Pervasive Foreshock Activity Across Southern California
Pervasive Foreshock Activity Across Southern California
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DOI：
10.1029/2019gl083725
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发表时间：
2019-06
影响因子：
5.2
通讯作者：
D. Trugman;Z. Ross
中科院分区：
文献类型：
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作者：
D. Trugman;Z. Ross
据记载，在所有主震地震之前发生的前震不到一半。这些观测结果很难与实验室地震实验和地震成核的理论模型相一致，这两者都表明前震活动应该几乎无处不在。在这里，我们使用最先进的高分辨率地震目录来研究2008-2017年南加州M4级和更大的主震前震序列。这个高度完整的目录为研究较小震级的前兆地震活动提供了新的机会。本目录中72%的主震之前都有前震活动，与当地背景地震活动率相比，前震活动明显增加。前震序列的持续时间从几天到几周不等，中位数为16.6天。结果表明，自然界中前震的发生比以前认为的更为普遍，我们对地震成核的理解可能会随着我们探测小地震能力的提高而提高。
Foreshocks have been documented as preceding less than half of all mainshock earthquakes. These observations are difficult to reconcile with laboratory earthquake experiments and theoretical models of earthquake nucleation, which both suggest that foreshock activity should be nearly ubiquitous. Here we use a state‐of‐the‐art, high‐resolution earthquake catalog to study foreshock sequences of magnitude M4 and greater mainshocks in southern California from 2008–2017. This highly complete catalog provides a new opportunity to examine smaller magnitude precursory seismicity. Seventy‐two percent of mainshocks within this catalog are preceded by foreshock activity that is significantly elevated compared to the local background seismicity rate. Foreshock sequences vary in duration from several days to weeks, with a median of 16.6 days. The results suggest that foreshock occurrence in nature is more prevalent than previously thought and that our understanding of earthquake nucleation may improve in tandem with advances in our ability to detect small earthquakes.