NOUMEA, New Caledonia - A tsunami alert and emergency evacuations were triggered in New Caledonia after a powerful magnitude 7.6 earthquake shook the French territory in the South Pacific.

The U.S. Pacific Tsunami Warning Centre said in a statement that the powerful undersea earthquake off the coast of the Pacific island of New Caledonia on Wednesday triggered a tsunami alert.

It said that the quake was shallow 10 km (6 miles) deep and its epicentre was 168 km east-south-east of Tadine town, which is one of New Caledonia's Loyalty Islands.

Soon after the earthquake, the Hawaii-based Pacific Tsunami Warning Centre said, "Tsunami waves reaching 1 to 3 metres above the tide level are possible along some coasts of New Caledonia and Vanuatu."

It also warned of the possibility of waves of up to 1 metre (3 feet) along some coasts of Fiji.

The agency warned that some areas might register sea level fluctuations of up to 30 cm in the hours after the earthquake.

Subsequently, New Caledonian authorities ordered the immediate evacuation across a swathe of the South Pacific, with urgent text messages being sent out to all the 270,000 residents in the French Territory.

The messages sent by the emergency warning systems directed residents to go to refuges immediately.

In a statement, the Office of the High Commissioner of the Republic of France in New Caledonia urged people to regroup at shelter sites with essentials like medicines and water.

However, local authorities noted that there were no immediate reports of major damage or injuries from the quake.

In a statement, Basile Citre, a municipal official on the Loyalty Island of Mare, said that he had convened a meeting at the town hall following the tremor and a bigger aftershock.

Citre said, When the sirens sounded, the population headed for higher ground for safety. For now, nothing serious has happened."

Meanwhile, the Vanuatu Geohazards Observatory noted that the Tanna Island, which is sparsely populated was expected to be most affected.

However, a spokesperson for the Observatory said that no evacuations had been ordered there, adding, There are no sirens on Tanna but the people on the island are familiar with these situations and they will have taken precautions and gone to higher ground."

Threat passes despite strong aftershocks

Authorities said that the quake was followed by at least ten strong aftershocks of up to magnitude 6.6, which were centered about 170 km southeast of New Caledonias Loyalty Islands.

People living in areas along the coast noted that the initial quake shook the walls of buildings and even turned the sea foamy in some areas.

The French mining and metals group Eramet, which operates the Doniambo nickel plant in the main harbour of Noumea, said it had enacted its tsunami alert process.

A spokesperson for Eramet said that people had felt the quake, which was strong but cause long-lasting shaking.

He said, "The procedure is to ask people who work near the sea to move higher up."

Later in the day, the Pacific Tsunami Warning Centre said that waves measured by its monitors around the region reached only reached about 72 cm.

Further the Noumea Civil Defence said that while tsunami waves hit parts of the Loyalty Islands and the Isle of Pines, no damage was caused.

A spokesperson for the Civil Defence department said, "Reports from the area confirm that the strength of the tsunami has fallen significantly and there is no longer a major risk for the population."

Three hours after issuing the alert, the Pacific Tsunami Warning Center issued a statement saying the threat stemming from the initial quake has now passed."

New Caledonia in South Pacific is part of the geological disaster zone in the Pacific called the Ring of Fire, which has seismically active tectonic plates.

The series of fragile fault lines that form the Ring of Fire stretch 25,000 miles from New Zealand, across the east coast of Asia through Indonesia, the Philippines and Japan, over to Alaska, Canada and the U.S. West Coast then down to the southern tip of South America.

Overall, the Ring of Fire contains 452 volcanoes and several tectonic plates in the earths crust and more than half of the worlds active volcanoes above sea level are part of the ring.