Relationship of preseismic, coseismic, and postseismic fault ruptures of two large interplate aftershocks of the 2011 Tohoku earthquake with slow-earthquake activity
Relationship of preseismic, coseismic, and postseismic fault ruptures of two large interplate aftershocks of the 2011 Tohoku earthquake with slow-earthquake activity
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DOI：
10.1038/s41598-020-68692-x
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发表时间：
2020-07
影响因子：
4.6
通讯作者：
H. Kubo;T. Nishikawa
中科院分区：
文献类型：
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作者：
H. Kubo;T. Nishikawa
为了提高我们对日本海沟沿着常规地震和慢震之间相互作用的理解，我们研究了慢震活动与日本岩手和茨木海岸外板间地震的震前、同震和震后断层破裂的空间关系，包括2011年东北地震的两次大型板间余震：2011年岩手近海地震（MJMA7.4）和2011年茨木近海地震（MJMA7.6）。我们发现，这些地震的同震破裂与慢震活动区不重叠，而其前震和余震发生在慢震多发区。此外，2011年岩手近海地震与之前的7级地震具有共同的断层破裂特征：同震破裂发生在共同的凹凸体区域，在慢地震活跃区触发了具有多个余震的后滑。在茨木海岸，位于2011年茨木地震同震破裂上倾的俯冲海山上的震颤活动表明，海山对2011年茨木地震同震破裂起到了软屏障的作用。本研究表明，岩手和茨木海岸的大地震具有相似的破裂行为，空间互补分布的同震破裂与慢地震活动和前震和余震活动的内部和周围的慢地震多发区。这一信息对于考虑未来沿着日本海沟的大地震是有用的。
To improve our understanding of the interactions between regular and slow earthquakes along the Japan Trench, we investigated the spatial relationship of slow-earthquake activity with the preseismic, coseismic, and postseismic fault ruptures of interplate earthquakes off the Iwate and Ibaraki coasts, Japan, including two large interplate aftershocks of the 2011 Tohoku earthquake: the 2011 off Iwate earthquake (MJMA7.4) and the 2011 off Ibaraki earthquake (MJMA7.6). We found that the coseismic ruptures of these earthquakes did not overlap with the active areas of slow earthquakes, while their foreshocks and aftershocks occurred in slow-earthquake-prone areas. Moreover, the 2011 off Iwate earthquake and the previous M7-class events shared common fault rupture characteristics: coseismic rupture occurred in a common asperity area, and afterslip with many aftershocks was triggered in the active area of slow earthquakes. Off the Ibaraki coast, tremor activity on a subducting seamount located updip of the coseismic rupture of the 2011 off Ibaraki earthquake implies that the seamount acted as a soft barrier to the coseismic rupture of the 2011 off Ibaraki earthquake. This study demonstrates that large earthquakes off the Iwate and Ibaraki coasts feature similar rupture behaviors, spatially complementary distributions of coseismic ruptures with slow-earthquake activity and foreshock and aftershock activities within and around slow-earthquake-prone areas. This information is useful in considering future large earthquakes along the Japan Trench.