At 7:42 a.m. on October 1, 1987, a magnitude 5.9 earthquake, centered in the San Gabriel Valley city of Rosemead, jolted the region as the first major temblor felt in Southern California in nearly a generation.
Eight lives were lost, several hundred were injured, and some 10,000 structures were damaged, costing an estimated $358 million. The quake originated from a previously unmapped blind thrust fault, now part of the Puente Hills fault system.
The quake, which struck as commuters were heading to work and students were arriving at school, caused extensive damage to older unreinforced masonry buildings in historic downtown Whittier and closed the 5/605 freeway interchange near Santa Fe Springs as cracks and fallen chunks of concrete were discovered on the roadway. The quake was felt as far away as Las Vegas, San Diego, and San Luis Obispo, but the most heavily-damaged areas were located in the San Gabriel Valley and in northern Orange County. The campus of California State University Los Angeles in L.A.'s El Sereno neighborhood experienced extensive damage to its library, and a panel of fallen concrete in a campus parking structure claimed the life of a student. A Southern California Edison worker also lost his life in the San Gabriel Mountains while working in an underground construction hole.
The Whittier Narrows Earthquake caused many buildings in Southern California, particularly brick and masonry structures, to undergo seismic retrofitting procedures in the years following the quake.