The Pacific tsunami warning centre said a widespread tsunami was possible for a number of Pacific nations, although not as far as New Zealand or Australia.
It said hazardous tsunami waves from the quake were possible within the next three hours along some coasts of Papua New Guinea, Solomon Islands, Nauru, Vanuatu, and Indonesia as well as Chuuk, Pohnpei and Kosrae in the Federated States of Micronesia.
The centre say any waves would be between 0.3m and 1m above tide level for the Solomons and Papua New Guinea, and less than 0.3m above normal tide levels elsewhere.
There were no immediate reports of casualties or damage.
Bougainville and the nearby Solomon Islands are in the Pacific's geologically active "Ring of Fire".
- Reuters / RNZ