An inhomogeneous across-slab conduit controlled by intraslab stress heterogeneity in the Nankai subduction zone
An inhomogeneous across-slab conduit controlled by intraslab stress heterogeneity in the Nankai subduction zone
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DOI：
10.1038/s41598-018-38142-w
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发表时间：
2019-01
影响因子：
4.6
通讯作者：
M. Otsubo;A. Miyakawa;I. Katayama;K. Okazaki
中科院分区：
文献类型：
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作者：
M. Otsubo;A. Miyakawa;I. Katayama;K. Okazaki
在日本西南部南海海槽俯冲带的下倾部分，从锁定断层到连续蠕动断层的过渡带中同时发生非火山性的深低频地震和慢滑动事件。这些慢地震的发生是不连续的沿着沟，并归因于在板块边界的高孔隙压力的影响。在这里，我们表明，在intraslab应力的空间变化可能会控制流体从俯冲菲律宾海板块的板块边界迁移。三轴正断层应力，检测到的应力张量反演使用震源机制在板，控制各向异性渗透率的趋势NNW-SSE近水平从俯冲菲律宾海板板块边界。俯冲菲律宾海板片受空间应力不均匀性控制的渗透率不均匀性控制了板片内流体通道。这一假说与慢震的空间不均匀性和3 He/4 He比值的空间不均匀性是一致的。
Nonvolcanic, deep low-frequency tremors and slow-slip events occur simultaneously in the transition zone from locked to continuously creeping fault in the down-dip portion of the Nankai Trough subduction zone, southwestern Japan. The occurrence of these slow earthquakes is discontinuous along the trench and attributed to the effect of high pore pressures at the plate boundary. Here, we show that spatial variations in intraslab stress may control fluid migration from the subducted Philippine Sea slab to the plate boundary. The triaxial normal faulting stress, detected by stress tensor inversion using focal mechanisms in the slab, controls anisotropically permeability that trends NNW–SSE subhorizontally from the subducted Philippine Sea slab to the plate boundary. The inhomogeneous permeability controlled by spatial stress heterogeneities in the subducted Philippine Sea slab controls the intraslab fluid pathway. This hypothesis is consistent with the spatial heterogeneity of slow earthquakes and3He/4He ratio distributions.