Shallow inland earthquakes in NE Japan possibly triggered by the 2011 off the Pacific coast of Tohoku Earthquake
Shallow inland earthquakes in NE Japan possibly triggered by the 2011 off the Pacific coast of Tohoku Earthquake
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DOI：
10.5047/eps.2011.06.027
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发表时间：
2011-09
期刊：
影响因子：
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通讯作者：
T. Okada;Keisuke Yoshida;S. Ueki;J. Nakajima;N. Uchida;T. Matsuzawa;N. Umino;A. Hasegawa;G. F. T. A. O. O. T. 2. N. Earthquake-G.-F.-T.-A.-O.-O.-T.-2.-N.-Earthquake-1419904874
中科院分区：
文献类型：
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作者：
T. Okada;Keisuke Yoshida;S. Ueki;J. Nakajima;N. Uchida;T. Matsuzawa;N. Umino;A. Hasegawa;G. F. T. A. O. O. T. 2. N. Earthquake-G.-F.-T.-A.-O.-O.-T.-2.-N.-Earthquake-1419904874
震源区以西的上覆板块地壳中的浅层地震活动在2011年东北9.0兆瓦地震后显着增加，那次地震打破了太平洋下日本北部以东的板块边界。为了了解地震活动这种独特变化的原因，我们用双差法精确地重新定位了2011年3月11日至4月6日东北地震后发生的几个地震序列的地震震中。利用震源分布来区分这些地震序列的震源机制的断裂面和辅助面。然后，我们计算了2011年9级地震引起的这些断层面上的库仑应力变化。在所有情况下，这些主震后序列在可能断层面上的库仑应力估计变化都是正值。库仑应力正值变化的主要原因是2011年9级地震的大角度逆冲断层降低了地震序列断层面上的正应力。目前的观测结果表明，静应力传递可能触发了这些主震后地震序列。
Shallow seismic activity in the crust of the overriding plate west of the source area increased significantly after the 2011 Mw 9.0 Tohoku earthquake which ruptured the plate boundary to the east off northern Japan beneath the Pacific Ocean. In order to understand the cause of this distinctive change in seismicity, we have precisely relocated earthquake hypocenters for several earthquake sequences that occurred during the period March 11–April 6, 2011, following the Tohoku earthquake by the double-difference method. Hypocenter distributions were used to discriminate the fault plane from the auxiliary plane of the focal mechanisms for those earthquake sequences. We then calculated the Coulomb stress change on those fault planes caused by the 2011 Mw 9 earthquake. In all cases, the estimated Coulomb stress changes at the plausible fault planes for those post-mainshock sequences are positive. The positive Coulomb stress change is mainly due to the reduction of normal stress on the fault plane of the earthquake sequences by the large, low-angle thrust fault responsible for the 2011 Mw 9 earthquake. The present observations suggest that static stress transfer possibly triggered those post-mainshock earthquake sequences.