WELLINGTON, Nov. 7 (Xinhua) -- An earthquake measuring 6.4 on the Richter scale struck the sea off the South Pacific island country of Vanuatu on Friday, the U.S. Geological Survey reported.

    There were no immediate reports of casualties or damages.

    The quake, occurred at 08:19 p.m. New Zealand time (0719 GMT Friday), was centered 320 km north of the Vanuatu capital of Port Vila, at a depth of 35 km.

    No tsunami warning was issued by the Hawaii-based Pacific Tsunami Warning center.

    Vanuatu is part of the Pacific "ring of fire" - an arc of earthquake and volcanic zones stretching from Chile in South America through Alaska and down through Vanuatu to Tonga in the South Pacific.