The quake was felt strongly in the resort city, as well as in Mexico's capital, but there were no immediate reports of injuries. Minimal damage occurred in mostly old buildings that were not retrofitted.
The quake's center was 30 miles deep, according the USGS. The quake struck at 7:27 a.m. about 164 miles southwest of Mexico City, which shook for at least 30 seconds. Buildings swayed as people fled high rises and took to the streets.
Caltech professor Doug Given said many were able to evacuate before the strongest shaking.
"Because of the earthquake early-warning (system), they had advanced notice that the ground was about to move," Given said.
The earthquake was first reported as a 7.5, but USGS later downgraded it to a 7.2 magnitude.
Mexico is one of the world's most seismically active regions, as it's located on three large tectonic plates.
The Associated Press contributed to this report.
