Coseismic fault lubrication by viscous deformation
Coseismic fault lubrication by viscous deformation
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DOI：
10.1038/s41561-021-00747-8
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发表时间：
2021-05
影响因子：
18.3
通讯作者：
G. Pozzi;N. De Paola;S. Nielsen;R. Holdsworth;T. Tesei;M. Thieme;S. Demouchy
中科院分区：
文献类型：
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作者：
G. Pozzi;N. De Paola;S. Nielsen;R. Holdsworth;T. Tesei;M. Thieme;S. Demouchy
尽管地震带来了危险，但我们仍然对控制传播破裂前沿后面的断层润滑和增强地面加速度的过程缺乏基本了解。实验室实验表明，断层材料在地震速度（>0.1 m s−1）下剪切时会急剧减弱。人们提出了几种由剪切加热引发的机制来解释断层的同震弱化，但这些机制都不能解释弱化的实验和地震学证据。在这里，我们表明，在实验室实验中，弱化与不同造岩矿物的模拟断层中地震滑移过程中达到的局部温度相关。断层强度按照简单的、依赖于材料的阿伦尼乌斯型定律演化。微观结构通过显示具有亚固相线粘性流典型纹理的主滑移区的发展来支持这一观察结果。我们证明，粘性变形（在亚固相线温度或超固相线温度下）是一种重要、广泛且可量化的同震润滑过程。这些高效断层润滑过程的运行意味着更多的能量可用于破裂传播和危险地震波的辐射。
Despite the hazard posed by earthquakes, we still lack fundamental understanding of the processes that control fault lubrication behind a propagating rupture front and enhance ground acceleration. Laboratory experiments show that fault materials dramatically weaken when sheared at seismic velocities (>0.1 m s−1). Several mechanisms, triggered by shear heating, have been proposed to explain the coseismic weakening of faults, but none of these mechanisms can account for experimental and seismological evidence of weakening. Here we show that, in laboratory experiments, weakening correlates with local temperatures attained during seismic slip in simulated faults for diverse rock-forming minerals. The fault strength evolves according to a simple, material-dependent Arrhenius-type law. Microstructures support this observation by showing the development of a principal slip zone with textures typical of sub-solidus viscous flow. We show evidence that viscous deformation (at either sub- or super-solidus temperatures) is an important, widespread and quantifiable coseismic lubrication process. The operation of these highly effective fault lubrication processes means that more energy is then available for rupture propagation and the radiation of hazardous seismic waves.