SUVA, July 22 (Xinhua) -- An earthquake with a magnitude of 6.0 jolted 90 km northeast of Norsup, Vanuatu, at 16:04 (0504 GMT) local time on Monday, the U.S. Geological Survey (USGS) said.
There were no immediate reports of casualty or damage.
The epicenter, with a depth of 10 km, was determined to be at 15.544 degrees south latitude and 168.043 degrees east longitude, according to the USGS.
The Pacific Tsunami Warning Center did not immediately issue a tsunami warning based on the quake.
Pacific island countries such as Fiji, Tonga and Vanuatu lie on the so-called Pacific "Ring of Fire," an arc of earthquake and volcanic zones where continental plates collide, producing frequent seismic activities. ■