SoCal Faults Reach 1,000-Year Stress Peak, Raising Risk of Joint Rupture
University of Hawaii at Manoa researchers say stress on Southern California's San Andreas and San Jacinto faults is at its highest level in 1,000 years, signaling a potential large rupture involving both faults. The Cajon Pass may act as an “earthquake gate,” sometimes blocking and other times allowing cross-fault ruptures, with major metro areas like Los Angeles, San Bernardino, Riverside, and the Coachella Valley at risk. The study uses a physics-based model fed by 1,000 years of regional earthquake history and notes more than 160 years since the last large quake.