A powerful magnitude 7.1 earthquake has struck off Papua New Guinea, US officials said.
The US Geological Survey says the quake was measured at a depth of around 50 kilometres and was about 52 kilometres from the town of Panguna on Bougainville island.
A 6.7-magnitude aftershock has followed the quake off the island of Bougainville.
"They would have gotten a strong shake across the island, and there's the possibility of some damage," David Jepsen from Geoscience Australia said.
Residents in the northern town of Buka and the southern town of Buin say they felt the quake.
A local journalist says two water tanks have been damaged near Buin.
There have been no immediate reports of injuries or major damage.
Local tsunami warning
The Global Disaster and Coordination System has issued an alert for a small tsunami with a maximum height of 40 centimetres after the first quake.
While the Hawaii-based Pacific Tsunami Warning Centre has ruled out the threat of a Pacific-wide destructive tsunami, Mr Jepsen says there is a possibility of a local tsunami in PNG.
He says the depth of the quake could not be accurately defined except that it was under 50 kilometres.
"If it's really shallow like 10 (kilometres deep), there's more possibility of (local) tsunami," he said.