The earthquake ruptured a substantial portion of the southern San Andreas fault, but not the entire length. Thomas H. Jordan, director of the Southern California Earthquake Center, stated that the slip likely stopped in the area near Cajon Pass, perhaps because the tectonic stresses on that part of the fault had been released several decades earlier during the 1812 Wrightwood earthquake. The average slip along the fault was , and a maximum offset of was recorded in the Carrizo Plain area in southeastern San Luis Obispo County. With an estimated magnitude of 7.9, this was the last "Big One" in Southern California. The extreme southernmost portion of the San Andreas fault, which terminates near Bombay Beach at the Salton Sea, last ruptured in 1680.