Rupture Termination in Laboratory-Generated Earthquakes
Rupture Termination in Laboratory-Generated Earthquakes
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DOI：
10.1029/2018gl080492
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发表时间：
2018-12-16
影响因子：
5.2
通讯作者：
Kammer, David S.
中科院分区：
文献类型：
--
作者：
Ke, Chun-Yu;McLaskey, Gregory C.;Kammer, David S.
地震是一种动态破裂事件，它在地壳内部的断层上发生、传播和终止。了解破裂终止对于准确估计一个地区可能经历的最大震级地震至关重要。我们研究了M - 2.5地震序列的终止，破裂3米花岗岩实验室样品。在这个大尺度上，成核、传播和终止完全或部分地局限于岩石实验的样品-独特的观察。我们比较测量的终止位置估计从断裂力学为基础的模型，以量化的断裂能量的实验室地震，比较以及从小的自然地震的估计。我们的研究结果提供了一个数学框架，将微米尺度的摩擦参数与米尺度的地震力学联系起来，表明3米长的花岗岩板可以表现出与200毫米厚的玻璃状聚合物板相似的行为，并演示了小事件如何引发更大的断层，简单的语言总结我们已经建立了一个机器，挤压一个3-这是一个巨大的断层，它是一个巨大的花岗岩板块，产生一系列滑动事件，自发地破坏岩石内的预切平面断层，类似于地震如何破坏地球内的断层。虽然大多数岩石力学机器上产生的滑动事件在整个样品中破裂，但我们在这种大规模下产生的滑动事件更接近自然地震，因为破裂通常在岩石样品仅传播到一半后就停止了。我们描述了一个模型，使我们能够量化在哪里以及为什么破裂停止作为故障和摩擦性能的应力分布的函数。通过将模型与实验相匹配，我们估计了断层的断裂能。该模型还可以用来显示小地震如何为更大的地震准备断层。
Earthquakes are dynamic rupture events that initiate, propagate, and terminate on faults within the Earth's crust. Understanding rupture termination is essential for accurately estimating the maximum magnitude earthquake a region might experience. We study termination on sequences of M - 2.5 earthquakes that rupture a 3-m granite laboratory sample. At this large scale, nucleation, propagation, and termination are either completely or partially confined within the sample-unique observations for experiments on rock. We compare measured termination locations to estimates from a fracture mechanics-based model to quantify the fracture energy of the laboratory earthquakes, which compare well with estimates from small natural quakes. Our results provide a mathematical framework that links micrometer-scale friction parameters to meter-scale earthquake mechanics, shows that a 3-m slab of granite can behave similar to a 200-mm sheet of glassy polymer, and demonstrates how small events can prime a fault for larger, damaging ones.Plain Language Summary We have built a machine that squeezes a 3-m long slab of granite to generate sequences of slip events that spontaneously rupture a precut planar fault within the rock, similar to how earthquakes rupture faults within the Earth. While slip events generated on most rock mechanics machines rupture through the entire sample, the slip events we generate at this large scale are more realistic of natural earthquakes because rupture often stops after propagating only part-way down the rock sample. We describe a model that allows us to quantify where and why a rupture stops as a function of the stress distribution on the fault and friction properties. By matching the model to the experiment we estimate the fault's fracture energy. The model can also be used to show how small earthquakes can prepare a fault for a larger one.