FAULT KINEMATIC ANALYSIS IN SERPENTINITE ALONG CUESTA RIDGE, CENTRAL CALIFORNIA COAST

The San Gregorio-Hosgri fault is one of several strike-slip faults accommodating North America–Pacific plate dextral transform displacement that presents significant seismic hazards for the central California Coast. However, slip along this fault remains poorly constrained and the primary mechanism accommodating north-to-south differential slip along the San Gregorio-Hosgri Fault is unknown. One model for this differential slip suggests that slip along dextral faults in the Nacimiento block allows for southward-decreasing slip on the San Gregorio-Hosgri Fault. Alternatively, southward decreasing slip along the San Gregorio–Hosgri fault could have been accommodated by shortening along thrust faults within the Nacimiento block. Preliminary fault kinematic data from outcrops of Franciscan Complex serpentinite in the vicinity of Cuesta Ridge and which connect segments of the Oceanic and West Huasna faults yields strongly concentrated T-axes with subhorizontal NW–SE orientations and weakly-concentrated P-axes that trend NNE–SSW with variable plunge. Further analysis of serpentinite faulting in this area will provide insight to slip along the Oceanic-West Huasna Fault and its implications for regional tectonics.