Prevalence of updip rupture propagation in interplate earthquakes along the Japan trench
Prevalence of updip rupture propagation in interplate earthquakes along the Japan trench
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日本海沟板间地震中上倾破裂传播的普遍性
DOI：
10.1016/j.epsl.2021.117306
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发表时间：
2022
影响因子：
5.3
通讯作者：
Shiqing Xu,
中科院分区：
文献类型：
--
作者：
Keisuke Yoshida;Naoki Uchida;Hisahiko Kubo;Ryota Takagi;Shiqing Xu,
海底地震观测的发展有助于可靠地估计近海地震的破裂方向性。我们使用一个新的海底地震网络（S-网）和在陆地上的台站获得的地震波形，系统地检查沿日本海沟沿着板间地震的破裂方向性。我们估计了206个Mw3.5 -5地震的破裂方向，其中大部分发生在孕震区底部附近。我们发现，大多数地震破裂（> 80%）是定向的，主要是向上倾方向传播。这种倾向有利于上倾破裂不能解释的双材料界面的效果。上倾破裂在资料中的普遍性表明，俯冲带中的地震破裂受深部滑动和流体沿板块界面沿着向上运移的影响。上倾断裂将孕震区底部累积的剪应力重新分配到浅部的大地震斑。此外，上倾断裂可能为更深的流体沿着板块界面进一步向上迁移打开通道。应力重分布和流体向上运移对浅层大逆冲断层地震的发生都有促进作用。
The development of seafloor seismic observations facilitates the reliable estimation of rupture directivities from offshore earthquakes. We used seismic waveforms obtained by a new seafloor seismic network (S-net) and stations on land to systematically examine the rupture directivities of interplate earthquakes along the Japan trench. We estimated the rupture directions of 206 M w 3.5–5 events, most of which occurred near the base of the seismogenic zone. We found that most earthquake ruptures (> 80%) were directional, primarily propagating in the updip direction. This tendency favoring updip rupture cannot be explained by the effect of the bimaterial interface. The prevalence of updip rupture in the data suggests that deep aseismic slip and upward fluid migration along the plate interface affected earthquake ruptures in the subduction zone. The updip ruptures redistributed the accumulated shear stress from the base of the seismogenic zone to shallow large seismic patches. Furthermore, the updip ruptures may open paths for deeper fluids to migrate further upward along the plate interface. Both the stress redistribution and upward fluid migration may facilitate the occurrence of shallow megathrust earthquakes.