What Controls Variations in Aftershock Productivity?
What Controls Variations in Aftershock Productivity?
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DOI：
10.1029/2019jb018111
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发表时间：
2020-02-01
影响因子：
3.9
通讯作者：
Goebel, Thomas H. W.
中科院分区：
文献类型：
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作者：
Dascher-Cousineau, Kelian;Brodsky, Emily E.;Goebel, Thomas H. W.
余震的数量随着主震规模的增加而增加，遵循一个明确的标度律。然而，偏离平均行为是常见的。这种可变性对于大地震来说尤其重要，因为余震的数量与震级相当的主震相差100倍。可观测的因素导致余震行为的差异吗？我们检查了1990年至2019年所有主震（M-W > 6.5）的余震生产力相对于全球平均水平的情况。全球地震生产力地图突出了构造机制的影响。地震深度、岩石圈年龄、板块边界类型与地震产率有较好的对应关系。我们通过编制源尺寸，辐射地震能量，应力降以及基于1990年至2017年最大地震的有限断层源反演的滑动不均匀性测量来研究主震属性的作用。在个别的基础上，应力降，归一化破裂宽度，和纵横比最强烈的余震生产力相关。多变量分析表明，一组特定的参数（倾角，岩石圈年龄，和归一化破裂面积）相结合，以及提高预测的余震生产力的交叉验证的数据集。我们的整体分析是一致的模型，在该模型中，附近的应力断层的体积丰度控制的余震生产力，而不是在源应力的变化。因此，我们建议一个补充的方法来预测余震的基础上地质和破裂属性，而不是单独的本地校准。
The number of aftershocks increases with mainshock size following a well-defined scaling law. However, excursions from the average behavior are common. This variability is particularly concerning for large earthquakes where the number of aftershocks varies by factors of 100 for mainshocks of comparable magnitude. Do observable factors lead to differences in aftershock behavior? We examine aftershock productivity relative to the global average for all mainshocks (M-W > 6.5) from 1990 to 2019. A global map of earthquake productivity highlights the influence of tectonic regimes. Earthquake depth, lithosphere age, and plate boundary type correspond well with earthquake productivity. We investigate the role of mainshock attributes by compiling source dimensions, radiated seismic energy, stress drop, and a measure of slip heterogeneity based on finite-fault source inversions for the largest earthquakes from 1990 to 2017. On an individual basis, stress drop, normalized rupture width, and aspect ratio most strongly correlate with aftershock productivity. A multivariate analysis shows that a particular set of parameters (dip, lithospheric age, and normalized rupture area) combines well to improve predictions of aftershock productivity on a cross-validated data set. Our overall analysis is consistent with a model in which the volumetric abundance of nearby stressed faults controls the aftershock productivity rather than variations in source stress. Thus, we suggest a complementary approach to aftershock forecasts based on geological and rupture properties rather than local calibration alone.