Within the fore-arc of the Cascadia Subduction Zone, there are significant along-strike differences in the orientation of splay faults, sediment consolidation, and fault roughness. Here we use dynamic rupture simulations of megathrust earthquakes on different realizations of a fault system that incorporate fore-arc properties representative of offshore Oregon and Washington to estimate how splay faults may behave in future megathrust earthquakes in Cascadia. While splay faults were activated in all of our simulations, splay orientation is a primary control on slip amplitude. Seaward vergent faults accommodate significant amounts of slip resulting in large seafloor uplift and significantly larger tsunami amplitudes. For example, our median tsunami heights including splay faults are about a factor of two larger than those that did not include splay fault deformation. We suggest that there is an urgent need to revisit existing approaches to tsunami hazard assessment in Cascadia to include the influence of splay faults.

中文翻译：

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前弧变形对卡斯卡迪亚俯冲带浅层地震破裂行为的影响

在卡斯卡迪亚俯冲带前弧内，张开断层的走向、沉积物固结和断层粗糙度存在显着的沿走差异。在这里，我们在断层系统的不同实现上使用巨型逆向地震的动态破裂模拟，该系统结合了代表俄勒冈州和华盛顿近海的前弧特性，以估计张开断层在未来卡斯卡迪亚的巨型逆向地震中的表现。虽然在我们的所有模拟中都激活了张开断层，但张开方向是对滑动幅度的主要控制。向海辐合断层可容纳大量滑动，导致海底大隆起和海啸振幅显着增大。例如，我们包括张开断层在内的海啸高度中值比不包括张开断层变形的海啸高度高约两倍。我们建议迫切需要重新审视现有的卡斯卡迪亚海啸灾害评估方法，以包括张开断层的影响。