Release of mineral-bound water prior to subduction tied to shallow seismogenic slip off Sumatra
Release of mineral-bound water prior to subduction tied to shallow seismogenic slip off Sumatra
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DOI：
10.1126/science.aal3429
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发表时间：
2017-05-26
期刊：
影响因子：
56.9
通讯作者：
Zhao, Xixi
中科院分区：
文献类型：
--
作者：
Huepers, Andre;Torres, Marta E.;Zhao, Xixi
在2004年苏门答腊岛-安达曼俯冲地震中，板块边界断层断裂比预期的更接近海沟，增加了地震和海啸的规模。国际海洋发现计划探险362对苏门答腊岛北部近海进入的沉积物进行了采样，揭示了最近在深层沉积物中释放的淡水。热模拟将这种清新与过去900万年来埋藏引起的温度快速上升导致的无定形二氧化硅脱水联系在一起。硅酸盐在板块俯冲之前应该完全脱水，这与目前流行的俯冲地震成因模型不同，后者要求在俯冲过程中产生流体。苏门答腊岛近海的浅层滑动似乎是由深埋的断层沉积的成岩作用加强驱动的，与2011年东北-冲之浅海破裂的成岩作用减弱形成对比，但我们的结果适用于其他沉积较厚的俯冲带，包括那些地震记录有限的地区。
Plate-boundary fault rupture during the 2004 Sumatra-Andaman subduction earthquake extended closer to the trench than expected, increasing earthquake and tsunami size. International Ocean Discovery Program Expedition 362 sampled incoming sediments offshore northern Sumatra, revealing recent release of fresh water within the deep sediments. Thermal modeling links this freshening to amorphous silica dehydration driven by rapid burial-induced temperature increases in the past 9 million years. Complete dehydration of silicates is expected before plate subduction, contrasting with prevailing models for subduction seismogenesis calling for fluid production during subduction. Shallow slip offshore Sumatra appears driven by diagenetic strengthening of deeply buried fault-forming sediments, contrasting with weakening proposed for the shallow Tohoku-Oki 2011 rupture, but our results are applicable to other thickly sedimented subduction zones including those with limited earthquake records.