3D Finite-Element Modeling of Dynamic Rupture and Aseismic Slip over Earthquake Cycles on Geometrically Complex Faults
3D Finite-Element Modeling of Dynamic Rupture and Aseismic Slip over Earthquake Cycles on Geometrically Complex Faults
复制标题
几何复杂断层地震周期动态破裂和抗震滑移的 3D 有限元建模
DOI：
10.1785/0120200047
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发表时间：
2020
影响因子：
3
通讯作者：
Dunyu Liu
中科院分区：
文献类型：
--
作者：
B. Luo;B. Duan;Dunyu Liu
我们开发了一种新的动态地震模拟器，以数值模拟地震周期上由速率和状态相关摩擦控制的几何复杂断层系统的自发破裂和地震滑动。该方法基于动态有限元法EQdyna，可直接用于三维自发破裂模拟。我们在EQdyna中应用了自适应动态松弛技术和可变时间步进方案来模拟地震周期的准静态过程，包括震后、震间和成核过程。因此，一个地震周期的动态过程和准静态过程在一个有限元框架中建模。在一个垂直走滑断层上的试验验证了动态模拟器的正确性。将不同倾角逆冲断层与垂直断层相比较，将其作为几何复杂断裂的最简单破对称情况，研究了倾角逆冲断层几何形态对地震旋回行为的影响。研究发现，浅层倾斜逆冲断层在相同断裂区域的地震旋回上产生较大的地震滑动和较长的重复时间。此外，我们发现递推区间（和地震矩）与倾角的正弦函数之间存在经验线性标度关系。倾角依赖可能是由于自由面效应，因为对称性被打破。这些结果表明，俯冲带地震研究需要能够处理非垂直倾斜断层几何形状的动态地震模拟器。
We develop a new dynamic earthquake simulator to numerically simulate both spontaneous rupture and aseismic slip over earthquake cycles on geometrically complex fault systems governed by rate- and state-dependent friction. The method is based on the dynamic finite-element method (FEM) EQdyna, which is directly used in the simulator for modeling 3D spontaneous rupture. We apply an adaptive dynamic relaxation technique and a variable time stepping scheme to EQdyna to model the quasi-static processes of an earthquake cycle, including the postseismic, interseismic, and nucleation processes. Therefore, the dynamic and quasi-static processes of an earthquake cycle are modeled in one FEM framework. Tests on a vertical strike-slip fault verify the correctness of the dynamic simulator. We apply the simulator to thrust faults with various dipping angles, which can be considered as the simplest case of geometrically complex faults by breaking symmetry, compared with vertical faults, to examine effects of dipping fault geometry on earthquake cycle behaviors. We find that shallower dipping thrust faults produce larger seismic slip and longer recurrence time over earthquake cycles with the same rupture area. In addition, we find an empirically linear scaling relation between the recurrence interval (and the seismic moment) and the sinusoidal function of the dip angle. The dip-angle dependence is likely due to the free-surface effect, because of broken symmetry. These results suggest dynamic earthquake simulators that can handle nonvertical dipping fault geometry are needed for subduction-zone earthquake studies.