Pacific nations have been on a high alert of tsunami triggered by the strong quake, but China's National Marine Environmental Forecasting Center said it might not affect Chinese coast due to the long distance.
The earthquake occurred at 2:34 p.m. (Beijing Time) in Chile. The epicenter was 35.8 degrees south latitude and 72.7 degrees west longitude, with a depth of 33 kilometers, said a statement from the CEA.
In an earlier report, the CEA survey put the magnitude of the earthquake at 8.5.
The location was about 100 km north to Chile's second largest city Concepcion and 320 km south to Chilean capital Santiago, it said.
Areas within 200 km of the epicenter have experienced a number of earthquakes, among which an 8.3-magnitude quake in 1939 killed 28,000 people, said the CEA.
About 400 km southwest to the epicenter, an 8.9-magnitude quake in 1960 claimed about 20,000 lives and triggered a tsunami that swept across the Pacific Ocean, killing scores of people in Japan and the Philippines.
The statement said the CEA is closely following the development of the situation there.
The National Marine Environmental Forecasting Center said a wave about 1.8 meters high has been detected along the Chilean coast, 85 km from the epicenter, at about 5 p.m. (Beijing Time).