Overview
- A peer‑reviewed study published this week reconstructed about 1,000 years of earthquakes and used a physics‑based model to estimate present‑day stress on the two fault systems.
- The team found stress on key segments of the San Andreas and San Jacinto faults at the highest levels seen in a millennium and described the network as critically loaded after more than 160 years without a major southern San Andreas rupture.
- Scientists identified Cajon Pass as an "earthquake gate," where the local alignment of stress could either block or allow a rupture to jump from one fault system to the other and create a much larger, multi‑fault event.
- Authors emphasized the findings are scenario‑based hazard information to guide emergency planning and infrastructure upgrades, not a short‑term forecast of when an earthquake will occur.
- If a through‑going rupture did happen, the study says it could threaten dense population and vital infrastructure corridors serving Los Angeles, San Bernardino, Riverside and the Coachella Valley, prompting calls for updated hazard assessments and resilience investments.