  Las Vegas Los Angeles San Diego Las Vegas  | |
| UTC time | 1968-04-09 02:28:58 |
|---|---|
| ISC event | 823631 |
| USGS-ANSS | ComCat |
| Local date | April 8, 1968 |
| Local time | 6:28 p.m. PST |
| Magnitude | 6.6 Mw |
| Depth | 11.1 km (6.9 mi) |
| Epicenter | 33°10′48″N 116°06′11″W / 33.180°N 116.103°W |
| Type | Strike-slip |
| Areas affected | Southern California |
| Total damage | Minor |
| Max. intensity | MMI VII (Very strong) |
| Casualties | None |
The 1968 Borrego Mountain earthquake occurred on April 8, at 18:28 PST in the geologically active Salton Trough of Southern California. The Salton Trough represents a pull-apart basin formed by movements along major faults. This region is dominated by major strike-slip faults one of them being the San Jacinto Fault which produced the 1968 earthquake. The mainshock's epicenter was 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). The zone of surface rupture was assigned a maximum Modified Mercalli intensity (MMI) of VII (Very strong).
Despite being the largest earthquake to strike California since the 1952 Kern County earthquake, structural damage was limited due to the region being sparsely populated. Damage mostly comprised fallen plaster from building facades and material losses. Rockfalls were widely reported in the epicenter region. There was also no deaths or injuries as a result Some minor damage also occurred in Arizona and Baja California. In the aftermath, many nearby faults displayed afterslip which became the subject of scientific interest.