Spatiotemporal properties of Sub-Rayleigh and supershear rupture velocity fields: Theory and experiments
Spatiotemporal properties of Sub-Rayleigh and supershear rupture velocity fields: Theory and experiments
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DOI：
10.1016/j.jmps.2016.02.031
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发表时间：
2016-08
影响因子：
5.3
通讯作者：
M. Mello;H. Bhat;A. Rosakis
中科院分区：
文献类型：
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作者：
M. Mello;H. Bhat;A. Rosakis
通过一系列室内地震实验，研究了亚瑞利和超剪切破裂的基本时空场特性和质点速度波形特征。我们呼吁动态破裂理论提取和突出以前未被注意的方面和结果，这是我们的新实验直接相关。奇异和非奇异的解决方案推导出的运动学关系被应用到分析和解释在这些实验中观察到的各种功能。在实验室实验中获得的颗粒速度记录和理论推导的合成颗粒速度波形剖面之间表现出很强的对应关系。预测的时间分布，粒子运动的意义，和振幅衰减特性的子瑞利和超剪切粒子速度波形进行了实验验证。在一组特定的超剪切破裂实验中，断层正常（FN）和断层平行（FP）的速度波形同时记录在固定的，离断层的字段点作为剪切马赫前扫过这些位置。在一个稳定的超剪切破裂速度范围内收集的粒子速度记录证实了由剪切马赫阵面传播的FP（δ u 1 s今）和FN（δ u 2 s今）速度跃变之间的标度关系δ u今1 s/δ u今2 s = Vr 2/Cs 2 − 1 = β s。其他的实验结果包括详细的断裂速度测量的亚瑞利和超剪切断裂和观察的超剪切子裂纹与消失的剪切马赫前。以前未被赞赏的粒子速度场分量之间的标度关系，归因于湍流和剪切波，也开发和实验验证。特别是，FP速度跳跃δ u 1 s至今（x 1，x 2），在离摩擦断层面非常近的场点处测量的滑动速度δ u 1（x 1，0+）服从速度相关的标度关系：δ u今1 s/δ u今1 += 1 − 2 C s 2 V r 2，这是从非奇异的稳态速度场解中收集的。
Fundamental spatiotemporal field properties and particle velocity waveform signatures of sub-Rayleigh and supershear ruptures were experimentally investigated through a series of laboratory earthquake experiments. We appeal to dynamic rupture theory to extract and highlight previously unnoticed aspects and results, which are of direct relevance to our new experiments. Kinematic relationships derived from both singular and non-singular solutions are applied to analyze and interpret various features observed in these experiments. A strong correspondence is demonstrated between particle velocity records obtained in lab experiments and synthetic particle velocity waveform profiles derived from theory. Predicted temporal profiles, sense of particle motion, and amplitude decay properties of sub-Rayleigh and supershear particle velocity waveforms are experimentally verified. In a particular set of supershear rupture experiments, the fault-normal (FN) and fault-parallel (FP) velocity waveforms were simultaneously recorded at fixed, off-fault field points as a shear Mach front swept these locations. Particle velocity records collected over a broad range of stable supershear rupture speeds validate the predicted scaling relationship δ u ̇ 1 s/δ u ̇ 2 s= V r 2/C s 2− 1= β s, between the FP (δ u 1 s ̇) and the FN (δ u 2 s ̇) velocity jumps propagated by a shear Mach front. Additional experimental findings include detailed rupture speed measurements of sub-Rayleigh and supershear ruptures and the observation of a supershear daughter crack with vanishing shear Mach front. Previously unappreciated scaling relations between particle velocity field components, attributed to dilatational and shear waves, are also developed and experimentally verified. In particular, the FP velocity jump δ u 1 s ̇ (x 1, x 2) propagated by the shear Mach front, and the sliding speed δ u ̇ 1 (x 1, 0+), measured at a field point positioned extremely close to the frictional fault plane, are shown to obey a speed-dependent scaling relationship given by δ u ̇ 1 s/δ u ̇ 1+= 1− 2 C s 2 V r 2, which was gleaned from a non-singular, steady state velocity field solution.