Testing a step-over model of the southern San Andreas fault at Durmid Hill: Final Report for 2012 SCEC Grant

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Database of the Southern California Earthquake Center

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Main findings: 1. The southernmost San Andreas fault is experiencing contraction and strike slip strains and is therefore unlikely to be a future nucleation point for the next “BIG ONE”. 2. The southern San Andreas fault has an additional, active strand that is near the shoreline of the Salton Sea. The San Andreas fault zone is thus at least 3 km wide in this area. 3. This SHORELINE strand of the San Andreas fault was active in the Holocene, and may be continuous with an ~30 km-long northwest-striking deformation boundary detected in many INSAR datasets in the urban centers of Palm Springs, Palm Desert, Cathedral City, Rancho Mirage, and La Quinta (Martin, 2011; Tong et al., 2011). 4. There is little evidence for interactions with the NNE-striking left-oblique Extra fault zone on the northeast shore of the Salton Sea.