Why Do Aftershocks Occur Within the Rupture Area of a Large Earthquake?
Why Do Aftershocks Occur Within the Rupture Area of a Large Earthquake?
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DOI：
10.1029/2018gl077843
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发表时间：
2018-05
影响因子：
5.2
通讯作者：
S. Yabe;S. Ide
中科院分区：
文献类型：
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作者：
S. Yabe;S. Ide
主震-余震序列是地震成因的基本特征之一，但余震产生的物理机制仍然知之甚少。简单地解释余震是由主震应变能的重新分布引起的并不总是适用的，特别是对于主震滑动区内的余震，那里的应变能被释放。在这里，我们表明，余震的成因可以使用一个非均匀的断层系统建模。我们进行了准动态数值模拟的故障破裂周期的有限故障率和状态依赖的摩擦定律。当摩擦不均匀性沿断层沿着发生显著变化时，在主震破裂区周围和内部可观察到余震。另一方面，当摩擦不均匀性的沿着断层变化很小时，就不会产生余震，这与重复地震中观察到的余震缺乏相似。
The mainshock‐aftershock sequence is one of the fundamental characteristics of seismogenesis, yet the physical mechanism of aftershock generation remains poorly understood. The simple explanation that aftershocks are caused by the mainshock's redistribution of strain energy is not always applicable, especially for aftershocks within the mainshock slip area, where strain energy is released. Here we show that the genesis of aftershocks can be modeled using a frictionally heterogeneous fault system. We conducted quasi‐dynamic numerical simulations of fault rupture cycles on a finite fault governed by a rate‐ and state‐dependent friction law. Aftershocks are observed around and within the mainshock rupture area when the frictional heterogeneity varies significantly along the fault. On the other hand, aftershocks are not produced when along‐fault variations in the frictional heterogeneity are small, which mimics the observed lack of aftershocks for repeating earthquakes.