
The US Geological Survey said the quake hit about 143 kilometres (88 miles) southeast of the capital Port Vila at 7:09am local time (2009 GMT Wednesday) at a depth of 200 kilometres.
The Hawaii-based Pacific Tsunami Warning Center said there was no tsunami threat from the quake.
A spokeswoman for Vanuatu's National Disaster Management Office said there were no immediate reports of damage.
"It was a strong magnitude earthquake but it was very deep. Because of that we're not expecting any destruction," she told AFP.
Vanuatu is part of the "Ring of Fire," a zone of tectonic activity around the Pacific frequently subject to earthquakes and volcanic eruptions.