The Coalinga earthquake occurred on May 2, 1983, at exactly 23:42 UTC in Coalinga, California. The earthquake recorded 6.5 on the Richter scale. The earthquake was occasioned by creep along the San Andreas Fault. The Coalinga earthquake was felt from the Los Angeles area north to Susanville (Lassen County) and from the coast east to western Nevada. Through July 31, more than 5,000 aftershocks were recorded, of which 894 had a magnitude of 2.5 or larger. Most of the larger magnitude shocks were felt in Coalinga.
The Coalinga earthquake was caused by an 0.5-meter uplift of the anticline ridge northeast of Coalinga, but surface faulting was not observed. Ground and aerial searches immediately after the earthquake revealed ground cracks and fissures within about 10 kilometers of the instrumental epicenter, none of which appeared to represent movement on deeply rooted fault structures. About five weeks later, on June 11, however, an aftershock caused surface faulting about 12 kilometers northwest of Coalinga. (Full article...)