A shallow 7.5-magnitude earthquake struck off the east coast of the Pacific islands of New Caledonia at 0418 GMT on Wednesday. 

The underwater earthquake was 10 kilometers deep, said the U.S. Geological Survey (USGS).

A tsunami warning has been issued within 1,000 kilometers of the epicenter, according to the Pacific Tsunami Warning Center (PTWC).

"Tsunami waves reaching one to three meters above the tide level are possible along some coasts of New Caledonia and Vanuatu," the PTWC said, adding that waves of up to one meter are possible for some coasts of Fiji.

There were no immediate reports of damage from the initial earthquake, which was followed by several strong aftershocks, with strongest registered at a magnitude of 5.9. 

New Caledonia sits on the Pacific "Ring of Fire," the arc of seismic faults around the Pacific Ocean where most of the world's earthquakes and volcanic activity occur.