地震（<I>M</I><SUB>j</SUB>7.0）の震源過程:—強震波形と再決定震源による2枚の断層面の推定—
スポンサーリンク
概要
- 論文の詳細を見る
The rupture process of the April 11, 2011 Fukushima Hamadori earthquake (<I>M</I><SUB>j</SUB> 7.0), which is one of the induced earthquakes by the 2011 Tohoku earthquake (<I>M</I><SUB>w</SUB> 9.0), is investigated using near-field strong motion waveforms. After the Fukushima Hamadori earthquake, distinct normal fault type surface ruptures were recognized in the source area. Those surface ruptures line up along the previously-known fault traces, Idosawa fault and Yunotake fault, which exist about 10km apart each other in echelon. We first apply the iterative decomposition method to confirm that these faults acted at the almost same instant whether or not. Additionally, relocation of hypocenters of aftershocks using double-difference method is performed. These results show that the two normal faults slipped with the delay of about 10 s. Two fault segments are assumed according to those results and the multi time window inversion method is applied to determine detailed rupture process on the faults. As the result, total moment of 1.1×10<SUP>19</SUP>Nm (<I>M</I><SUB>w</SUB> 6.6) and the maximum slip of 2.5m on the Idosawa segment are recovered. The result shows that the Idosawa segment acted first and the Yunotake segment slipped after that. Finally, the static Coulomb failure stress change (ΔCFF) on the Yunotake segment gained by the slip on the Idosawa segment is calculated. The ΔCFF in the large slip area on the Yunotake segment is positive and it suggests that the stress change gained by the Idosawa segment induced the slip on the Yunotake segment.
- 公益社団法人 日本地震学会の論文