The quake was recorded at 11 minutes after midnight (local and EST; 0511 GMT), nine miles (15 kilometers) from the city of Ica, which was badly damaged by a major 8.0 earthquake in August 2007 and also suffered damage in a quake last October.
Monday's quake was at a depth of 24.4 miles (39.2 kilometers). USGS maps showed the epicenter exactly on the Pacific Ocean coastline.
There were no immediate reports of damage or injuries. No tsunami warning was issued