Episodic slow slip events in the Japan subduction zone before the 2011 Tohoku-Oki earthquake
Episodic slow slip events in the Japan subduction zone before the 2011 Tohoku-Oki earthquake
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DOI：
10.1016/j.tecto.2012.08.022
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发表时间：
2013-07-17
期刊：
影响因子：
2.9
通讯作者：
Ashi, Juichiro
中科院分区：
文献类型：
--
作者：
Ito, Yoshihiro;Hino, Ryota;Ashi, Juichiro
我们描述了2011年东北冲地震前发生的两个瞬态慢滑事件。第一次短暂的地壳变形发生在2008年11月的一个星期内，使用海底压力计和岸上的体积应变计同时记录;这种变形被解释为M6.8幕式缓慢滑动事件。第二次持续时间超过1个月，于2011年2月，就在2011年东北冲地震之前观测到，该事件的矩震级达到7.0。这两次地震分别发生在M6.1（2008年12月）和M7.3（2011年3月9日）的板间地震之前，后者是2011年东北冲地震的最大前震。我们的研究结果表明，这些缓慢的滑动事件引起的剪切应力的增加，这反过来又引发了板间地震。断层上的慢滑事件震源区也位于2011年地震巨大同震滑动区的下倾部分。这表明幕式慢滑和地震行为发生在同一部分的巨型逆冲断层，这表明，断层经历滑动在慢滑事件也可以破裂地震。(C)2012爱思唯尔有限公司版权所有。
We describe two transient slow slip events that occurred before the 2011 Tohoku-Oki earthquake. The first transient crustal deformation, which occurred over a period of a week in November 2008, was recorded simultaneously using ocean-bottom pressure gauges and an on-shore volumetric strainmeter; this deformation has been interpreted as being an M6.8 episodic slow slip event. The second had a duration exceeding 1 month and was observed in February 2011, just before the 2011 Tohoku-Oki earthquake; the moment magnitude of this event reached 7.0. The two events preceded interplate earthquakes of magnitudes M6.1 (December 2008) and M7.3 (March 9, 2011), respectively; the latter is the largest foreshock of the 2011 Tohoku-Oki earthquake. Our findings indicate that these slow slip events induced increases in shear stress, which in turn triggered the interplate earthquakes. The slow slip event source area on the fault is also located within the downdip portion of the huge-coseismic-slip area of the 2011 earthquake. This demonstrates episodic slow slip and seismic behavior occurring on the same portions of the megathrust fault, suggesting that the faults undergo slip in slow slip events can also rupture seismically. (C) 2012 Elsevier B.V. All rights reserved.