Several aftershocks have been felt in the region while a tsunami warning has been issued for the coastal areas of Papua New Guinea, the Solomon Islands, Indonesia, Nauru and other islands in the vicinity.
A magnitude 7.9 earthquake struck off the coast of Papua New Guinea on Saturday, the US Geological Survey reported.
The epicentre of the quake was located 157 kilometres east of Rabual a depth of 103.2 kilometres at 10:51 GMT.
Several aftershocks were felt in the region while a tsunami warning has also been issued by the Pacific Tsunami Warning Centre (PTWC).
Hazardous tsunami waves could hit coastal areas of Papua New Guinea, the Solomon Islands, Indonesia, Nauru and other islands in the three hours following the quake, the PTWC said.
New Zealand also issued a tsunami warning which it later cancelled. Meanwhile, Hawaii and Australia said there was no threat to their coastlines.
"We're continuing to assess the situation ... at this stage we are advising New Zealanders to stay off the beaches, stay out of the water, not to go sightseeing and to listen to the radio and TV," a spokesperson for the Ministry of Civil Defence & Emergency Management said.
There were no immediate reports of damage or casualties from the quake, which the USGS initially measured at magnitude 8 and at a depth of 73 kms.
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.