A fourth earthquake has struck off Papua New Guinea, the US Geological Survey says.
The magnitude 6.1 earthquake follows a powerful magnitude of 7.5 in the area on Saturday night, which sparked a tsunami warning for PNG and the Solomon Islands.
The Hawaii-based Pacific Tsunami Warning Center later cancelled the alert.
The latest earthquake struck 96km southwest of the town of Panguna on Bougainville at a depth of 18 kilometres at 10.30am (AEST) on Sunday, USGS said.
A 5.6-magnitude quake hit the same area on Saturday night at a depth of 69 kilometres, after a 6.6-magnitude tremor on Saturday morning.