California Faults Are Under Their Highest Stress in 1,000 Years, Stoking Fears of the ‘Big One’

The critical role of Cajon Pass Cajon Pass is the tectonically complex junction where the San Andreas and San Jacinto faults converge. It’s located near several densely populated communities, including Los Angeles, San Bernadino, Riverside, and Coachella Valley. Burkhard and her colleagues determined that Cajon Pass can act as a so-called “earthquake gate,” controlling whether large ruptures remain confined to a single fault or cross both fault systems. When stress on both faults accumulates simultaneously toward similarly high levels, it’s more likely that a large joint rupture will cross both systems, according to the study. The model showed that stress...