Powerful 7.9 magnitude quake strikes off Papua New Guinea

A 7.9 magnitude earthquake struck off Papua New Guinea on Sunday, triggering a tsunami alert for several Pacific islands that was subsequently updated to cover just PNG and the neighbouring Solomon Islands.

The United States Geological Survey (USGS) measured the quake, some 47 kilometres (29 miles) west of Arawa on the north coast of Bougainville island, and the depth was put at 154 km (96 miles). It revised the quake's magnitude down from an earlier estimate of 8.0.

The Pacific Tsunami Warning Center said in an updated advisory that waves of 0.3 to one metre above tidal level were possible along the coasts of PNG and the Solomons. It wound back an earlier alert that encompassed Nauru, Pohnpei, Kosrae, Vanuatu, Chuuk and Indonesia.

Quakes are common in Papua New Guinea, which sits on the Pacific's "Ring of Fire," a hotspot for seismic activity due to friction between tectonic plates.

"Because of the great depth of the earthquake it is unlikely that there will be any significant tsunami activity," Chris McKee, assistant director at PNG's Geophysical Observatory Office in Port Moresby said.

McKee said there were no reports of damage from the epicentre of the quake, which is sparsely populated.

Australia and New Zealand both said they had assessed the threat and there was no danger to their coastlines.

Bougainville Island is one of the islands that make up the Autonomous Region of Bougainville within Papua New Guinea (PNG) which is home to around 300,000 people.