The Elsinore Fault Zone stretches roughly 180 kilometres across Southern California, running northwest to southeast from the Santa Ana Mountains down toward the Mexican border, where it links to the Laguna Salada Fault. It is a right-lateral strike-slip fault and one of the major members of the San Andreas system, accommodating part of the Pacific–North American plate motion.
Despite its size, the Elsinore is one of the quieter large faults in the region, slipping at a relatively slow rate of a few millimetres per year and producing fewer felt earthquakes than the nearby San Jacinto. Geologists nonetheless consider it fully capable of a magnitude 6.5 to 7 rupture, and its long recurrence intervals mean strain may be building without frequent release.
Historically it produced a magnitude 6 earthquake in 1910 near Lake Elsinore, its most notable modern event. Because the fault passes beneath rapidly expanding communities in Riverside and San Diego counties, it is regarded as a significant, if under-recognised, seismic hazard for inland Southern California.