Stress triggering of large earthquakes complicated by transient aseismic slip episodes
Stress triggering of large earthquakes complicated by transient aseismic slip episodes
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DOI：
10.1029/2008jb006125
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发表时间：
2008-12
影响因子：
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通讯作者：
I. Cho;Taku Tada;Y. Kuwahara
中科院分区：
文献类型：
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作者：
I. Cho;Taku Tada;Y. Kuwahara
[1]我们研究了附近地震引起的静态应力变化如何扰动断层上的滑动过程和下一次地震的时间。为此目的，我们在一个二维的，半无限的和弹性的介质，部分稳定和部分不稳定的速率和状态依赖的摩擦法数值模拟逆断层。在没有应力变化的情况下，稳定滑动从深部摩擦稳定带向外扩展，并在震间阶段继续向上倾扩展。非地震滑动幕（ASES）在稳定滑动区内自发发展，并准周期性重复。当稳定的滑动已经蔓延超过一定的临界长度（成核长度）以上的摩擦稳定区，其中一个ASES经历快速建设和雪崩到高速地震滑动。当一个阶梯状的应力变化介入时，振幅较大的ASE会出现，并以类似于它们的自发对应物的方式演化，直到其中一个崩塌成地震。如果应力变化在地震周期中既不早也不晚，基本情况如下：延迟应力阶跃，无论是正的还是负的，都会延迟ASE序列的时间，从而延迟下一次地震。然而，当应力阶跃延迟到一定程度以上时，较早的ASE会演变成地震，不连续地推进其时间。只有在地震周期的最后阶段，正应力阶跃才系统地提前下一次地震，而负应力阶跃则系统地延迟下一次地震。
[1] We investigate how a static stress change, caused by a nearby earthquake, perturbs sliding processes on a fault and the time to the next earthquake. For this purpose, we model numerically a reverse fault in a two-dimensional, semi-infinite and elastic medium, partly stable and partly unstable under a rate- and state-dependent friction law. When no stress change intervenes, steady sliding spreads out of the deep zone of frictional stability and keeps expanding updip during the interseismic period. Aseismic slip episodes (ASEs) develop spontaneously within the region of steady sliding and repeat quasi-periodically. When steady sliding has spread beyond a certain critical length (the nucleation length) above the zone of frictional stability, one of the ASEs undergoes rapid buildup and avalanches into high-speed seismic sliding. When a step-like stress change intervenes, ASEs of larger amplitudes arise and evolve similarly to their spontaneous counterparts until one of them avalanches into an earthquake. If the stress change arrives not too early nor too late in the seismic cycle, the basic picture is as follows: delaying the stress step, be it positive or negative, delays the timing of the ASE sequence and thereby postpones the next earthquake. When the stress step is delayed to more than a certain extent, however, an earlier ASE gets to evolve into an earthquake, advancing its time discontinuously. Only in the final stage of a seismic cycle does a positive stress step systematically advance the next earthquake and a negative stress step systematically delay it.