On the statistical significance of foreshock sequences in Southern California

Martijn P.A. van den Ende (1) , J.‐p. Ampuero (1)

1 GEOAZUR 7329 - Géoazur

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.

Domaines: Sciences de la Terre; Géophysique [physics.geo-ph]

Martijn P.A. van den Ende, J.‐p. Ampuero. On the statistical significance of foreshock sequences in Southern California. Geophysical Research Letters, 2020, 47 (3), ⟨10.1029/2019GL086224⟩. ⟨hal-02459387⟩