On the statistical significance of foreshock sequences in Southern California

This is a Preprint and has not been peer reviewed. The published version of this Preprint is available: https://doi.org/10.1029/2019GL086224. This is version 3 of this Preprint.


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Martijn van den Ende , Jean Paul Ampuero 


Earthquake foreshocks may provide information that is critical to short-term earthquake forecasting. However, foreshocks are far from ubiquitously observed, which makes the interpretation of ongoing seismic sequences problematic. Based on a statistical analysis, Trugman & Ross (2019) suggested that as much as 72% of all mainshocks in Southern California is preceded by foreshock sequences. In this study, we re-assess the analysis of Trugman & Ross (2019), and we evaluate the impact of the assumptions made by these authors. Using an alternative statistical approach, we find that only 15 out of 46 mainshocks (33%) are preceded by significantly elevated seismicity rates. When accounting for temporal fluctuations in the background seismicity, only 18% of the analysed foreshock sequences remain unexplained by the background seismicity. These results imply that even in a highly complete earthquake catalogue, the majority of earthquakes do not exhibit detectable foreshock sequences.




Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics


Foreshocks, earthquake, california


Published: 2019-11-05 21:58

Last Updated: 2020-01-02 22:13

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CC BY Attribution 4.0 International

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