Do faults preserve a record of seismic slip: A second opinion
Do faults preserve a record of seismic slip: A second opinion
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DOI：
10.1016/j.jsg.2015.06.006
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发表时间：
2015-09
影响因子：
3.1
通讯作者：
C. Rowe;W. Ashley Griffith
中科院分区：
文献类型：
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作者：
C. Rowe;W. Ashley Griffith
挖掘出的断层带以无与伦比的空间分辨率提供了对与地震相关的变形过程的深入了解;然而，根据岩石记录中的证据，很难区分地震滑动与缓慢或非地震滑动。15年前，科万（1999）定义了可能保存在岩石记录中的地震滑动属性，他确定假玄武玻璃是在古代断层中发现的过去地震的唯一可靠指标。这一论断是基于摩擦生热模型（Sibson，1975，1986），为快速滑移提供了证据。断层岩研究的重大进展揭示了一系列反应产物，这些产物可用于检测峰值温度低于岩石熔融温度时的摩擦热。此外，在与地震破裂传播尖端相关的极端瞬态应力条件下形成的特征现在可以在岩石记录中识别，并且也是独特的地震特征。因此，假玄武玻璃不再是地震破裂的唯一标志。我们回顾了科万（1999）定义的地震滑动标准，我们认为它们过于狭窄。断层以10 - 4 - 101 m/s的速率滑动几乎肯定是动态的。这意味着在实验中以低至10− 4 m/s的速率再现的特征可能是地震滑动的指示。最后，我们总结了地震滑动的岩石记录，并列出了地震地质学领域目前面临的挑战。
Exhumed fault zones offer insights into deformation processes associated with earthquakes in unparalleled spatial resolution; however it can be difficult to differentiate seismic slip from slow or aseismic slip based on evidence in the rock record. Fifteen years ago, Cowan (1999) defined the attributes of earthquake slip that might be preserved in the rock record, and he identified pseudotachylyte as the only reliable indicator of past earthquakes found in ancient faults. This assertion was based on models of frictional heat production (Sibson, 1975, 1986) providing evidence for fast slip. Significant progress in fault rock studies has revealed a range of reaction products which can be used to detect frictional heating at peak temperatures less than the melt temperature of the rock. In addition, features formed under extreme transient stress conditions associated with the propagating tip of an earthquake rupture can now be recognized in the rock record, and are also uniquely seismic. Thus, pseudotachylyte is no longer the only indicator of fossilized earthquake ruptures.We review the criteria for seismic slip defined by Cowan (1999), and we determine that they are too narrow. Fault slip at rates in the range 10−4−101m/sis almost certainly dynamic. This implies that features reproduced in experiments at rates as low as 10−4m/smay be indicators of seismic slip. We conclude with a summary of the rock record of seismic slip, and lay out the current challenges in the field of earthquake geology.