The strength of earthquake-generating faults
The strength of earthquake-generating faults
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DOI：
10.1144/jgs2017-037
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发表时间：
2017-08
影响因子：
2.7
通讯作者：
A. Copley
中科院分区：
文献类型：
--
作者：
A. Copley
本文总结了用于研究活动发震断层强度的观测和方法。基于一系列地球物理和地质观测的间接推论表明，断层在剪切应力小于c. 50 MPa，相当于有效摩擦系数小于0.3，可能低至0.05。这些低水平的有效摩擦可能是高孔隙流体压力（可能是局部的或瞬时的）和富含层状硅酸盐的断层岩的摩擦特性共同作用的结果。在大洋外隆形成的新断层的倾角意味着，内在的低摩擦断层岩必须控制至少在该设置的断层强度。当结合从钻孔研究和一些实验室测量推断出的更高的断层强度时，观测结果与嵌入在强环境中的弱断层最一致，为断层复活的流行提供了明确的原因。然而，形成新断层所需的条件，以及断层愈合程度随时间变化明显的原因，仍然是未知的。
This paper summarizes the observations and methods that have been used to study the strength of active earthquake-generating (seismogenic) faults. Indirect inferences based upon a range of geophysical and geological observations suggest that faults fail in earthquakes at shear stresses of less than c. 50 MPa, equivalent to effective coefficients of friction of less than 0.3, and possibly as low as 0.05. These low levels of effective friction are likely to be the result of a combination of high pore fluid pressures, which could be local or transient, and the frictional properties of phyllosilicate-rich fault rocks. The dip angles of new faults forming in oceanic outer rises imply that intrinsically low-friction fault rocks must control the fault strength in at least that setting. When combined with the much higher fault strengths inferred from borehole studies and some laboratory measurements, the observations are most consistent with weak faults embedded in strong surroundings, providing a clear reason for the prevalence of fault reactivation. However, the conditions required for the formation of new faults, and the reasons for an apparent wide variability in the degree of fault healing through time, remain unknown.