Microscale characterization of rupture nucleation unravels precursors to faulting in rocks
Microscale characterization of rupture nucleation unravels precursors to faulting in rocks
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DOI：
10.1016/j.epsl.2017.08.002
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发表时间：
2017-10
影响因子：
5.3
通讯作者：
François Renard;B. Cordonnier;M. Kobchenko;Neelima Kandula;J. Weiss;Wenlu Zhu
中科院分区：
文献类型：
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作者：
François Renard;B. Cordonnier;M. Kobchenko;Neelima Kandula;J. Weiss;Wenlu Zhu
前兆信号，即动态断层之前的微尺度破坏的表现，是地震预报和风险减轻的关键。前兆的探测主要依赖于在现场和实验室实验中使用安装在离破裂区一定距离处的传感器进行的测量。在故障成核和传播过程中积累的连续微尺度损伤的直接观测是稀缺的。利用X射线透射式三轴变形仪首次获得了岩石脆性破坏过程中损伤演化的高分辨率三维定量信息。动态显微层析成像图像记录了一系列的损坏特征和不同的故障增长模式。各种变形机制之间的相互作用可以导致正的、负的或恒定的净体积变化。因此，岩石密度和声波速度断层前的变化，预计会在不同的构造环境中变化，从而使故障预测本质上依赖于岩石类型的深度。
Precursory signals, manifestations of microscale damage that precedes dynamic faulting, are key to earthquake forecasting and risk mitigation. Detections of precursors have primarily relied on measurements performed using sensors installed at some distance away from the rupture area in both field and laboratory experiments. Direct observations of continuous microscale damage accumulated during fault nucleation and propagation are scarce. Using an X-ray transparent triaxial deformation apparatus, we show the first quantitative high resolution three-dimensional (3D) information about damage evolution of rocks undergoing brittle failure. The dynamic microtomography images documented a spectrum of damage characteristics and different fault growth patterns. The interplay between various deformation mechanisms can result in either a positive, negative, or constant net volume change. Consequently, changes in rock density and acoustic wave velocities before faulting are expected to vary in different tectonics settings, hence making failure forecasting intrinsically dependent on rock type at depth.