Earthquake gate stopping a San Andreas disaster under highest stress in 1K years
10 hours ago
- #San Andreas fault
- #earthquake risk
- #seismic research
- A Hollywood-like scenario: a major earthquake on the San Andreas fault could devastate Los Angeles, causing fires, landslides, and infrastructure damage.
- New research indicates that southern sections of the San Andreas and parts of the San Jacinto fault are at their highest stress levels in 1,000 years, raising the risk of a significant quake.
- An earthquake could cascade between these faults via the 'Cajon Pass earthquake gate,' spreading damage across a wider area, including north of LA through San Bernardino, Riverside, and the Coachella Valley simultaneously.
- There's a more than 50% chance of a magnitude 6.7 or higher earthquake along the southern San Andreas fault in the coming decades.
- The Cajon Pass can either stop or transmit large ruptures; in 1812, a magnitude 7.5 quake likely crossed it, affecting both fault systems and causing fatalities.
- If an earthquake crosses the Cajon Pass today, it could reach magnitude 7.4 to 7.8, severely impacting highways, railways, and energy corridors across multiple cities.
- Analysis of 1,000 years of seismic activity shows that earthquakes pass through the Cajon Pass when stress levels on both sides are similarly high, a condition approaching today.
- The San Jacinto Bernardino segment has the highest stress load in 1,000 years at 3.6 megapascals, while the San Andreas Mojave South segment records 2.8 megapascals.
- The stress difference between segments is now 0.8 megapascals; past simulations show ruptures occurred with a difference of only 0.3 megapascals.
- The key insight is that stress balance at the junction determines whether an earthquake remains contained or expands into a larger rupture.
- The study urges not panic but urgent preparation, advising city managers and emergency responders to plan for joint ruptures as a realistic, near-term risk.