Laboratory observations of time-dependent frictional strengthening and stress relaxation in natural and synthetic fault gouges
Laboratory observations of time-dependent frictional strengthening and stress relaxation in natural and synthetic fault gouges
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DOI：
10.1002/2015jb012136
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发表时间：
2016-02-01
影响因子：
3.9
通讯作者：
Marone, C.
中科院分区：
文献类型：
--
作者：
Carpenter, B. M.;Ikari, M. J.;Marone, C.
地震破坏后断层强度的震间恢复（愈合）是地震周期的基本要求，并且可能在确定构造断层的稳定性和滑动行为方面发挥着关键作用。我们报告了天然和合成凿岩的时间和滑动相关摩擦强化的实验室测量，以评估矿物学在摩擦强化中的作用。我们在 20MPa 正应力、100% 相对湿度（RH）、大剪应变（类似于 15）和室温条件下，对 9 个天然断层泥和 8 个合成断层泥进行了滑动-保持-滑动（SHS）剪切实验。富含页硅酸盐的岩石显示出最低的摩擦强化率。富含石英和长石的样品表现出中等的摩擦强化率，而富含方解石的凿痕显示出最大的值。我们的研究结果表明：(1) 摩擦强化率和蠕变弛豫率随摩擦强度的变化而变化，(2) 富含页硅酸盐的断层泥具有低强度和愈合特性，可促进稳定的抗震蠕变，(3) 大多数天然断层泥表现出中等的摩擦强化率，与广泛的断层滑动行为一致，(4) 富含方解石的断层岩显示出最高的摩擦强化率、再剪切时的低膨胀值和高摩擦强度，所有这些这将促进地震行为。
Interseismic recovery of fault strength (healing) following earthquake failure is a fundamental requirement of the seismic cycle and likely plays a key role in determining the stability and slip behavior of tectonic faults. We report on laboratory measurements of time- and slip-dependent frictional strengthening for natural and synthetic gouges to evaluate the role of mineralogy in frictional strengthening. We performed slide-hold-slide (SHS) shearing experiments on nine natural fault gouges and eight synthetic gouges at conditions of 20MPa normal stress, 100% relative humidity (RH), large shear strain (similar to 15), and room temperature. Phyllosilicate-rich rocks show the lowest rates of frictional strengthening. Samples rich in quartz and feldspar exhibit intermediate rates of frictional strengthening, and calcite-rich gouges show the largest values. Our results show that (1) the rates of frictional strengthening and creep relaxation scale with frictional strength, (2) phyllosilicate-rich fault gouges have low strength and healing characteristics that promote stable, aseismic creep, (3) most natural fault gouges exhibit intermediate rates of frictional strengthening, consistent with a broad range of fault slip behaviors, and (4) calcite-rich fault rocks show the highest rates of frictional strengthening, low values of dilation upon reshear, and high frictional strengths, all of which would promote seismogenic behavior.