San Andreas Fault hits highest stress level in 1,000 years, study finds

Key Points:

• New research from the University of Hawaii at Manoa reveals that stress along the San Andreas and San Jacinto faults in Southern California has reached its highest levels in 1,000 years, raising concerns about seismic hazards in the densely populated region.
• Scientists warn that the region may experience a large rupture involving both fault systems simultaneously, with the Cajon Pass potentially acting as an "earthquake gate" that can either block or allow such joint ruptures.
• Using a physics-based model fed with 1,000 years of earthquake data, researchers found that stress accumulation is at historic highs, with over 160 years since the last major rupture, indicating a critically loaded fault system.
• A simultaneous rupture of both faults could significantly impact major urban areas including Los Angeles, San Bernardino, Riverside, and the Coachella Valley, emphasizing the need for updated seismic hazard assessments.
• The San Andreas Fault, stretching about 650 miles and serving as the boundary between the Pacific and North American plates, remains a primary focus for earthquake preparedness due to its potential for large-scale seismic events.