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Interseismic strain accumulation and the earthquake potential on the southern San Andreas fault system

Naturevolume 441pages968971 (2006) | Download Citation



The San Andreas fault in California is a mature continental transform fault that accommodates a significant fraction of motion between the North American and Pacific plates. The two most recent great earthquakes on this fault ruptured its northern and central sections in 1906 and 1857, respectively. The southern section of the fault, however, has not produced a great earthquake in historic times (for at least 250 years). Assuming the average slip rate of a few centimetres per year, typical of the rest of the San Andreas fault, the minimum amount of slip deficit accrued on the southern section is of the order of 7–10 metres, comparable to the maximum co-seismic offset ever documented on the fault1,2. Here I present high-resolution measurements of interseismic deformation across the southern San Andreas fault system using a well-populated catalogue of space-borne synthetic aperture radar data. The data reveal a nearly equal partitioning of deformation between the southern San Andreas and San Jacinto faults, with a pronounced asymmetry in strain accumulation with respect to the geologically mapped fault traces. The observed strain rates confirm that the southern section of the San Andreas fault may be approaching the end of the interseismic phase of the earthquake cycle.

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I thank R. Weldon and P. Segall for suggestions. This work was supported by the NSF and the Southern California Earthquake Center (SCEC). Original InSAR data are copyright of the European Space Agency, distributed by Eurimage, Italy, and acquired via the WInSAR Consortium. The ERS SAR imagery was processed using the JPL/Caltech software package ROI_PAC. The continuous GPS data were provided by the Scripps Orbit and Permanent Array Center (SOPAC), and the campaign GPS and EDM data were provided by the Crustal Motion Model v3 of SCEC.

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  1. Institute of Geophysics and Planetary Physics, Scripps Institution of Oceanography, University of California, California, San Diego, La Jolla, USA

    • Yuri Fialko


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Reprints and permissions information is available at npg.nature.com/reprintsandpermissions. The author declares no competing financial interests.

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Correspondence to Yuri Fialko.

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