Kinematic models of deformation in Southern California constrained by geologic and geodetic data

Abstract

Using a standardized fault geometry based on the Community Block Model, we create two analytic block models of the southern California fault system. We constrain one model with only geodetic data. In the other, we assign a priori slip rates to the San Andreas, Garlock, Helendale, Newport-Inglewood, Owens Valley, Sierra Madre, and Chino faults to create a joint geologic and geodetic model, using the a priori slip rates to refine the results in areas with limited geodetic data. Our results for the San Andreas fault are consistent with geologic slip rates in the north and south, but across the Big Bend area we find its slip rates to be slower than geologic rates. Our geodetic model shows right lateral slip rates of 19.8 + 1.3 mm/yr in the Mojave area and 17.3 ± 1.6 mm/yr near the Imperial fault; the San Gorgonio Pass area displays a left lateral slip rate of 1.8 + 1.7 mm/yr. Our joint geologic and geodetic model results include right lateral slip rates of 18.6 + 1.2 mm/yr in the Mojave area, 22.1 ± 1.6 mm/yr near the Imperial fault, and 9.5 1.4 mm/yr in the San Gorgonio Pass area. Both models show high values (10-13 1 mm/yr) of right lateral slip to the east of the Blackwater fault along the Goldstone, Calico, and Hidalgo faults. We show that substantially different block geometries in the Mojave can produce statistically similar model results due to sparse geodetic data.