3D geometry of a plate boundary fault related to the 2016 Off-Mie earthquake in the Nankai subduction zone, Japan
3D geometry of a plate boundary fault related to the 2016 Off-Mie earthquake in the Nankai subduction zone, Japan
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DOI：
10.1016/j.epsl.2017.08.041
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发表时间：
2017-11
影响因子：
5.3
通讯作者：
T. Tsuji;S. Minato;R. Kamei;T. Tsuru;G. Kimura
中科院分区：
文献类型：
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作者：
T. Tsuji;S. Minato;R. Kamei;T. Tsuru;G. Kimura
我们使用最新的地震数据和先进的技术，调查三维断层几何形状的过渡部分耦合到完全耦合板界面内侧的南海海槽关闭纪伊半岛，日本。我们发现，一个温和的倾斜板块边界滑脱厚的俯冲层延伸到整个熊野弧前盆地。2016年4月1日三重岛外地震（Mw6.0）及其余震发生时，板块边界滑脱逐步下降，接近洋壳表面。这个位置也位于一个旧的增生棱柱（14Ma）的沟向边缘下沿沿着纪伊半岛海岸开发。2016年破裂面的走向与增生棱柱中以前活跃的展布断层系统相似。因此，2016年地震及其余震的断层面受到板块界面几何形状以及展布断层的影响。2016年的地震发生在1944年托南凯地震（Mw8.1）等大型板间地震的破裂区域内，尽管2016年的破裂区域比1944年的地震小得多。2016年地震的震源位于较年轻的增生棱柱体（106Ma）下方的底侵序列周围，而1944年大地震的震源则靠近较老的增生棱柱体下方的洋壳表面。断层几何形状和岩性的变化可能会影响板块界面沿着的耦合程度，这种耦合变化可能会阻碍2016年事件中向更深板块界面的滑动传播。
We used recent seismic data and advanced techniques to investigate 3D fault geometry over the transition from the partially coupled to the fully coupled plate interface inboard of the Nankai Trough off the Kii Peninsula, Japan. We found that a gently dipping plate boundary décollement with a thick underthrust layer extends beneath the entire Kumano forearc basin. The 1 April 2016 Off-Mie earthquake (Mw6.0) and its aftershocks occurred, where the plate boundary décollement steps down close to the oceanic crust surface. This location also lies beneath the trenchward edge of an older accretionary prism (∼14 Ma) developed along the coast of the Kii peninsula. The strike of the 2016 rupture plane was similar to that of a formerly active splay fault system in the accretionary prism. Thus, the fault planes of the 2016 earthquake and its aftershocks were influenced by the geometry of the plate interface as well as splay faulting. The 2016 earthquake occurred within the rupture area of large interplate earthquakes such as the 1944 Tonankai earthquake (Mw8.1), although the 2016 rupture area was much smaller than that of the 1944 event. Whereas the hypocenter of the 2016 earthquake was around the underplating sequence beneath the younger accretionary prism (∼6 Ma), the 1944 great earthquake hypocenter was close to oceanic crust surface beneath the older accretionary prism. The variation of fault geometry and lithology may influence the degree of coupling along the plate interface, and such coupling variation could hinder slip propagation toward the deeper plate interface in the 2016 event.