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Fault weakening and earthquake instability by powder lubrication

机译：通过粉末润滑来减弱故障和地震不稳定

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摘要

Earthquake instability has long been attributed to fault weakening during accelerated slip, and a central question of earthquake physics is identifying the mechanisms that control this weakening. Even with much experimental effort, the weakening mechanisms have remained enigmatic. Here we present evidence for dynamic weakening of experimental faults that are sheared at velocities approaching earthquake slip rates. The experimental faults, which were made of room-dry, solid granite blocks, quickly wore to form a fine-grain rock powder known as gouge. At modest slip velocities of 10-60 mm s~(-1), this newly formed gouge organized itself into a thin deforming layer that reduced the fault's strength by a factor of 2-3. After slip, the gouge rapidly 'aged' and the fault regained its strength in a matter of hours to days. Therefore, only newly formed gouge can weaken the experimental faults. Dynamic gouge formation is expected to be a common and effective mechanism of earthquake instability in the brittle crust as (1) gouge always forms during fault slip; (2) fault-gouge behaves similarly to industrial powder lubricants; (3) dynamic gouge formation explains various significant earthquake properties; and (4) gouge lubricant can form for a wide range of fault configurations, compositions and temperatures.
机译：长期以来，地震的不稳定性一直归因于加速滑动过程中的断层减弱，而地震物理学的中心问题是确定控制这种减弱的机制。即使进行了许多实验性的努力，其减弱机制仍然是未知的。在这里，我们提供了对实验断层进行动态削弱的证据，这些断层以接近地震滑动速率的速度剪切。实验断层是由干燥的固态花岗岩块制成的，很快就磨损形成了细粉状的岩石粉，称为凿子。在10-60 mm s〜（-1）的适度滑移速度下，这种新形成的凿子将自身组织成一个薄的变形层，使断层的强度降低了2-3倍。滑移后，凿子迅速“老化”，断层在几小时到几天内恢复了强度。因此，只有新形成的凿子才能减弱实验断层。动态断层泥形成有望成为脆性地壳地震失稳的常见有效机制，因为（1）在断层滑动过程中总是形成断层泥； （2）断线仪的性能类似于工业粉末润滑剂； （3）动态气孔形成解释了各种重要的地震特性； （4）凿岩润滑剂会形成各种故障构造，成分和温度。

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  • 来源
    《Nature》 |2010年第7314期|P.452-455|共4页
  • 作者

    Zeev Reches; David A. Lockner;

  • 作者单位

    School of Geology and Geophysics, University of Oklahoma, 100 East Boyd Street, Norman, Oklahoma, USA;

    rnUS Geological Survey, 345 Middlefield Road, Menlo Park, California 94025, USA;

  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);美国《生物学医学文摘》(MEDLINE);美国《化学文摘》(CA);
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  • 正文语种 eng
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