Impact of the receiver fault distribution on aftershock activity
Impact of the receiver fault distribution on aftershock activity
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DOI：
10.1029/2008jb006224
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发表时间：
2010-05
影响因子：
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通讯作者：
S. Hainzl;G. Zöller;Rongjiang Wang
中科院分区：
文献类型：
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作者：
S. Hainzl;G. Zöller;Rongjiang Wang
[1] 余震模型通常基于忽略物理机制的纯粹经验关系，或者基于预定义接收器断层方向上应力变化的确定性计算。在这里，我们研究了在基于静态库仑应力变化的模型中考虑更现实的断层系统的效果。为此，我们使用弹性半空间应力相互作用、速率和状态相关的摩擦地震成核以及具有异质（分形）滑移分布的扩展破裂来进行地震模拟。我们发现，考虑多个接收断层方向上的地震成核并不影响时间大森型余震衰减的形状，但显着改变了预测的空间模式和触发事件的总数。所谓的活动减少的应力阴影几乎消失，并且活动随着距主震破裂距离的增加而持续衰减。如果存在多个接收器断层面，则总余震生产力几乎与假设的背景率无关，会显着增加。对 1992 年加利福尼亚州兰德斯 M7.3 余震序列的应用表明，与观测到的直接触发余震的位置和总生产力有很好的一致性。
[1] Aftershock models are usually based either on purely empirical relations ignoring the physical mechanism or on deterministic calculations of stress changes on a predefined receiver fault orientation. Here we investigate the effect of considering more realistic fault systems in models based on static Coulomb stress changes. For that purpose, we perform earthquake simulations with elastic half-space stress interactions, rate-and-state dependent frictional earthquake nucleation, and extended ruptures with heterogeneous (fractal) slip distributions. We find that the consideration of earthquake nucleation on multiple receiver fault orientations does not influence the shape of the temporal Omori-type aftershock decay, but changes significantly the predicted spatial patterns and the total number of triggered events. So-called stress shadows with decreased activity almost vanish, and activation decays continuously with increasing distance from the main shock rupture. The total aftershock productivity, which is shown to be almost independent of the assumed background rate, increases significantly if multiple receiver fault planes exist. The application to the 1992 M7.3 Landers, California, aftershock sequence indicates a good agreement with the locations and the total productivity of the observed directly triggered aftershocks.