The quake struck at 4:38 a.m. (12.38 p.m. ET Thursday) at a depth of 40 km (25 miles), the U.S. Geological Survey said. It was initially reported to be of magnitude 8.0.
There were no immediate reports of damage or casualties.
"Hazardous tsunami waves from this earthquake are possible within the next three hours along some coasts of Solomon Islands, Vanuatu, Papua New Guinea, Nauru, New Caledonia, Tuvalu and Kosrae," the U.S.-based Pacific Tsunami Warning Center (PTWC) said.
But PTWC canceled an initial tsunami watch alert for Hawaii.
"Based on all available data, there is no tsunami threat to the state of Hawaii," the PTWC said.
Australian authorities also said there was no risk to its coastlines, while the New Zealand Civil Defence office said it was evaluating the threat.
Calls to emergency services officials in the Solomons and Vanuatu rang out.
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