In the Saticoy field , oil is trapped both in pinchouts of updipping permeable sedimentary units within units of lesser permeability , and in sedimentary units which end abruptly at the Oak Ridge Thrust Fault ; oil migrating upwards within permeable units , in this case , encounters an impermeable barrier of rock placed there by the fault . Horizontally , the fault defines the course of the Santa Clara River and the northern base of the hills south of the river ( including South Mountain ) , and is part of the fault complex responsible for the 1994 Northridge earthquake . The fault bounds the field on the southeast ; many of the oil-bearing units have been deformed so as to be aligned almost vertically , especially in the lower zones . The sedimentary units are predominantly turbidites , and are of Pleistocene and Pliocene age . From the top down , the units are the Pleistocene Santa Barbara Formation , which contains the producing horizon labeled the " Upper F Zone " ; and the Upper Pliocene Pico Sand , which contains the horizons labeled " Lower F Zone " , " G Zone " , " H Zone " , " I Zone " , " J Zone " , and " K Zone . " Most of the oil is between below ground surface
1994 Northridge earthquake
1994 Northridge earthquake
Saticoy Oil Field