Friction falls towards zero in quartz rock as slip velocity approaches seismic rates
Friction falls towards zero in quartz rock as slip velocity approaches seismic rates
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DOI：
10.1038/nature02249
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发表时间：
2004-01-29
期刊：
影响因子：
64.8
通讯作者：
Tullis, TE
中科院分区：
文献类型：
--
作者：
Di Toro, G;Goldsby, DL;Tullis, TE
地震力学中一个重要的未解决的问题是确定地震时地壳断层的滑动阻力（1）。同震滑动阻力的知识对于理解剪切应力降低的幅度以及地震期间可能发生的近断层加速度至关重要，这会影响地震能够造成的破坏量。特别是，一个长期未解决的问题是主要断层（2-6）的强度明显较低，这可能是由于同震摩擦阻力较低（3）造成的。最近在实验室条件下模拟了滑动速度高达3 mm s（-1）时岩石的摩擦特性和大地震的滑动位移特性（7）。在这里，我们报告的石英岩石的数据表明，一个非凡的渐进减少摩擦阻力增加滑动速度超过1毫米秒（-1）。这种减少可以外推到在地震滑动速率接近1 m s（-1）时摩擦力为零，这似乎是由于断层表面形成了一层薄薄的硅胶层：它可以解释地震期间主要断层强度较低的原因。
An important unsolved problem in earthquake mechanics is to determine the resistance to slip on faults in the Earth's crust during earthquakes(1). Knowledge of coseismic slip resistance is critical for understanding the magnitude of shear-stress reduction and hence the near-fault acceleration that can occur during earthquakes, which affects the amount of damage that earthquakes are capable of causing. In particular, a long-unresolved problem is the apparently low strength of major faults(2-6), which may be caused by low coseismic frictional resistance(3). The frictional properties of rocks at slip velocities up to 3 mm s(-1) and for slip displacements characteristic of large earthquakes have been recently simulated under laboratory conditions(7). Here we report data on quartz rocks that indicate an extraordinary progressive decrease in frictional resistance with increasing slip velocity above 1 mm s(-1). This reduction extrapolates to zero friction at seismic slip rates of similar to1m s(-1), and appears to be due to the formation of a thin layer of silica gel on the fault surface: it may explain the low strength of major faults during earthquakes.