Tracking the Spatio‐Temporal Evolution of Foreshocks Preceding the Mw 6.1 2009 L’Aquila Earthquake
Tracking the Spatio‐Temporal Evolution of Foreshocks Preceding the Mw 6.1 2009 L’Aquila Earthquake
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DOI：
10.1029/2021jb023888
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发表时间：
2022-03
期刊：
影响因子：
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通讯作者：
L. Cabrera;P. Poli;W. Frank
中科院分区：
文献类型：
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作者：
L. Cabrera;P. Poli;W. Frank
断层作用如何导致大地震是地震学中的一个基本问题。为了更好地约束这一震前阶段，我们通过模板匹配创建了一个密集的地震目录，以分析2009年发生在意大利中部的Mw 6.1拉奎拉地震的地震阶段。我们在时间上估计了几个物理参数，如变异系数，地震矩释放，有效应力降，并分析时空模式，以研究序列的演化和地震相互作用。我们观察到，地震阶段经历了地震活动率的多次加速，我们将其分为两个具有不同特征和特征的主要序列：第一部分表现出弱地震相互作用，准连续的力矩释放，缓慢的空间迁移模式，以及较低的有效应力降，指向地震过程。第二个序列表现出强烈的时间集群，快速的地震活动扩展，和一个更大的有效应力降典型的应力转移过程。我们解释了两个序列之间的地震活动行为的差异，作为不同的物理机制，由不同的物理性质的断层系统控制。我们的结论是，拉奎拉地震之前，一个复杂的准备，由不同的物理过程在不同的时间尺度上具有不同的物理性质的断层。
How faulting processes lead to a large earthquake is a fundamental question in seismology. To better constrain this pre‐seismic stage, we create a dense seismic catalog via template matching to analyze the precursory phase of the Mw 6.1 L’Aquila earthquake that occurred in central Italy in 2009. We estimate several physical parameters in time, such as the coefficient of variation, the seismic moment release, the effective stress drop, and analyze spatio‐temporal patterns to study the evolution of the sequence and the earthquake interactions. We observe that the precursory phase experiences multiple accelerations of the seismicity rate that we divide into two main sequences with different signatures and features: the first part exhibits weak earthquake interactions, quasi‐continuous moment release, slow spatial migration patterns, and a lower effective stress drop, pointing to aseismic processes. The second sequence exhibits strong temporal clustering, fast seismicity expansion, and a larger effective stress drop typical of a stress transfer process. We interpret the differences in seismicity behaviors between the two sequences as distinct physical mechanisms that are controlled by different physical properties of the fault system. We conclude that the L’Aquila earthquake is preceded by a complex preparation, made up of different physical processes over different time scales on faults with different physical properties.