FAULT STEPS AND THE DYNAMIC RUPTURE PROCESS - 2-D NUMERICAL SIMULATIONS OF A SPONTANEOUSLY PROPAGATING SHEAR FRACTURE
FAULT STEPS AND THE DYNAMIC RUPTURE PROCESS - 2-D NUMERICAL SIMULATIONS OF A SPONTANEOUSLY PROPAGATING SHEAR FRACTURE
复制标题
DOI：
10.1029/91gl01061
复制
发表时间：
1991-05-01
影响因子：
5.2
通讯作者：
DAY, SM
中科院分区：
文献类型：
--
作者：
HARRIS, RA;ARCHULETA, RJ;DAY, SM
断层阶跃可能控制了1966年帕克菲尔德、1968年博雷戈山、1979年帝国山谷、1979年狼湖和1987年迷信山地震的规模。本计画探讨断层阶跃对动态破裂过程之影响。我们用有限差分法模拟了二维自发破裂的传播过程。我们采用滑动弱化断裂准则作为破裂传播的条件，并研究一个平面上的破裂如何引发平行断层面上的破裂。两个平行断层面的几何形状允许0.5至10.0 km的跨越宽度和-5至5 km的重叠。我们的研究结果表明，自发破裂的第一个故障段继续传播到第二个故障段的一系列几何形状的压缩和扩张故障步骤。压缩和扩张的情况之间的一个主要区别是，扩张步骤需要一个较长的时间延迟之间的破裂前到达第一个故障段的结束和启动破裂的第二段。因此，我们的动力学研究表明，一个压缩步骤将迅速跳跃，而扩张步骤将导致一个时间延迟，导致较低的视破裂速度。我们还发现，破裂能够跨越一个比挤压阶更宽的扩张阶。
Fault steps may have controlled the sizes of the 1966 Parkfield, 1968 Borrego Mountain, 1979 Imperial Valley, 1979 Coyote Lake and the 1987 Superstition Hills earthquakes. This project investigates the effect of fault steps of various geometries on the dynamic rupture process. We have used a finite difference code to simulate spontaneous rupture propagation in two dimensions. We employ a slip-weakening fracture criterion as the condition for rupture propagation and examine how rupture on one plane initiates rupture on parallel fault planes. The geometry of the two parallel fault planes allows for stepover widths of 0.5 to 10.0 km and overlaps of -5 to 5 km. Our results demonstrate that the spontaneous rupture on the first fault segment continues to propagate onto the second fault segment for a range of geometries for both compressional and dilational fault steps. A major difference between the compressional and dilational cases is that a dilational step requires a longer time delay between the rupture front reaching the end of the first fault segment and initiating rupture on the second segment. Therefore our dynamic study implies that a compressional step will be jumped quickly, whereas a dilational step will cause a time delay leading to a lower apparent rupture velocity. We also find that the rupture is capable of jumping a wider dilational step than compressional step.