A hospital was evacuated but there have been no reports of damage so far after a 7.9 earthquake struck Papua New Guinea just before midnight NZT.
The earthquake struck about 50km east of Taron, at a depth of 103km.
The Pacific Tsunami Warning Centre warned hazardous waves were possible in the Pacific but said later in the early hours of the morning that the tsunami threat had ended.
It had said waves reaching 1-3m above the tide level were possible in coastal areas of Papua New Guinea for several hours.
The Geophysical Observatory, in PNG capital Port Moresby, said a tsunami smaller than 1m hit the coast of the island of New Ireland shortly after the earthquake.
Waves of less than 0.3m above the tide level were forecast for other areas of the Pacific, including Indonesia, Solomon Islands, Nauru and Vanuatu.
Waves of less than a metre in height were observed at Tarekukure Wharf in Solomon Islands.
New Zealand's Civil Defence at first issued a tsunami warning for the whole of the country, but that was cancelled about 1.30am after analysis of the seismic data.
Australia's Bureau of Meteorology said there was no threat to its coastlines.
'I was thinking the ground would break open'
Many residents in the northern parts of the autonomous region of Bougainville sought higher ground amid warnings that tsunami waves were possible.
A nurse at the Buka General Hospital in Bougainville, Tracey Anunfi, said the patients at the hospital's four wards were taken to higher ground, and stayed there all night.
"All of us, including the hospital and everyone down at the town area, we all managed to move up. There's higher ground, it's at Hahela, we managed to get there and all of us went into the cathedral there."
Ms Anunfi said nurses brought medication to the church for the patients, who had since returned to the hospital.
She said the quake was ferocious.
"It was scary, it was frightening - first of its kind - because it shook and it lasted for some minutes.
"I was standing outside and I could feel the ground shaking and swaying ... the ground was moving. I just stood there and was looking at the buildings and power poles, thinking that they might fall down. I was thinking the ground would break open."
Residents in other parts of Papua New Guinea, including Port Moresby and Kavieng in the northern tip of New Ireland, said they had not felt the quake, and no evacuation plans were in place.
An aid worker with Plan International tweeted that it was felt very strongly on Buka Island, where the charity has staff, but there were no reports of damage or casualties there.
- RNZ / Reuters