A powerful magnitude 6.8 earthquake has shaken the coast of Chile, swaying buildings in the capital of Santiago. There are no immediate reports of damage.

The U.S. Geological Survey says the quake hit at 10:57 a.m. local time (1557 GMT) and was centered 66 kilometers (40 miles) west-southwest of the city of Constitucion. The epicenter was 16.5 kilometers (10.3 miles) below the surface.

Chile's national emergency agency says the quake was felt across a broad swath of the central and south of the country.

The USGS initially calculated the magnitude at 7.2.

Chile, located on the Pacific "Ring of Fire," has a long history of deadly quakes, including an 8.8-magnitude quake in 2010 off the south-central coast that triggered a tsunami that devastated coastal towns.