Hawaii is under a tsunami watch after an 8.3-magnitude earthquake off the coast of north Chile.
The Pacific Tsunami Warning Centre issued the watch, saying a tsunami may have been generated by Wednesday's earthquake.
If there is a tsunami, the centre estimates that the first wave will arrive about 3am local time Thursday (0900 AEST Friday).
The powerful earthquake shook Chile's capital, causing buildings to sway and people to take refuge in the streets.
Several strong aftershocks hit within minutes as tsunami alarms sounded in the nearby port of Valparaiso. There were no immediate reports on any injuries or damage.
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The US Geological Survey initially reported the quake at a preliminary magnitude of 7.9, but it quickly revised the reading upward to 8.3.
A watch means that a tsunami is possible, but it doesn't mean it will happen, said Chevy Chevalier, a meteorologist with the National Weather Service in Honolulu.
"A watch is for everybody to be aware of it, that it's a possibility," he said.
"A warning means it's happening right now or it's imminent."
A tsunami warning was last issued for Hawaii in 2012, after a powerful earthquake off the coast of Canada.
The Pacific Tsunami Warning Centre lifted its tsunami advisory three hours after downgrading from a warning and less than six hours after the waves first hit the islands.
The state was spared from severe surges.
The Hawaii Emergency Management Agency said state officials are standing by, awaiting updates from the warning centre.
