Loading of the San Andreas fault by flood-induced rupture of faults beneath the Salton Sea

Nature Geoscience
By: , and 

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Abstract

The southern San Andreas fault has not experienced a large earthquake for approximately 300 years, yet the previous five earthquakes occurred at ~180-year intervals. Large strike-slip faults are often segmented by lateral stepover zones. Movement on smaller faults within a stepover zone could perturb the main fault segments and potentially trigger a large earthquake. The southern San Andreas fault terminates in an extensional stepover zone beneath the Salton Sea—a lake that has experienced periodic flooding and desiccation since the late Holocene. Here we reconstruct the magnitude and timing of fault activity beneath the Salton Sea over several earthquake cycles. We observe coincident timing between flooding events, stepover fault displacement and ruptures on the San Andreas fault. Using Coulomb stress models, we show that the combined effect of lake loading, stepover fault movement and increased pore pressure could increase stress on the southern San Andreas fault to levels sufficient to induce failure. We conclude that rupture of the stepover faults, caused by periodic flooding of the palaeo-Salton Sea and by tectonic forcing, had the potential to trigger earthquake rupture on the southern San Andreas fault. Extensional stepover zones are highly susceptible to rapid stress loading and thus the Salton Sea may be a nucleation point for large ruptures on the southern San Andreas fault.

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Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Loading of the San Andreas fault by flood-induced rupture of faults beneath the Salton Sea
Series title Nature Geoscience
DOI 10.1038/ngeo1184
Volume 4
Year Published 2011
Language English
Publisher Nature Pub. Group
Contributing office(s) Woods Hole Coastal and Marine Science Center
Description 7 p.
First page 486
Last page 492
Country Mexico, United States
State California
Other Geospatial Salton Sea
Online Only (Y/N) N
Additional Online Files (Y/N) N