A view of the bay of Noumea, the capital of New Caledonia, seen earlier this year.
Earthquakes generally have more destructive potential when the epicentre is near the surface and New Caledonia also sits on the Pacific Ring of Fire, where most of the world's earthquakes and volcanic activity occur.
Waves between one and three feet above the tide level are possible along the coast of Fiji.
The Pacific Tsunami Warning Center said that a magnitude 7.6 quake may threaten Noumea with unsafe waves Wednesday afternoon local time.
A second powerful quake, of magnitude 7, has hit off New Caledonia, just hours after one measuring 7.6, according to the Pacific Tsunami Warning Center (PTWC).More news: Highest-Paid YouTube Star Is 7 Years Old
A powerful 7.6 magnitude quake was registered off the east coast of New Caledonia in the South Pacific on Wednesday, the Pacific Tsunami Warning Center said.
Authorities said the quake, followed by at least 10 strong aftershocks, was centred about 170 kilometres (100 miles) southeast of New Caledonia´s Loyalty Islands at a depth of just 10 kilometres. But an automated assessment of the threat posed by the quake, generated by the US Geological Service, places the prospect of economic loss and fatality as very low.
Those living in threatened coastal areas were warned to "stay alert for information".
"The procedure is to ask people who work near the sea to move higher up".
It lies on the Pacific Ring of Fire, a horseshoe-shaped band of volcanoes and fault zones stretching from Alaska around the Pacific to Russian Federation.
Its citizens last month rejected independence in a referendum, though the vote revealed lower-then-expected support for remaining part of France.