Seismicity near the hypocenter of the 2011 off the Pacific coast of Tohoku earthquake deduced by using ocean bottom seismographic data
Seismicity near the hypocenter of the 2011 off the Pacific coast of Tohoku earthquake deduced by using ocean bottom seismographic data
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DOI：
10.5047/eps.2012.04.010
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发表时间：
2011-12
期刊：
影响因子：
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通讯作者：
Kensuke Suzuki;R. Hino;Y. Ito;Y. Yamamoto;Syuichi Suzuki;H. Fujimoto;M. Shinohara;Masao Abe;Yoshiharu Kawaharada;Y. Hasegawa;Y. Kaneda
中科院分区：
文献类型：
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作者：
Kensuke Suzuki;R. Hino;Y. Ito;Y. Yamamoto;Syuichi Suzuki;H. Fujimoto;M. Shinohara;Masao Abe;Yoshiharu Kawaharada;Y. Hasegawa;Y. Kaneda
我们将2011年太平洋沿岸东北地震（9.0级）的前震、主震和余震的震源重新定位在地震破裂开始的日本海沟中部。部署在该地区的海底地震仪（OBSs）记录了地震，这些数据提供了震源分布的改进图像。主震震源较日本气象厅（JMA）报告的位置略微向西移动，位于板块边界和上覆板块的莫霍线交界处附近。前震地震活动主要发生在主震震源的沟向一侧，即太平洋板块与岛弧地壳接触的地方。前震在最大前震（里氏7.3级，主震发生前2天）约30 km处的孕震带上倾极限处被激活。7.3级地震发生后，观察到强烈的板块间地震活动，并伴有震中向主震震源迁移。震源深度分布对M-9主震的响应有明显变化。在同震大滑动区，沿板块边界的地震几乎不存在，而沿板块边界的地震在上下板块都有所增加。
We relocated hypocenters of the foreshock, mainshock, and aftershocks of the 2011 off the Pacific coast of Tohoku earthquake (M 9.0) in the middle part of the Japan Trench where the earthquake rupture initiated. Ocean Bottom Seismographs (OBSs), deployed in the area, recorded the earthquakes and these data provide improved images of the hypocenter distribution. The mainshock hypocenter was relocated slightly westward from that reported by Japan Meteorological Agency (JMA), placing it near the intersection between the plate boundary and the Moho of the overriding plate. The foreshock seismicity mainly occurred on the trenchward side of the mainshock hypocenter, where the Pacific slab contacts the island arc crust. The foreshocks were initially activated at the up-dip limit of the seismogenic zone ~30 km trenchward of the largest foreshock (M 7.3, two days before the mainshock). After the M-7.3 earthquake, intense interplate seismicity, accompanied by epicenters migrating toward the mainshock hypocenter, was observed. The focal depth distribution changed significantly in response to the M-9 mainshock. Earthquakes along the plate boundary were almost non-existent in the area of huge coseismic slip, whereas earthquakes off the boundary increased in numbers in both the upper and the lower plates.