A spokesman for French mining group Eramet, which has a nickel plant in the harbour of Noumea, New Caledonia, said it triggered its emergency tsunami warning process.
According to the US Geological Survey, the quake struck about 104 miles east of Tadine at a shallow depth of six miles, followed by at least five aftershocks ranging in magnitude from 5.6 to 6.0.
A major natural disaster Tuesday night struck the territory of New Caledonia, sparking tsunami alerts.
New Caledonia, a French overseas territory, has a population of about 259,000.
Mr Rene said so far there were no reports of a tsunami or damage in the Loyalty islands.
New Zealand Civil Defence has just issued a statement saying there is NO TSUNAMI THREAT TO NEW ZEALAND.
New Caledonia's largest recorded quake was magnitude 8.1, in September 1920.
But the centre later reported waves measured by its monitors around the region only reached about 72 centimetres (2.4 feet) on the island of Tanna, Vanuatu.
The warning centre said there was no threat to Hawaii.
McGarry said he felt the quake where he is based in Vanuatu's capital, Port Vila, as a mild shaking.
According to Geoscience Australia, the quake struck southeast of the Loyalty Islands about 3:18pm AEDT, just four minutes after a magnitude 5.7 quake hit the area.
"We get a lot of earthquakes every year", he said.
Last month, the territory's 280,000 residents voted in a referendum to remain part of France.