California Faults Reach 1,000-Year Stress Peak, Hint at a Possible Joint Rupture

A University of Hawai‘i–led study using a 1,000-year seismic history finds the San Andreas and San Jacinto faults in Southern California are under stress at or near the highest levels seen in the past millennium, with Cajon Pass potentially acting as an “earthquake gate” that could allow a joint rupture across both faults. The results could refine hazard assessments and inform infrastructure planning and preparedness, but do not predict when an earthquake will happen.