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Explaining the paleo-event hiatus in California

Morgan T. Page, Edward H. Field, Kevin R. Milner, & Nicholas J. van der Elst

Published August 13, 2019, SCEC Contribution #9511, 2019 SCEC Annual Meeting Poster #028

There has been a notable absence of large earthquakes in the last century in California, particularly on the highest slip-rate faults. This lull was noted by Jackson (2014), who argued that the observed data precluded Poissonian or lognormal earthquake occurrence, provided that earthquake times between distant sites were not correlated. We analyze the statistical significance of the hiatus given that earthquake times between sites may in fact be correlated by elastic rebound and aftershock-driven clustering effects. We look at three models, the UCERF3-TD model, which includes elastic rebound effects; the UCERF3-ETAS model, which includes both elastic rebound and aftershock clustering; and a critical ETAS model that includes aftershock clustering with a “long reach” in both space and time. UCERF3-ETAS predicts that the currently observed paleoseismic hiatus has a 3.5% chance of occurring. This is due to both elastic rebound effects (stress shadows from the 1857 and 1906 earthquakes) and clustering effects.

Key Words
paleoseismic hiatus, UCERF3, ETAS

Page, M. T., Field, E. H., Milner, K. R., & van der Elst, N. J. (2019, 08). Explaining the paleo-event hiatus in California. Poster Presentation at 2019 SCEC Annual Meeting.

Related Projects & Working Groups
Earthquake Forecasting and Predictability (EFP)