The 1968 Borrego Mountain earthquake occurred on April 8, at 6:28 p.m. PST, near the unincorporated community of Ocotillo Wells in San Diego County. The moment magnitude (Mw ) 6.6 strike-slip earthquake struck with a focal depth of 11.1 km (6.9 mi). Damage was relatively moderate, and the mainshock was assigned a maximum Modified Mercalli intensity (MMI) of VII (Very strong). Shaking was felt in Nevada, and Arizona. It was the largest earthquake to strike California since 1952, and its display of afterslip became the subject of scientific interest.