According to the USGS map of the area, the earthquake occurred on or near the Oak Ridge Fault in an area south of South Mountain Road. The Oak Ridge Fault, south of Santa Paula, and the San Cayetano Fault located to the north of the city, transverse much of the Santa Clara River Valley, at one point separated by about one mile. The faults have been inching closer together and are among the most watched in the state by earthquake officials.
The USGS is part of the California Integrated Seismic Net team that includes Caltech and several universities among other members.
