Overview
- An international team led by Liliane Burkhard published a peer‑reviewed study on June 3 that used a four‑dimensional earthquake‑cycle model to estimate present‑day stress on the southern San Andreas and San Jacinto systems.
- The model shows stress on key segments at or above the highest levels in the last 1,000 years, with peak values of about 3.6 MPa on the San Jacinto–Bernardino section and about 2.8 MPa on the Mojave South San Andreas section; MPa is a unit of pressure used to quantify tectonic stress.
- Cajon Pass is identified as an "earthquake gate" whose current stress alignment makes it more likely that a rupture would jump between the two fault systems, which historically has both happened and failed to happen at that junction.
- The authors stress the result is not a short‑term forecast of when an earthquake will occur but a physics‑based hazard assessment intended to inform infrastructure planning, emergency preparedness, and risk scenarios.
- A joint rupture crossing Cajon Pass would threaten densely populated corridors and critical links — highways, rail lines and energy networks serving Los Angeles, San Bernardino, Riverside and the Coachella Valley — so officials and planners should use the study’s scenarios to prioritize resilience and response measures.