The 1987 Whittier Narrows earthquake occurred in the southern San Gabriel Valley and surrounding communities of southern California at 7:42 a.m. (Pacific Daylight Time) on October 1, 1987. The magnitude 5.9 earthquake was originally assigned a magnitude of 6.1 but was revised downward a few days later when additional data became available. Its epicenter was in the town of Rosemead, several miles north of Whittier, had a relatively shallow depth of 9.5 kilometers (5.9 mi), and was felt as far as San Luis Obispo, San Diego, and Las Vegas.[3]