Overview
- A peer‑reviewed paper published in June 2026 reports that stress on multiple segments of Southern California’s San Andreas and San Jacinto fault systems has reached or exceeded levels seen in the past 1,000 years.
- Researchers built a physics‑based computer model fed with a reconstructed 1,000‑year earthquake history from geological records to estimate how stress has accumulated and migrated across the region.
- The study singles out Cajon Pass as a critical junction that can sometimes block ruptures and sometimes allow them to jump between the two fault systems, which would create a much larger, more damaging event.
- Authors and independent experts stress the work is not a short‑term earthquake forecast and instead recommend that the scenario results be used to update hazard assessments, reinforce infrastructure, and sharpen emergency plans.
- The paper notes model uncertainties in input data and rupture behavior, so officials are advised to combine these physics‑based scenarios with existing probabilistic forecasts when planning for impacts to Los Angeles, San Bernardino, Riverside and the Coachella Valley.