Observation-constrained multicycle dynamic models of the Pingding Shan earthquake gate along the Altyn Tagh Fault
Observation-constrained multicycle dynamic models of the Pingding Shan earthquake gate along the Altyn Tagh Fault
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阿尔金断裂带平顶山地震门观测约束多周期动力模型
DOI：
10.1016/j.tecto.2021.228948
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发表时间：
2021-09
期刊：
影响因子：
2.9
通讯作者：
Jing Liu-Zeng
中科院分区：
文献类型：
--
作者：
Liu Dunyu;Duan Benchun;Prush Veronica B.;Oskin Michael E.;Jing Liu-Zeng
地震门是断层几何形状的复杂性，常见于天然断层系统中，有条件地阻止地震破裂。本研究以阿尔金断裂带中段沿着平顶山地震闸门的多尺度动力学模拟为中心。地震门包括三个几何复杂性：一个突出的约束弯曲，一个4公里宽的台阶向东，和一个释放弯曲向西。我们使用二维有限元方法模拟地震同震自发破裂与地震断层应力演化计算的粘弹性解析解。古地震记录和长期滑动率被用来约束模型。我们发现，断层几何相关的非均匀应力积累在地震周期产生复杂的破裂模式，并帮助解释地震复发间隔揭示的古地震记录。三个最重要的贡献，非均匀应力来自动态断裂通过断层几何复杂性，断层走向依赖的构造加载和松弛，应力历史从过去的地震。在平顶山地震闸门中，释放步距比约束弯曲更能有效地阻止破裂。约束弯曲和释放步距的共同作用使平顶山地震闸门成为350 km模型跨越断裂的非常有效的屏障。最佳拟合模型产生一个低复发间隔4.6 kyrs为350公里长的破裂，穿插更频繁的破裂仅限于个别故障段。较低的静摩擦力往往会降低地震闸门阻止破裂的有效性。局部故障几何复杂性，以及快速的能量释放和重新加强的摩擦力在动态断裂有助于解释0.66重现间隔的变异系数（COV）记录在铜矿古地震沟网站上的Xorxoli段。这项研究提供了一种方法，考虑到过去的地震和断层几何形状的影响，适用于单次动态破裂模拟的非均匀初始应力。
Earthquake gates are fault geometric complexities, common in natural fault systems, that conditionally impede earthquake ruptures. This study centers on modeling of multicycle dynamics of the Pingding Shan earthquake gate along the central Altyn Tagh Fault in northwest China. The earthquake gate includes three geometric complexities: a prominent restraining bend, a 4-km wide stepover to the east, and a releasing bend to the west. We use a 2D finite element method to simulate coseismic spontaneous ruptures with interseismic fault stress evolutions computed by an analytic viscoelastic solution. Paleoseismic records and long-term slip-rates are used to constrain the models. We find that fault-geometry-related heterogenous stresses accumulated over earthquake cycles yield complex rupture patterns and help explain earthquake recurrence intervals revealed by paleoseismic records. The three most important contributions to the heterogeneous stresses come from dynamic ruptures passing fault geometric complexities, fault-strike-dependent tectonic loading and relaxation, and stress history from past earthquakes. In the Pingding Shan earthquake gate, the releasing stepover appears to impede ruptures more effectively than the restraining bend. The combined impact of the restraining bend and the releasing stepover makes the Pingding Shan earthquake gate a very effective barrier to 350-km model-spanning ruptures. The best-fit model yields a low recurrence interval of 4.6 kyrs for 350-km-long ruptures, interspersed with more frequent ruptures limited to individual fault segments. A lower static friction tends to reduce the effectiveness of the earthquake gate to impede ruptures. Local fault geometric complexities together with rapid energy release and restrengthening of friction during dynamic ruptures help explain the 0.66 recurrence interval coefficient of variation (COV) recorded at the Copper Mine paleoseismic trench site on the Xorxoli segment. This study provides a method for applying heterogenous initial stresses for single-event dynamic rupture simulations that consider the effect of past earthquakes and fault geometry.
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影响因子：
5.2
作者：
A. Elliott;M. Oskin;J. Liu-zeng;Y. Shao
通讯作者：
A. Elliott;M. Oskin;J. Liu-zeng;Y. Shao
影响因子：
64.8
作者：
Di Toro, G;Goldsby, DL;Tullis, TE
通讯作者：
Tullis, TE
影响因子：
3
作者：
Dunham, Eric M.;Belanger, David;Kozdon, Jeremy E.
通讯作者：
Kozdon, Jeremy E.
影响因子：
5.8
作者：
A. Draut;P. Clift
通讯作者：
A. Draut;P. Clift
影响因子：
56.9
作者：
Bouchon, M;Vallée, M
通讯作者：
Vallée, M