There was no initial reports of casualties or damage, but media reports said the quake was felt in a wide area of central Chile, where some residents evacuated coastal areas as a precaution.
The US Geological Survey and Chile`s National Emergency Office (ONEMI) said the quake occurred in the Pacific some 70 kilometers (45 kilometers) from the city of Concepcion.
The USGS initially reported a major 7.0 magnitude, and later revised that to 6.8, which can still cause devastation.
The quake struck at 2005 GMT near a region in central Chile that was heavily damaged by an 8.8 magnitude earthquake and tsunami on February 27, 2010.
Rodrigo Ubilla, an Interior ministry official, said that there were no casualties or damage to buildings reported and praised the "exemplary" reaction of the population, saying the people showed "maturity" after last year`s catastrophe.
Last year`s disaster led to more than 500 deaths and $30 billion dollars in damage, and led to an inquiry over the lack of a timely tsunami warning.
ONEMI director Vicente Nunez said "people reacted with concern," because the incident occurred near the anniversary date of the tsunami, and urged people to return to their homes.
The Pacific Tsunami Warning Center said that "a destructive Pacific-wide tsunami is not expected," from this quake but that earthquakes of this size "sometimes generate local tsunamis that can be destructive along coasts" within a 100 kilometers of the epicenter.
"Authorities in the region of the epicenter should be aware of this possibility and take appropriate action," it said.
A spokesman for Chile`s emergency office said of the latest quake, at a depth of 14.8 kilometers, "does not have the characteristics to create a tsunami."
The USGS said the location of the earthquake was 395 kilometers (245 miles) southwest of Santiago.