Locking of the Chile subduction zone controlled by fluid pressure before the 2010 earthquake
Locking of the Chile subduction zone controlled by fluid pressure before the 2010 earthquake
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DOI：
10.1038/ngeo2102
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发表时间：
2014-04
影响因子：
18.3
通讯作者：
M. Moreno;C. Haberland;O. Oncken;A. Rietbrock;S. Angiboust;O. Heidbach
中科院分区：
文献类型：
--
作者：
M. Moreno;C. Haberland;O. Oncken;A. Rietbrock;S. Angiboust;O. Heidbach
俯冲带强地震潜在规模和复发时间的约束来自大地震间隔期间下降板块和上覆板块之间的锁定程度。在许多情况下，这种震间锁定程度与大地震期间的滑动有关，或归因于板块界面处流体含量的变化。在这里，我们使用大地测量和地震学数据，探讨2010年智利8.8级地震期间破裂的俯冲界面处的孔隙流体压力和锁定模式之间的联系。高分辨率三维地震层析成像揭示了地震P波与S波速度之比（Vp/Vs）沿俯冲带界面沿着的变化。高Vp/Vsdomains，解释为孔隙流体压力升高的区域，在空间上与板块界面锁定不良和滑动抗震的部分相关。相比之下，低Vp/Vs域，解释为较低的孔隙流体压力区，与锁定部分的板块界面，不稳定的滑动和地震发生。孔隙流体压力的变化是由热液蚀变海洋断裂带的俯冲和脱水引起的。我们的结论是，孔隙流体压力在板块界面的变化控制地震间锁定的程度，因此，大地震破裂的滑动分布。
Constraints on the potential size and recurrence time of strong subduction-zone earthquakes come from the degree of locking between the down-going and overriding plates, in the period between large earthquakes. In many cases, this interseismic locking degree correlates with slip during large earthquakes,,,or is attributed to variations in fluid content at the plate interface. Here we use geodetic and seismological data to explore the links between pore-fluid pressure and locking patterns at the subduction interface ruptured during the magnitude 8.8 Chile earthquake in 2010. High-resolution three-dimensional seismic tomography reveals variations in the ratio of seismic P- to S-wave velocities (Vp/Vs) along the length of the subduction-zone interface. HighVp/Vsdomains, interpreted as zones of elevated pore-fluid pressure, correlate spatially with parts of the plate interface that are poorly locked and slip aseismically. In contrast, lowVp/Vsdomains, interpreted as zones of lower pore-fluid pressure, correlate with locked parts of the plate interface, where unstable slip and earthquakes occur. Variations in pore-fluid pressure are caused by the subduction and dehydration of a hydrothermally altered oceanic fracture zone. We conclude that variations in pore-fluid pressure at the plate interface control the degree of interseismic locking and therefore the slip distribution of large earthquake ruptures.