Oceanside and Thirtymile Bank blind thrusts: Implications for earthquake hazards in coastal southern California

We define an active blind thrust system in offshore southern California tha t extends from Los Angeles south to the United States-Mexico international border. These blind thrusts formed by tectonic inversion of Miocene extensi onal detachments. We attribute the 1986 Oceanside (M-L 5.3) earthquake, loc al uplift of marine terraces, seafloor fold scarps, and observed geodetic c onvergence to motion on these faults. Single and multisegment fault rupture scenarios suggest the potential for large (M 7.1-7.6) but infrequent earth quakes that mould affect the Los Angeles and San Diego metropolitan areas.