Intrinsic and apparent short-time limits for fault healing: Theory, observations, and implications for velocity-dependent friction
Intrinsic and apparent short-time limits for fault healing: Theory, observations, and implications for velocity-dependent friction
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DOI：
10.1029/2005jb004096
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发表时间：
2006-12
影响因子：
--
通讯作者：
M. Nakatani;C. Scholz
中科院分区：
文献类型：
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作者：
M. Nakatani;C. Scholz
[1]摩擦强度随时间变化的愈合过程通常是与时间成对数关系的，在一定的持续时间后称为截止时间。我们从理论上证明了截止时间取决于准静态接触开始时的初始强度。这来自于这样一个事实，即治愈率与当前的强度成反比和指数关系。如果愈合是在施加正常载荷时瞬间达到的最小强度开始的，则将观察到反映潜在物理化学过程的反应速率常数的“固有”截止时间Tcx。一般来说，观察到的截止时间是愈合开始时粗糙的TCx和有效接触时间TINI的总和。因此，在滑动-保持-滑动(SHS)实验中，TINI与在保持之前的滑动中的滑移速度V成反比，预测了两个区域。对于高Vprec(Tini≪Tcx)，观察到的截止时间与Vprec无关，为∼Tcx。对于低Vprec(TINI≫Tcx)，观察到的截止时间是“明显的”，∼TINI与VPIRE成反比。这两个制度都已在实验室数据中得到确认。将目前的截止时间理论结合到速率和状态演化定律中，预测了在有效接触时间为≪Tcx的高速下，稳态的速度依赖性将减小。此外，SHS试验的两个区域由该截止速度划分。这一点也得到了实验室数据的证实。讨论了观测到的自然重复地震的很长截止时间的含义。
[1] The time-dependent healing of frictional strength, whose underlying mechanism may vary, is often logarithmic with time, after a certain time duration called the cutoff time. We theoretically show that the cutoff time depends on the initial strength at the beginning of quasi-stationary contact. This comes from the fact that the healing rate depends negatively and exponentially on the current strength. If healing starts with the minimum strength attained instantaneously upon the application of normal load, “intrinsic” cutoff time tcx, which reflects the reaction rate constant of the underlying physico-chemical process, will be observed. In general, the observed cutoff time is the sum of tcx and the effective contact time tini of asperities at the beginning of the healing. Hence, in slide-hold-slide (SHS) experiments, where tini is inversely proportional to the slip velocity Vprior in the sliding preceding the hold, two regimes are predicted. For high Vprior (tini ≪ tcx), the observed cutoff time is independent of Vprior, being ∼tcx. For low Vprior (tini ≫ tcx), the observed cutoff time is “apparent,” being ∼tini inversely proportional to Vprior. Both regimes have been identified in laboratory data. Incorporation of the present cutoff time theory into the rate and state evolution laws predicts that the velocity dependence of steady state will diminish at high velocities where effective contact time is ≪tcx. Furthermore, the two regimes for SHS tests are divided by this cutoff velocity. This also has been confirmed with laboratory data. Implications on the very long cutoff time observed for natural repeating earthquakes are discussed.