Overview
- A peer‑reviewed study published in early June finds tectonic stress on the San Andreas and San Jacinto fault systems is at its highest level in at least 1,000 years, based on a long reconstructed earthquake record.
- Researchers identify Cajon Pass, where the two faults converge, as an 'earthquake gate' that can either block or allow ruptures to jump between faults and thereby enable a larger, multi‑fault event.
- The team combined geological evidence — displaced sediments, radiocarbon dating and tree‑ring records — with a four‑dimensional physics model that simulates stress buildup and transfer across faults.
- The authors stress the work is not a short‑term prediction of timing and present the results as hazard scenarios to guide emergency planning, infrastructure upgrades and updated risk assessments.
- The study heightens concern for major transportation, energy and water corridors serving Los Angeles, San Bernardino, Riverside and the Coachella Valley and recalls that the last region‑wide rupture of comparable scale occurred in 1857.