Detailed imaging of accretionary wedges reveals splay fault networks that could pose a significant tsunami hazard. However, the dynamics of multiple splay fault activation during megathrust earthquakes and the consequent effects on tsunami generation are not well understood. We use a 2-D dynamic rupture model with complex topo-bathymetry and six curved splay fault geometries constrained from realistic tectonic loading modeled by a geodynamic seismic cycle model with consistent initial stress and strength conditions. We find that all splay faults rupture coseismically. While the largest splay fault slips due to a complex rupture branching process from the megathrust, all other splay faults are activated either top down or bottom up by dynamic stress transfer induced by trapped seismic waves. We ascribe these differences to local non-optimal fault orientations and variable along-dip strength excess. Generally, rupture on splay faults is facilitated by their favorable stress orientations and low strength excess as a result of high pore-fluid pressures. The ensuing tsunami modeled with non-linear 1-D shallow water equations consists of one high-amplitude crest related to rupture on the longest splay fault and a second broader wave packet resulting from slip on the other faults. This results in two episodes of flooding and a larger run-up distance than the single long-wavelength (300 km) tsunami sourced by the megathrust-only rupture. Since splay fault activation is determined by both variable stress and strength conditions and dynamic activation, considering both tectonic and earthquake processes is relevant for understanding tsunamigenesis.

中文翻译：

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多张断层地震破裂及其对海啸的影响

增生楔的详细成像揭示了可能造成重大海啸危险的张开断层网络。然而，大逆冲地震期间多张断层激活的动力学及其对海啸产生的影响尚不清楚。我们使用具有复杂地形测深的二维动态破裂模型和六个弯曲的张开断层几何形状，这些几何形状受现实构造载荷的约束，该模型由具有一致初始应力和强度条件的地球动力学地震循环模型建模。我们发现所有的张开断层都是同震破裂的。虽然最大的张开断层由于来自巨型逆冲断层的复杂破裂分支过程而发生滑动，但所有其他张开断层都是由被捕获的地震波引起的动态应力转移自上而下或自下而上激活的。我们将这些差异归因于局部非最佳断层方向和可变的沿倾角强度过剩。通常，由于高孔隙流体压力导致的有利应力方向和低强度过剩，促进了张开断层的破裂。用非线性一维浅水方程模拟的随后发生的海啸由一个与最长的张开断层上的破裂相关的高振幅波峰和另一个由其他断层滑动产生的更宽的波包组成。与仅由巨型逆冲断裂引发的单次长波长（300 公里）海啸相比，这导致了两次洪水事件和更大的上升距离。由于张开断层的激活是由可变应力和强度条件以及动态激活决定的，