The quake, which initially registered as 6.5 in magnitude, hit 4.8 miles south of El Encanto and 11.9 miles northeast of Tapachula in the southern state of Chiapas around 8:14 a.m. PT, USGS said.
The temblor caused tall buildings to sway hundreds of miles away in Mexico City, where some people were evacuated from offices along a central boulevard.
There were no immediate reports of injuries.
Experts at the USC Earthquake Center said it's a reminder for people to be prepared for large earthquakes.
The Associated Press contributed to this report.