The ‘earthquake gate’ stopping a San Andreas disaster is under its highest stress in 1,000 years

Key Points:

• New research indicates that the southern San Andreas fault and parts of the San Jacinto fault in Southern California are at their highest stress levels in 1,000 years, increasing the likelihood of a major earthquake.
• The study highlights the Cajon Pass as an "earthquake gate" where seismic activity could transfer between the two faults, potentially causing a large joint rupture with magnitudes between 7.4 and 7.8.
• Historical data and simulations show that when stress levels on both sides of the Cajon Pass are similar and high, earthquakes can propagate through the junction, a condition that current measurements suggest is approaching.
• A joint rupture could severely impact critical infrastructure across multiple cities including Los Angeles, San Bernardino, Riverside, and the Coachella Valley, affecting highways, railways, and energy corridors simultaneously.
• Researchers urge city officials and emergency responders to urgently prepare for the possibility of a large joint earthquake event, emphasizing that the risk is significant and growing rather than a remote worst-case scenario.