The 2008 M_w7.9 Wenchuan earthquake ruptured northwest-dipping imbricate oblique reverse faults along the Longmenshan thrust belt at the eastern margin of the Tibetan Plateau, and developed one of the most complex coseismic rupture patterns for reverse faulting events ever reported in intraplate settings. To evaluate to what extent complex fault geometry and heterogeneities in initial stress can explain the characteristics of coseismic observations, we simulate spontaneous dynamic rupture propagation governed by slip-weakening friction law on the geometrically complex multifault system loaded by heterogeneous stress. Our model reproduces many observed features including the multifault ruptures, locations of the maximum slip, Interferometric Synthetic Aperture Radar observations, source time functions and peak ground velocities. Our results suggest that the maximum horizontal principal stress in the northern part of Beichuan Fault (BFC) is rotated approximately counterclockwise compared to that in the southern part of BFC, yet this rotation is not sufficient to produce a supershear rupture. We infer that the fault core zone in the southwestern Beichuan Fault (BCF) may have been more severely damaged than the northeastern counterpart, which provides an explanation that the rupture in the northern BCF propagates faster than in the southern portion. Besides, we find that Coulomb failure stress changes on Wenchuan-Maoxian Fault (WMF) may be counteracted by the aftershock slips of the Lixian Fault, which suggests Wenchuan earthquake could not significantly push the WMF closer to failure.

中文翻译：

---

2008 年 7.9 汶川地震的动态破裂模拟：异质初始应力和复杂多断层几何的意义

2008年的中号_{w ^}7.9 汶川地震沿青藏高原东缘龙门山逆冲带断裂了西北倾覆瓦状斜逆断层，形成了板内逆断层事件最复杂的同震破裂模式之一。为了评估复杂断层几何形状和初始应力的非均质性在多大程度上可以解释同震观测的特征，我们模拟了由非均质应力加载的几何复杂多断层系统上的滑动减弱摩擦定律控制的自发动态破裂传播。我们的模型再现了许多观测到的特征，包括多断层破裂、最大滑动位置、干涉合成孔径雷达观测、源时间函数和峰值地速。与 BFC 南部相比逆时针旋转，但这种旋转不足以产生超剪切破裂。我们推断，北川断裂（BCF）西南部的断层核心带可能比东北部的断层核心区受到更严重的破坏，这就解释了 BCF 北部的破裂传播速度比南部快。此外，我们发现汶川-茂县断层（WMF）的库仑破坏应力变化可能被溧县断层的余震滑动抵消，这表明汶川地震不能显着推动WMF更接近破坏。