Hundreds of people ran into the streets in Talca in panic during the quake, which was felt for nearly a minute on Sunday.
In its first quake damage report, the Office of National Emergencies said one person was injured in a car accident in the Bio Bio region.
"For now we do not have reports of any fatalities. There is some evidence of people injured, unfortunately from pieces of walls that fell," Interior Minister Rodrigo Hinzpeter said.
Chilean news media reported electrical blackouts and broken phone lines in the area around Talca, 300km south of the capital, Santiago.
Some injuries were reported from falling debris in the interior of a Catholic church in Santiago.
"We were at mass when material started falling," a priest told the local media. "People became frightened and left."
The USGS initially reported the quake's magnitude as 7.2 but later downgraded it to 7.1.