Geomorphic evidence for the geometry and slip rate of a young, low-angle thrust fault: Implications for hazard assessment and fault interaction in complex tectonic environments

•Young faults often undetected but potentially crucial for seismic hazard assessments.•First geomorphic evidence for the Southern San Cayetano fault (SSCF).•10Be dating of offset terraces records Holocene slip rate of 1.3+0.5−0.3 mm yr−1.•SSCF has major implications for seismic hazard in southern California.