Similarity of fast and slow earthquakes illuminated by machine learning
Similarity of fast and slow earthquakes illuminated by machine learning
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DOI：
10.1038/s41561-018-0272-8
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发表时间：
2019-01-01
影响因子：
18.3
通讯作者：
Marone, Chris
中科院分区：
文献类型：
--
作者：
Hulbert, Claudia;Rouet-Leduc, Bertrand;Marone, Chris
构造断层以一系列模式失效，从地震到慢滑事件。快速地震的物理学可以用粘滑摩擦和弹性动力学破裂来很好地描述；然而，对慢速地震却知之甚少。关键问题仍然是破裂如何准动态传播，它们是否遵循与普通地震不同的标度规律，以及单个断层是否可以容纳多个滑动模式。我们报道了实验室的地震，并表明慢滑和快滑模式之前都有一系列微破裂事件，这些微破裂事件以一种预示灾难性破坏的方式辐射弹性能量。通过机器学习，我们发现，在1-10 Mpa的正应力下，石英断层泥剪切过程中产生的声发射可以预测实验室地震的发生时间和持续时间。实验室慢地震的峰值滑动速度达到1×10~(-4)m S(~(-1))量级，不辐射高频弹性能，与构造慢滑动一致。实验室快地震即将发生的早期阶段产生的声音信号系统地大于慢滑事件的声音信号。在这里，我们表明，粘滑和蠕滑破坏模式的广泛范围是可以预测的，并共享共同的机制，这表明灾难性的地震破坏之前可能有一套有组织的，潜在的可预测的过程。
Tectonic faults fail in a spectrum of modes, ranging from earthquakes to slow slip events. The physics of fast earthquakes are well described by stick-slip friction and elastodynamic rupture; however, slow earthquakes are poorly understood. Key questions remain about how ruptures propagate quasi-dynamically, whether they obey different scaling laws from ordinary earthquakes and whether a single fault can host multiple slip modes. We report on laboratory earthquakes and show that both slow and fast slip modes are preceded by a cascade of micro-failure events that radiate elastic energy in a manner that foretells catastrophic failure. Using machine learning, we find that acoustic emissions generated during shear of quartz fault gouge under normal stress of 1-10 MPa predict the timing and duration of laboratory earthquakes. Laboratory slow earthquakes reach peak slip velocities of the order of 1 x 10(-4) m s(-1) and do not radiate high-frequency elastic energy, consistent with tectonic slow slip. Acoustic signals generated in the early stages of impending fast laboratory earthquakes are systematically larger than those for slow slip events. Here, we show that a broad range of stick-slip and creep-slip modes of failure can be predicted and share common mechanisms, which suggests that catastrophic earthquake failure may be preceded by an organized, potentially forecastable, set of processes.