The catastrophic 2004 Sumatra‐Andaman Mw9.1 earthquake associated with destructive tsunamis has characterized Sumatra as one of the most dangerous convergence zones. Nevertheless, the effects of the thermohydrous state on the strongly coupled megathrust of the incoming plate remain enigmatic. By using a three‐dimensional (3‐D) thermomechanical model to compute the temperature variation and the complicated phase transition process of the water‐bearing descending plate which generates unstable thrust slips, we find that Sumatran earthquakes at varying depths are likely under the control of the inter or intraplate hydrothermal regime, which occurs in or close to the petrological metamorphism transition area. The slab dehydration of the water‐rich mid‐ocean‐ridge basalts (MORB) and the ultramafic rocks in the oceanic lithosphere releases a large amount of fluid to the continental wedge and further facilitates arc magmatism. The fluids are prone to upwelling following the subduction channel along the plate interface and thus contribute to the clustering of earthquakes updip of the dehydration front beneath offshore Sumatra. Brittle failure and dehydration embrittlement at depth, along with the temperature differences caused by variant slab geometry, are conjectured to greatly influence the occurrence of fast and slow earthquakes in Sumatra.

中文翻译：

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苏门答腊板坯脱水：对快和慢地震和岩浆作用的影响

与破坏性海啸相关的2004年苏门答腊-安达曼Mw9.1灾难性地震将苏门答腊岛定为最危险的汇合区之一。然而，热水状态对进入板的强耦合兆推力的影响仍然是未知的。通过使用三维（3D）热力学模型来计算含水下降板的温度变化和复杂的相变过程，该过程会产生不稳定的推力滑动，我们发现在不同深度下的苏门答腊地震很可能受到控制板内或板内热液状态的一种，它发生在岩石变质作用过渡区中或附近。富含水的中海脊玄武岩（MORB）和超岩石质岩石的平板脱水使大量的流体释放到大陆楔形体上，进一步促进了弧岩浆作用。流体易于沿着板块界面沿俯冲通道上升，因此导致了苏门答腊近海下方脱水锋面地震上倾的聚集。推测深部的脆性破坏和脱水脆化，以及由不同的平板几何形状引起的温差，将极大地影响苏门答腊快速地震和慢速地震的发生。流体易于沿着板块界面沿俯冲通道上升，因此导致了苏门答腊近海下方脱水锋面地震上倾的聚集。推测深部的脆性破坏和脱水脆化，以及由不同的平板几何形状引起的温差，将极大地影响苏门答腊快速地震和慢速地震的发生。流体易于沿着板块界面沿俯冲通道上升流，因此有助于在苏门答腊近海下方的脱水前缘向上聚集地震。推测深部的脆性破坏和脱水脆化，以及由不同的平板几何形状引起的温差，将极大地影响苏门答腊快速地震和慢速地震的发生。