Dynamic weakening and amorphization in serpentinite during laboratory earthquakes
Dynamic weakening and amorphization in serpentinite during laboratory earthquakes
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DOI：
10.1130/g37932.1
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发表时间：
2016-08-01
期刊：
影响因子：
5.8
通讯作者：
Schubnel, Alexandre
中科院分区：
文献类型：
--
作者：
Brantut, Nicolas;Passelegue, Francois X.;Schubnel, Alexandre
蛇纹岩的力学性质是我们理解俯冲带地震破裂动力学，特别是中深地震的关键因素。在这里，我们对天然叶蛇纹石蛇纹岩进行了剪切破裂实验，结果表明，在自发动态破裂传播过程中，摩擦力达到近零值。快速同震滑动（> 1 m/s），虽然发生在短距离（< 1 mm），但会导致沿滑动表面沿着微尺度粗糙体的显著过热，足以产生表面非晶化和可能的熔融。叶蛇纹石脱水发生在断层壁，这留下了部分非晶化的材料。产生的水可能有助于生产低粘度加压熔体，解释了在某些事件中观察到的接近零的动摩擦水平。蛇纹岩中快速而剧烈的动力学弱化可能是促进俯冲带中等深度地震传播的关键过程。
The mechanical properties of serpentinites are key factors in our understanding of the dynamics of earthquake ruptures in subduction zones, especially intermediate-depth earthquakes. Here, we performed shear rupture experiments on natural antigorite serpentinite, which showed that friction reaches near-zero values during spontaneous dynamic rupture propagation. Rapid coseismic slip (> 1 m/s), although it occurs over short distances (< 1 mm), induces significant overheating of microscale asperities along the sliding surface, sufficient to produce surface amorphization and likely some melting. Antigorite dehydration occurs in the fault walls, which leaves a partially amorphized material. The water generated potentially contributes to the production of a low-viscosity pressurized melt, explaining the near-zero dynamic friction levels observed in some events. The rapid and dramatic dynamic weakening in serpentinite might be a key process facilitating the propagation of earthquakes at intermediate depths in subduction zones.