Petrillo Giuseppe, Lippiello Eugenio, Landes François P, Rosso Alberto
Department of Mathematics and Physics, University of Campania "L. Vanvitelli", Viale Lincoln 5, Caserta, 81100, Italy.
TAU, LRI, Univ. Paris-Sud, CNRS, INRIA, Université Paris-Saclay, Orsay, 91405, France.
Nat Commun. 2020 Jun 15;11(1):3010. doi: 10.1038/s41467-020-16811-7.
Aftershock occurrence is characterized by scaling behaviors with quite universal exponents. At the same time, deviations from universality have been proposed as a tool to discriminate aftershocks from foreshocks. Here we show that the change in rheological behavior of the crust, from velocity weakening to velocity strengthening, represents a viable mechanism to explain statistical features of both aftershocks and foreshocks. More precisely, we present a model of the seismic fault described as a velocity weakening elastic layer coupled to a velocity strengthening visco-elastic layer. We show that the statistical properties of aftershocks in instrumental catalogs are recovered at a quantitative level, quite independently of the value of model parameters. We also find that large earthquakes are often anticipated by a preparatory phase characterized by the occurrence of foreshocks. Their magnitude distribution is significantly flatter than the aftershock one, in agreement with recent results for forecasting tools based on foreshocks.
余震的发生具有标度行为特征,其指数相当普遍。同时,偏离普遍性已被提议作为区分余震和前震的一种工具。在此我们表明,地壳流变行为从速度弱化到速度强化的变化,是解释余震和前震统计特征的一种可行机制。更确切地说,我们提出了一个地震断层模型,将其描述为一个与速度强化粘弹性层耦合的速度弱化弹性层。我们表明,仪器目录中余震的统计特性在定量水平上得以恢复,且与模型参数值相当独立。我们还发现,大地震往往之前会有一个以发生前震为特征的准备阶段。它们的震级分布明显比余震的更平缓,这与基于前震的预测工具的近期结果一致。