Multiscale Brittle-Ductile Coupling and Genesis of Slow Earthquakes
Multiscale Brittle-Ductile Coupling and Genesis of Slow Earthquakes
复制标题
多尺度脆性耦合与慢地震的成因
DOI：
10.1007/s00024-008-0326-8
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发表时间：
2008
期刊：
影响因子：
--
通讯作者：
D. Yuen
中科院分区：
文献类型：
--
作者：
K. Regenauer‐Lieb;D. Yuen
我们首次尝试将慢地震解释为级联热机械不稳定性。为了实现这一目标，我们研究了截然不同的时间尺度上的脆性耦合热机械模拟。最大尺度的模型由随机扰动弹粘塑性大陆岩石圈的横截面组成，规模约为 100 × 100 km，没有其他初始结构。最小尺度模型研究大模型的公里尺度分段，局部分辨率为 40 × 40 m。该模型受到施加在两侧的恒定延伸速度的影响。我们假设顶部表面是自由的，并且沿其他边界的切向应力为零。延伸由模型两侧应用的 1 cm/a 速度边界条件驱动。这是最简单的边界条件，使其成为理解具有多尺度脆性耦合的自然系统行为的理想起点。局部化反馈被观察为脆性上地壳中的断层和弹粘塑性下地壳中的延性剪切。在此过程中，脆性断层可能会以发震速率破裂，例如，在 102–103ms−1 时发生，而粘性剪切带的传播速率要慢得多，高达 3 × 10−9ms−1。应变率的这种鲜明对比导致了脆性转变时复杂的短时尺度相互作用。我们利用新模拟中的多尺度功能来理解潜在的热力学，跨越截然不同的时间和长度尺度。
We present the first attempt to explain slow earthquakes as cascading thermal-mechanical instabilities. To attain this goal we investigate brittle-ductile coupled thermal-mechanical simulation on vastly different time scales. The largest scale model consists of a cross section of a randomly perturbed elasto-visco-plastic continental lithosphere on the order of 100 × 100 km scale with no other initial structures. The smallest scale model investigates a km-scale subsection of the large model and has a local resolution of 40 × 40 m. The model is subject to a constant extension velocity applied on either side. We assume a free top surface and with a zero tangential stress along the other boundaries. Extension is driven by velocity boundary conditions of 1 cm/a applied on either side of the model. This is the simplest boundary condition, and makes it an ideal starting point for understanding the behavior of a natural system with multiscale brittle-ductile coupling. Localization feedback is observed as faulting in the brittle upper crust and ductile shearing in an elasto-viscoplastic lower crust. In this process brittle faulting may rupture at seismogenic rates, e.g., at 102–103ms−1, whereas viscous shear zones propagate at much slower rates, up to 3 × 10−9ms−1. This sharp contrast in the strain rates leads to complex short-time-scale interactions at the brittle-ductile transition. We exploit the multiscale capabilities from our new simulations for understanding the underlying thermo-mechanics, spanning vastly different, time- and length-scales.
影响因子：
64.8
作者：
Ide, Satoshi;Beroza, Gregory C.;Uchide, Takahiko
通讯作者：
Uchide, Takahiko