The 1968 Borrego Mountain earthquake occurred in the evening hours of April 8, near the small unincorporated community of Ocotillo Wells in San Diego County. The moment magnitude 6.6 (7.0 on the surface wave magnitude scale) earthquake reached VII (Very strong) or IX (Violent) on the Mercalli intensity scale, causing some damage in the Imperial Valley, although no injuries or deaths had been reported. Shaking from this earthquake was felt over a wide area, even being reported in Las Vegas, Nevada, and parts of Arizona. This was the largest earthquake in Southern California since the 1952 Kern County earthquake 16 years prior.