Cajon Pass sits between the San Bernardino and San Gabriel mountains in Southern California. A fault-driven transit route, it links inland valleys and the metro area with freight and road corridors, shaped by the San Andreas fault. Currently highlighted by seismic risk concerns tied to nearby fault networks.
Recent studies show California’s San Andreas and San Jacinto faults are under stress at levels not seen in a millennium, raising the risk of a large, multi-fault rupture. Cajon Pass could act as a bridge or barrier, and preparedness measures are urged as hazard models improve with physics-based simulations.