San Andreas San Jacinto faults highest stress in 1000 years Cajon Pass earthquake gate study
Anyone near the San Andreas now sits on crust under more strain than at any point in 1,000 years, per a peer-reviewed study in the Journal of Geophysical Research. It flags Cajon Pass, where the San Andreas and San Jacinto faults meet, as a gate that could let a rupture jump betw
Anyone living near the San Andreas is now sitting atop crust under more strain than at any point in the last 1,000 years. That is the central finding of a peer-reviewed study published June 3 in the Journal of Geophysical Research: Solid Earth, which reconstructed a full millennium of earthquake activity along the San Andreas and San Jacinto faults in Southern California. To build that picture, the international research team combined geological evidence including radiocarbon dating, tree-ring anomalies and historical records of ground ruptures, then fed it into a physics-based model of the earthquake cycle. The model tracks how stress has built and released across the fault network over centuries, and it shows present-day stress sitting higher than at any comparable point in the record. The study also identifies a specific feature that could shape a future rupture. Cajon Pass, the point northeast of San Bernardino where the San Andreas and San Jacinto faults converge, may act as what the researchers call an earthquake gate. Depending on conditions when a rupture begins, that gate could either keep the break confined to a single fault or allow it to cascade across both, which would enlarge the area and intensity of shaking. The work does not assign a date to any earthquake. What it offers is a clearer measurement of how loaded the system has become and which junction deserves the closest attention. For the millions who live and work along these faults, it underlines why building standards and emergency planning carry real weight. Source: University of Hawaii, Journal of Geophysical Research: Solid Earth