A scaling law for slow earthquakes
A scaling law for slow earthquakes
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DOI：
10.1038/nature05780
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发表时间：
2007-05-03
期刊：
影响因子：
64.8
通讯作者：
Uchide, Takahiko
中科院分区：
文献类型：
--
作者：
Ide, Satoshi;Beroza, Gregory C.;Uchide, Takahiko
近年来，发现了一系列地震异常现象，包括深幕式地震（1）、低频地震（2）、甚低频地震（3）、慢滑事件（4）和无声地震（5-9）。每一次地震都被证明是由剪切滑动引起的，就像常规地震一样，但特征持续时间更长，辐射的地震能量要少得多。在这里，我们表明，这些慢事件遵循一个简单的，统一的标度关系，清楚地区分他们的行为从定期地震。我们发现它们的地震矩与特征持续时间成正比，矩率函数为常数，谱高频衰减为f（-1）。这种标度和频谱特性表明，它们可以被认为是同一现象的不同表现，它们构成了一个新的地震类别。观测到的这些事件的破裂速度的尺度依赖性可以解释由一个恒定的低应力降模型或扩散常数滑移模型。这种新的标度律统一了不同类别的慢地震事件，并可能导致更好地了解板块俯冲过程和大地震的产生。
Recently, a series of unusual earthquake phenomena have been discovered, including deep episodic tremor(1), low-frequency earthquakes (2), very-low-frequency earthquakes(3), slow slip events(4) and silent earthquakes(5-9). Each of these has been demonstrated to arise from shear slip, just as do regular earthquakes, but with longer characteristic durations and radiating much less seismic energy. Here we show that these slow events follow a simple, unified scaling relationship that clearly differentiates their behaviour from that of regular earthquakes. We find that their seismic moment is proportional to the characteristic duration and their moment rate function is constant, with a spectral high-frequency decay of f(-1). This scaling and spectral behaviour demonstrates that they can be thought of as different manifestations of the same phenomena and that they comprise a new earthquake category. The observed scale dependence of rupture velocity for these events can be explained by either a constant low-stress drop model or a diffusional constant-slip model. This new scaling law unifies a diverse class of slow seismic events and may lead to a better understanding of the plate subduction process and large earthquake generation.