The effect of thermal pressurization on dynamic fault branching
The effect of thermal pressurization on dynamic fault branching
复制标题
热加压对动态断层分支的影响
DOI：
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发表时间：
2014
期刊：
影响因子：
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通讯作者：
R. Madariaga
中科院分区：
文献类型：
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作者：
Y. Urata;S. Hok;E. Fukuyama;R. Madariaga
总结 我们通过数值研究热加压（TP）对动态破裂传播过程中断层分支行为的影响，这种情况可能发生在俯冲界面的大地震期间。我们考虑无限介质中的二维 II 型（面内）破裂，该破裂沿着平面主断层自发传播并遇到与预先存在的分支断层的交叉点。断层系统受到均匀的外应力。我们采用 Kame 等人使用的值。我们使用二维边界积分方程方法和具有库仑破坏准则的弱滑摩擦定律，允许有效法向应力随着 TP 导致的孔隙压力变化而变化。我们发现，当主断层倾角较小时，TP 可以改变破裂传播路径。正如 Kame 等人所述，当 TP 对任一断层均不起作用时，破裂传播路径取决于分支角度。然而，动态破裂过程更多地受TP控制，而不是受分支角控制。当TP仅作用于主断层时，破裂沿主断层扩展。当 TP 对两个故障都有效时，它会沿着分支传播。最后，我们考虑了分支断层系统上方存在自由面的情况。在这种情况下，除了主断层上的TP之外，由于自由表面和分支断层之间的相互作用，破裂可以沿着两个断层传播。
S U M M A R Y We numerically investigate the effect of thermal pressurization (TP) on fault branch behaviour during dynamic rupture propagation, a situation likely to occur during large earthquakes at subduction interfaces. We consider a 2-D mode II (in-plane) rupture in an infinite medium that propagates spontaneously along a planar main fault and encounters an intersection with a pre-existing branching fault. The fault system is subjected to uniform external stresses. We adopt the values used by Kame et al. We use the 2-D boundary integral equation method and the slip-weakening friction law with a Coulomb failure criterion, allowing the effective normal stress to vary as pore pressure changes due to TP. We reveal that TP can alter rupture propagation paths when the dip angle of the main fault is small. The rupture propagation paths depend on the branching angle when TP is not in effect on either of the faults, as described by Kame et al. However, the dynamic rupture processes are controlled more by TP than by the branching angle. When TP is in effect on the main fault only, the rupture propagates along the main fault. It propagates along the branch when TP is in effect on both faults. Finally, we considered the case where there is a free surface above the branch fault system. In this case, the rupture can propagate along both faults because of interaction between the free surface and the branch fault, in addition to TP on the main fault.