The Mw 9.0 northeast Japan earthquake: total rupture of a basement asperity
The Mw 9.0 northeast Japan earthquake: total rupture of a basement asperity
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DOI：
10.1111/j.1365-246x.2011.05368.x
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发表时间：
2012-04
影响因子：
2.8
通讯作者：
C. Hashimoto;A. Noda;M. Matsu'ura
中科院分区：
文献类型：
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作者：
C. Hashimoto;A. Noda;M. Matsu'ura
2011年3月11日，在北美板块和太平洋板块的交界处，日本东北部海域发生了Mw 9.0级地震。板间地震的发生可以看作是震源区滑动亏损逐渐增大所积累的构造应力的突然释放。对东北大地震前地震平静期(1996-2000年)的GPS速度资料进行的反演分析表明，沿千岛-日本海沟南部的NA-PA板块界面上存在5个显著的滑动亏损区。我们用同样的方法分析了东北地震的同震GPS位移资料，得到了南部宫城和福岛两个震间滑动缺陷区的同震滑动扩展的双峰分布。最大滑移量宫城缺陷区为32m，福岛缺陷区仅为7m。在过去的两个世纪里，每隔40年就会发生一次具有约3m同震滑动的正常大地震，宫城-秋木滑动缺陷区的极大同震滑动表明，一个300公里长的基底凹凸体在小得多的局部凹凸体下完全破裂。
SUMMARY The Mw 9.0 off northeast Japan (Tohoku-oki) earthquake occurred on 2011 March 11 at the interface between the North American (NA) and Pacific (PA) plates. The occurrence of interplate earthquakes can be regarded as the sudden release of tectonic stress accumulated by the interseismic gradual increase of slip deficit in source regions. The inversion analysis of GPS velocity data for a seismically calm period (1996–2000) before the Tohoku-oki earthquake has revealed the existence of five remarkable slip-deficit zones distributed on the NA–PA plate interface along the southern Kuril-Japan trench. We analysed coseismic GPS displacement data for the Tohoku-oki earthquake with the same inversion method, and obtained the bimodal distribution of coseismic slip spreading over the southern two, Miyagi-oki and Fukushima-oki, interseismic slip-deficit zones. The maximum slip is 32 m for the Miyagi-oki slip-deficit zone but only 7 m for the Fukushima-oki slip-deficit zone. The extraordinarily large coseismic slip in the Miyagi-oki slip-deficit zone, where ordinarily large earthquakes with about 3 m coseismic slips have repeated every 40 yr in the past two centuries, suggests the total rupture of a 300-km-long basement asperity underlying much smaller-scale local asperities.