LATE QUATERNARY ACTIVITY OF THE PINTO MOUNTAIN FAULT AT THE OASIS OF MARA: IMPLICATIONS FOR THE EASTERN CALIFORNIA SHEAR ZONE
Assuming that average displacement during prehistoric earthquakes along the Pinto Mountain fault is similar to the recent 1999 Hector Mine and 1992 Landers surface ruptures (~3 m), five to six events in the last 11.1-14.1 ka yields a slip rate of about 1.1-1.6 mm/yr. Since faulting is thought to have initiated on the Garlock and the Pinto Mountain faults at the same time, the ratio of their slip rates and offsets should be proportional. Using a Quaternary offset of 16±3.6 km on the central segment of the Pinto Mountain fault and a Quaternary slip rate of 5-7 mm/yr with 48-64 km total offset on the Garlock fault, yields a Pinto Mountain slip rate of 1.3-2.3 mm/yr. A low slip rate on the Pinto Mountain fault supports a Mojave block rotation model where the pole of rotation lies south of the Pinto Mountain fault, illustrated by the concave southward curvature of both the Pinto Mountain and Garlock faults.