Extremely early recurrence of intraplate fault rupture following the Tohoku-Oki earthquake
Extremely early recurrence of intraplate fault rupture following the Tohoku-Oki earthquake
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DOI：
10.1038/s41561-018-0201-x
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发表时间：
2018-08
影响因子：
18.3
通讯作者：
Y. Fukushima;S. Toda;S. Miura;D. Ishimura;J. Fukuda;T. Demachi;K. Tachibana
中科院分区：
文献类型：
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作者：
Y. Fukushima;S. Toda;S. Miura;D. Ishimura;J. Fukuda;T. Demachi;K. Tachibana
地球上地壳断层上的板内地震通常在1000年或更长时间内重复发生。2011年东北冲地震引发了日本关东北部的板内地震，包括2011年3月19日和2016年12月28日相继发生的两次6级地震。在这里，我们使用卫星雷达和全球导航卫星系统捕获的位移来显示，这两次地震破裂的是一个相同的断层。详细的断层滑动模拟表明，两次地震的形变数据可以很好地解释沿着共同的断层几何形状的滑动，并且断层上的大部分滑动区域是重叠的。应变分析表明，第一次6级地震之后发生了极大的震后变形。这种变形与6级断裂区周围的余滑是一致的，这反过来又重建了断层上的剪应力，从而使下一次地震成为可能。我们推测，2011年东北大地震的震后快速大变形促进了这种余滑，并使第二次地震在短短5.8年内再次发生。这项研究提出了一种机制来解释在古震复发研究中观察到的极端时间聚集现象。
Intraplate earthquakes on a fault in Earth’s upper crust commonly recur in 1,000 years or longer. The 2011 M9 Tohoku-Oki earthquake triggered the activation of intraplate earthquakes in northern Kanto, Japan, including two M6 events on 19 March 2011 and 28 December 2016 located near one another. Here we use displacements captured by satellite radar and the Global Navigation Satellite System to show that the two earthquakes ruptured an identical fault. Detailed fault slip modelling shows that the deformation data for the two earthquakes are well explained by slip along a common fault geometry, and that the majority of the slipped area on the fault overlaps. Strain analysis reveals that the first M6 earthquake was followed by exceptionally large postseismic deformation. Such deformation is consistent with afterslip around the M6 rupture area, which in turn rebuilds the shear stress on the fault enabling the next earthquake. We infer that the rapid and large postseismic deformation of the 2011 Tohoku-Oki earthquake promoted such afterslip and made the second earthquake recur in just 5.8 years. This study suggests a mechanism to explain observations of extreme temporal clustering in palaeoseismic earthquake recurrence studies.