The Leech River fault (LRF) zone located on southern Vancouver Island is a major regional seismic source. We investigate potential interactions between earthquake ruptures on the LRF and the neighboring Southern Whidbey Island fault (SWIF), which can be interpreted as a step‐over fault system. Using a linear slip‐weakening frictional law, we perform 3‐D finite‐element simulations to study rupture jumping scenarios from the LRF (source fault) to the SWIF (receiver fault), focusing on the influences of the offset distance, fault initial stress level, and fault burial depth. We find a smaller offset distance, a higher initial stress level on either fault, or a shallower fault burial depth will promote rupture jumping. Jumping scenarios can be interpreted as the response of the receiver fault to stress perturbations radiated from the source fault rupture. We demonstrate that the final rupture jumping scenario depends on various parameters, which can be collectively quantified by two keystone variables, the time‐averaged over‐stressed zone (where shear stress exceeds static frictional strength on the receiver fault) size and the receiver fault initial stress level. Specifically, a smaller offset distance, a higher initial shear stress level, or a shallower burial depth will lead to a larger . The seismic moment on the receiver fault increases with increasing . When reaches the threshold dependent on the receiver fault initial stress level, the rupture becomes breakaway.

中文翻译：

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跨步断层系统的地震破裂：南温哥华岛水ch河断层的探索性数值研究

位于温哥华岛南部的水ch河断裂带（LRF）是主要的区域地震源。我们调查了LRF和邻近的南部惠德比岛断层（SWIF）上的地震破裂之间的潜在相互作用，这可以解释为跨步断层系统。使用线性滑弱摩擦定律，我们执行3D有限元模拟，研究从LRF（源断层）到SWIF（接收器断层）的破裂跳跃场景，重点是偏移距离，断层初始应力的影响级别和断层埋藏深度。我们发现较小的偏移距离，较高的断层初始应力水平或较浅的断层埋藏深度将促进破裂跳跃。跳跃的情况可以解释为接收器断层对源断层放射出的应力扰动的响应。我们证明了最终的破裂跳跃场景取决于各种参数，这些参数可以通过两个关键变量共同量化：时间平均过应力区域（在该区域，剪应力超过接收器断层上的静态摩擦强度）以及接收器故障的初始应力水平。具体而言，较小的偏移距离，较高的初始剪切应力水平或较浅的埋葬深度将导致较大的。接收机断层上的地震矩随着增大而增大。当达到取决于接收器故障的初始应力水平的阈值时，破裂会破裂。