Numerical simulation of spontaneous rupture processes on twonon-coplanar faults: the effect of geometry on fault interaction
Numerical simulation of spontaneous rupture processes on twonon-coplanar faults: the effect of geometry on fault interaction
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DOI：
10.1046/j.1365-246x.1998.00672.x
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发表时间：
1998-12
影响因子：
2.8
通讯作者：
Y. Kase;K. Kuge
中科院分区：
文献类型：
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作者：
Y. Kase;K. Kuge
对震源的总结分析表明，地震破裂过程复杂，破裂不是在单一平面上发生的。地震断层往往由多个次断层组成，破裂传播往往在断层走向改变的地方减速或终止。这些观测结果表明，断层几何形状，包括断层台阶和断层走向变化，对地震破裂的复杂性起着重要作用。本文计算了平面内问题中两个非共面断层的自发破裂过程，试图阐明断层几何学的作用。我们考虑两个简单的模型，其中两个断层要么平行，要么垂直。我们用差分法计算了断层上的自发破裂传播，并对结果进行了比较。在我们的模拟中，破裂最初在主断层上生长，主破裂产生的应力扰动然后触发次级断层上的破裂。主断层破裂的传播控制着均匀弹性介质中应力差的时空分布，决定了次级断层的破裂过程。两种模型对次级断层的破裂传播和终止有明显不同。当主断层破裂被截断且次断层位于主断层被截止端附近时，差异明显，当次断层与主断层平行时，破裂可以在次断层上向前扩展。然而，当次级断层垂直于主断层时，次级断层上的破裂要么不被触发，要么被触发后很快终止。破裂过程的这种变化意味着，断层相互作用，取决于几何，可以解释在断层走向不同的地方破裂的终止和变化。这说明了断层几何学在研究自发性动态破裂过程中的重要性。
SUMMARY Analyses of earthquake sources have revealed that the earthquake rupture process is complex and that the rupture does not occur on a single plane. Earthquake faults are often composed of several subfaults, and rupture propagation tends to decelerate or terminate at places where the fault strike changes. These observations imply that fault geometry, including fault steps and fault strike change, plays an important role in earthquake rupture complexity. In this paper, we calculate the spontaneous rupture processes of two non-coplanar faults in 2-D in-plane problems, attempting to clarify the eiect of fault geometry. We consider two simple modelsmodels in which two faults are either parallel or perpendicular to each other. We calculate spontaneous rupture propagation on the faults bya ¢nite diierence method, andwe then compare the results. In our simulations, rupture initially grows on the main fault, and stress perturbation from the main rupture then triggers rupture on the secondary fault. Propagation of the main-fault rupture controls a spatio^temporal pattern ofstress diierence in the uniform elastic medium, which determines the rupture process of the secondary fault. The rupture propagation and termination of the secondary fault are signi¢cantly diierent between the two models. The diierence is obvious when rupture of the main fault is arrested and the secondary fault is located near the arrested end of the main fault.When the secondary fault is parallel to the main fault, rupture can propagate ahead on the secondary fault. However, when the secondary fault is perpendicular to the main fault, rupture is either not triggered on the secondary fault, or soon terminates if triggered. This variation of the rupture process implies that fault interaction, depending on geometry, can explain the termination and change of rupture at places where the fault strike varies. This shows the importance of the fault geometry in studying spontaneous dynamic rupture processes.