Pulse-Like Rupture Induced by Three-Dimensional Fault Zone Flower Structures
Pulse-Like Rupture Induced by Three-Dimensional Fault Zone Flower Structures
复制标题
三维断层带花状结构诱发的脉冲式破裂
DOI：
10.1007/s00024-014-0881-0
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发表时间：
2013
影响因子：
2
通讯作者：
J. Ampuero
中科院分区：
文献类型：
--
作者：
C. Pelties;Yihe Huang;J. Ampuero
断层通常嵌入由物质损坏引起的低速断层带（LVFZ）中。先前的二维动态破裂模拟（Huang和Ampuero，2011；Huang等，2014）表明，如果LVFZ和围岩之间的波速对比足够强，破裂可以表现为脉冲，即局部滑移持续时间（上升时间）远短于整个破裂持续时间。局部滑动阻止（愈合）是由 LVFZ-乡村岩石界面反射的波产生的。这种效应对于大范围的断层带宽度、缺乏摩擦愈合、初始应力条件的变化、衰减和断层外塑性来说是稳健的。这些数值研究涵盖了断层平行断层带结构的二维问题。在这里，我们将之前的工作扩展到更典型的自然断层带的 3D 和几何形状，包括具有与深度相关的速度和厚度的花结构以及有限的断层带深度范围等复杂性。这项研究需要高分辨率和灵活的网格生成，这可以通过具有非结构化四面体单元离散化的高阶精确任意高阶导数不连续伽辽金方法来实现（Peltieset al., 2012）。我们表明，由 LVFZ 反射的波引起的愈合机制在这种三维断层带结构中也能有效地发挥作用，此外，当破裂到达地表时产生的卸载波会引起一种新的愈合机制。第一种机制导致由 LVFZ 宽度与波速比控制的非常短的上升时间。第二种机制通常导致更长、深度增加的上升时间，也以 LVFZ 的存在为条件，并且持续存在于 LVFZ 底部以下的某个深度。我们的模拟表明，这两种机制产生的滑移脉冲对于 LVFZ 的深度范围和震源位置来说是稳健的。对于震源位于 LVFZ 内的事件，第一种修复机制占主导地位。如果震源比浅 LVFZ 更深，则第二个占主导地位。这些结果表明，上升时间的深度依赖性可能有助于限制 LVFZ 的深度范围。我们还表明，在速度均匀降低的花状 LVFZ 中，破裂可以自发停止，但如果速度降低与深度相关，则破裂会以滑移脉冲的形式继续传播。
Faults are often embedded in low-velocity fault zones (LVFZ) caused by material damage. Previous 2D dynamic rupture simulations (Huang and Ampuero, 2011; Huang et al., 2014) showed that if the wave velocity contrast between the LVFZ and the country rock is strong enough, ruptures can behave as pulses, i.e. with local slip duration (rise time) much shorter than whole rupture duration. Local slip arrest (healing) is generated by waves reflected from the LVFZ–country rock interface. This effect is robust against a wide range of fault zone widths, absence of frictional healing, variation of initial stress conditions, attenuation, and off-fault plasticity. These numerical studies covered two-dimensional problems with fault-parallel fault zone structures. Here, we extend previous work to 3D and geometries that are more typical of natural fault zones, including complexities such as flower structures with depth-dependent velocity and thickness, and limited fault zone depth extent. This investigation requires high resolution and flexible mesh generation, which are enabled here by the high-order accurate arbitrary high-order derivatives discontinuous Galerkin method with an unstructured tetrahedral element discretization (Peltieset al., 2012). We show that the healing mechanism induced by waves reflected in the LVFZ also operates efficiently in such three-dimensional fault zone structures and that, in addition, a new healing mechanism is induced by unloading waves generated when the rupture reaches the surface. The first mechanism leads to very short rise time controlled by the LVFZ width to wave speed ratio. The second mechanism leads to generally longer, depth-increasing rise times, is also conditioned by the existence of an LVFZ, and persists at some depth below the bottom of the LVFZ. Our simulations show that the generation of slip pulses by these two mechanisms is robust to the depth extent of the LVFZ and to the position of the hypocenter. The first healing mechanism is dominant for events with hypocenter inside the LVFZ. The second one is dominant if the hypocenter is deeper than a shallow LVFZ. These results suggest that the depth-dependence of rise time might help constrain the depth extent of the LVFZ. We also show that ruptures can spontaneously stop in flower-like LVFZs with uniform velocity reduction, but continue propagating as slip pulses if velocity reduction is depth-dependent.
验证复杂动态破裂问题的 ADER-DG 方法
影响因子：
5.1
作者：
C. Pelties;A.-A. Gabriel;J.-P. Ampuero
通讯作者：
J.-P. Ampuero