Study Finds Stress on San Andreas and San Jacinto Faults at Millennial High
University of Hawaii researchers say stress on Southern California's major faults has reached levels not seen in 1,000 years, raising concerns for future seismic hazard assessments.
University of Hawaii at Manoa scientists report that stress accumulation on the San Andreas and San Jacinto fault systems in Southern California has reached its highest point in a millennium, according to a new physics-based model. The model incorporated 1,000 years of regional earthquake history to estimate current stress levels.
"The region may be capable of a large through-going rupture involving both fault systems," said researcher Liliane Burkhard. She added that the Cajon Pass could sometimes act as a barrier and other times allow a joint rupture, potentially linking the two faults in a single event.
The study indicates that, with more than 160 years since the last major rupture, stress that would normally be released by large earthquakes has continued to build. Densely populated areas such as Los Angeles, San Bernardino, Riverside and the Coachella Valley could be significantly impacted if a combined fault rupture occurs.
The San Andreas Fault marks the boundary between the Pacific and North American tectonic plates and extends roughly 650 miles, with subsidiary faults like the Hayward branching from it.