Overview
- A peer-reviewed study published in early June 2026 used a four-dimensional physics model built from roughly 1,000 years of earthquake records to simulate stress build-up, stress transfer and crustal relaxation across southern California faults.
- The team identified Cajon Pass as an "earthquake gate" whose stress state controls whether ruptures stay on one fault or jump to both the San Andreas and San Jacinto systems.
- The model reports present-day stress estimates of about 3.6 MPa on the San Jacinto–Bernardino section and about 2.8 MPa on Mojave South and indicates conditions favoring joint San Andreas–San Jacinto ruptures have been possible since around 1930.
- Authors stress the results are not a short-term timing forecast but scenario information intended to guide hazard assessment, infrastructure resilience and emergency-preparedness planning.
- A multi-fault rupture through Cajon Pass would threaten major highways, rail lines and energy corridors into the Los Angeles region, and the study’s scenarios complement existing USGS probabilistic forecasts such as the roughly 31% chance of M≥7.5 in the Los Angeles area within 30 years.