What can surface slip distributions tell us about fault connectivity at depth?

Fault systems with stepovers and gaps along strike are ubiquitous in nature, and many modern earthquakes (e.g. 1992 Landers, 1999 Hector Mine, 2016 Kaikoura, and 2019 Ridgecrest) have shown that ruptures can readily propagate across some disconnections, while being halted by others. It is quite possible, however, that many faults that appear discontinuous at the surface are in fact connected at depth, facilitating through-going rupture, and potentially increasing earthquake size. The present work explores whether the mapped surface slip in an earthquake is indicative of the connectivity of the fault system at depth. If there is a signal of subsurface connectivity in the surface slip pattern, then the connectivity of the system could potentially be inferred. Through 3D Dynamic rupture modeling of faults with along-strike gaps of various depths, I explore whether the amplitude or the spatial distribution of slip after an earthquake could be used to diagnose fault connectivity at depth. I ...自然界中，沿走向存在阶区与间隙的断裂系统广泛发育。诸多现代地震（例如1992年兰德斯地震、1999年赫克托矿地震、2016年凯库拉地震与2019年里奇克莱斯特地震）的震例表明，破裂可顺利穿越部分不连续断裂段，却会被其余不连续段阻断。然而，诸多地表看似不连续的断裂，实则在深部相互连通，这既可为贯通式破裂提供条件，也可能增大地震震级。本研究旨在探讨地震中经编录的地表滑动分布，能否反映断裂系统在深部的连通状态。若地表滑动分布中存在表征深部连通性的信号，则可通过该信号反推断裂系统的连通性。本研究通过对沿走向存在不同深度间隙的断裂开展三维动态破裂模拟，探讨能否利用地震后滑动的振幅与空间分布特征，判断断裂在深部的连通性。本文……