Analysis of Crustal Deformation along a Transect Across the Pacific-North American Plate Boundary Passing through San Luis Obispo

Event Center A & B

In California, where population is dense and tectonic activity is high, it is vital to better understand plate movement to prepare for natural disaster. By estimating slip rates of faults in California, we can better prioritize areas for preventative safety measures. This study contains a geophysical analysis of plate movement in a transect across the Pacific-North American plate boundary passing through San Luis Obispo California. The purpose of study was to analyze movement of the San Andreas Fault as well as adjacent faults to determine relative contributions to plate movement as a whole. Within the upper crust, the Pacific and North American plates are locked together as a result of friction on the fault plates. Below the brittle-ductile transition, fault creep occurs, which leads to bending of the upper crust, which can be measured by GPS. Previously published GPS site velocities from the San Luis Obispo transect were used to infer the slip rates along each of the faults in the transect by comparing the observed GPS velocity profile, with the profile predicted by over 21,000 combinations of fault slip rates, using the locking depths inferred from seismicity. The slip rate combination that produced a velocity profile that best adhered to the observed velocity profile resulted in the following slip rates: Hosgri-San Gregornio fault, 4mm/yr.; Rinconada fault, 0mm/yr.; San Andreas fault, 32mm/yr.; Hilton Creek fault, 4mm/yr.; White Mountain fault, 4mm/yr.; and Fish Lake fault, 2mm/yr.