Numerical simulations of earthquake triggering by dynamic and static stress changes based on a revised friction law
Numerical simulations of earthquake triggering by dynamic and static stress changes based on a revised friction law
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基于修正摩擦定律的动态和静态应力变化引发地震的数值模拟
DOI：
10.1029/2017jb014781
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发表时间：
2018
影响因子：
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通讯作者：
Shingo Yoshida
中科院分区：
文献类型：
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作者：
Yoshida Shingo;Maeda Takuto;Kato Naoyuki;島田 誠一;Shingo Yoshida
我们使用Nagata et al.（2012，https：//doi.org/10.1029/2011JB008818）修订的速率和状态相关摩擦定律，假设圆形粗糙体，进行了地震触发的数值模拟。对于地震反复发生的情况，我们采用动态正弦应力扰动。扰动停止后，应力扰动使滑移速度增大，滑移减弱了摩擦强度。这将导致动态地震触发某些扰动幅度。获得了以下结果。(1)长持续时间的动态扰动具有高触发电位，而没有显著的频率依赖性，因为电位主要由扰动引起的总位移决定。(2)当除了动态扰动之外还施加静态应力跃变时，它们对触发电位的组合效应不能通过简单地将施加的应力幅度相加来估计。下限可以通过对由于每个单独的扰动而引起的速度变化的均方根求和来找到。此外，需要一个非线性效应来解释模拟结果。(3)我们评估的等效静态应力跳，结果在一个触发电位大致相同的情况下的动态应力扰动。(4)即使静态应力变化是负的，大的动态应力扰动也能引发地震。(5)当应力扰动作用于稳定滑动的贴片时，在一定条件下会发生动态触发。
We conducted numerical simulations of earthquake triggering by assuming a circular asperity using a rate‐ and state‐dependent friction law revised by Nagata et al. (2012, https://doi.org/10.1029/2011JB008818). For a situation in which earthquakes occurred repeatedly, we applied dynamic sinusoidal stress perturbation. The stress perturbation caused an increase in slip velocity after the cessation of perturbation, and the resultant slip weakened the frictional strength. This leads to dynamic earthquake triggering for certain perturbation amplitudes. The following results were obtained. (1) Dynamic perturbations of long durations have high triggering potentials, whereas there is no significant frequency dependence because the potential is mainly determined by the total displacement due to the perturbation. (2) When a static stress jump is applied in addition to a dynamic perturbation, their combined effect on the triggering potential cannot be estimated by simply summing the applied stress amplitudes. A lower bound can be found by summing the logarithms of the velocity changes due to each individual perturbation. In addition, a nonlinear effect is required to explain the simulation results. (3) We evaluate the equivalent static stress jump that results in a triggering potential approximately the same as in the case of dynamic stress perturbation. (4) Even if the static stress change is negative, large dynamic stress perturbations can trigger earthquakes. (5) When stress perturbations are applied to stably sliding patches, dynamic triggering can occur under certain conditions.