A magnitude 8.3 earthquake hit off the coast of Chile on Wednesday, shaking buildings in the capital city of Santiago and generating a tsunami warning for Chile and Peru.
Chile's government urged residents to evacuate the coastline. There were no immediate reports of injuries or damage.
Reuters witnesses said the quake was felt as far away as the Argentine capital, Buenos Aires, on the eastern seaboard of South America.
The quake struck 105 miles (169 km) north of Valparaiso and was originally reported as magnitude 7.9, the US Geological Survey said.
Hazardous tsunami waves from the quake were possible along the coasts of Chile and Peru within the next several hours, the Pacific Tsunami Warning Center said. A tsunami watch was also issued for Hawaii.
If tsunami waves impact Hawaii, the estimated earliest arrival time would be 3:06 a.m. Hawaii Standard Time (1306 GMT) on Thursday, the Pacific Tsunami Warning Center said.
The quake struck at a depth of 15.5 miles (25 km), the USGS said.
Less than an hour after the initial earthquake, three aftershocks all greater than magnitudes 6.1 struck the region, USGS reported.
Chile's state copper miner Codelco said workers at its Ventanas division have been evacuated.