Linear Relationship Between Aftershock Productivity and Seismic Coupling in the Northern Chile Subduction Zone
Linear Relationship Between Aftershock Productivity and Seismic Coupling in the Northern Chile Subduction Zone
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DOI：
10.1029/2019jb017764
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发表时间：
2019-08-01
影响因子：
3.9
通讯作者：
Schurr, B.
中科院分区：
文献类型：
--
作者：
Hainzl, S.;Sippl, C.;Schurr, B.
众所周知，相同震级的不同主震的余震生产力差异很大，这不能简单地用随机波动来解释。除了可变的来源机制外，不同的流变特性可能是所观察到的变化的原因。在这里，我们表明，对于智利北部俯冲带，余震生产力与沿俯冲界面的机械耦合程度呈线性关系。使用SIPPL等人的地震目录。(2018)，由2007-2014年间的100,000多次事件组成，以及从地震间大地形变数据推断的三种不同的耦合图，我们表明，观测到的余震数量明显低于根据Bath定律预测的数量。此外，在最高80公里处，生产力随着深度的增加而有系统地衰减，而b值则增加。结果表明，这种无余震现象和观测到的深度相关性可以简单地用生产力与耦合系数之间的线性关系来解释，只有在完全耦合的情况下才能得到Bath定律。我们的结果表明，耦合图可能对预测余震生产力是有用的，反之亦然。
The aftershock productivity is known to strongly vary for different mainshocks of the same magnitude, which cannot be simply explained by random fluctuations. In addition to variable source mechanisms, different rheological properties might be responsible for the observed variations. Here we show, for the subduction zone of northern Chile, that the aftershock productivity is linearly related to the degree of mechanical coupling along the subduction interface. Using the earthquake catalog of Sippl et al. (2018, ), which consists of more than 100,000 events between 2007 and 2014, and three different coupling maps inferred from interseismic geodetic deformation data, we show that the observed aftershock numbers are significantly lower than expected from the Bath's law. Furthermore, the productivity decays systematically with depth in the uppermost 80 km, while the b value increases. We show that this lack of aftershocks and the observed depth dependence can be simply explained by a linear relationship between the productivity and the coupling coefficient, leading to Bath law only in the case of full coupling. Our results indicate that coupling maps might be useful to forecast aftershock productivity and vice versa.