Slow Earthquakes Illuminating Interplate Coupling Heterogeneities in Subduction Zones
Slow Earthquakes Illuminating Interplate Coupling Heterogeneities in Subduction Zones
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DOI：
10.1029/2020gl088089
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发表时间：
2020-07-28
影响因子：
5.2
通讯作者：
Noda, Akemi
中科院分区：
文献类型：
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作者：
Baba, Satoru;Takemura, Shunsuke;Noda, Akemi
慢震主要分布在大逆冲断层地震的孕震区附近，并可预测两类地震之间的关系。我们研究了日本周围的甚低频地震（VLFEs）的活动，被归类为慢地震的一种类型，因为它们有可能澄清板块边界的详细时空滑动行为。浅部VLFE活动率沿沿着槽轴分布不均匀，与板间耦合比的空间分布呈负相关关系，而深部VLFE仅分布在弱耦合区，活动率的空间变化较小。此外，VLFE主要由低地震速度异常承载。因此，由于板间耦合弱的区域内的高孔隙流体压力，有效应力降低可以触发慢地震，它们的活动可以是板间滑动行为的指示。
Slow earthquakes are mainly distributed in the vicinity of seismogenic zones of megathrust earthquakes and relationships between both types of earthquakes are expected. We examined the activity of very low frequency earthquakes (VLFEs), classified as one type of slow earthquake, around Japan because they have the potential to clarify detailed spatiotemporal slip behaviors at the plate boundaries. The distribution of the shallow VLFE activity rate is heterogeneous along trench axes and exhibits an anticorrelation relationship with the spatial distribution of the interplate coupling ratio, whereas deep VLFEs are distributed only in weakly coupled areas, and the spatial variation of the activity rate is small. Furthermore, VLFEs are mainly hosted by low seismic velocity anomalies. Thus, slow earthquakes can be triggered by decreased effective stress due to the high pore fluid pressure within regions with weak interplate coupling, and their activity can be an indicator of interplate slip behavior.