A strong 6.4-magnitude earthquake struck off the the South Pacific island of Vanuatu on Sunday, seismologists said, but there were no immediate reports of damage and no tsunami warning was issued.
The quake struck at 11:54am (00.54GMT), 108 kilometres (67 miles) northwest of the capital Port Vila at a depth of 34 kilometres, the United States Geological Survey said.

Vanuatu lies on the so-called "Pacific Ring of Fire", a zone of frequent seismic activity caused by friction between shifting tectonic plates.

It has been rocked by several large quakes in recent years, averaging about three magnitude 7.0 or above incidents every year without any major damage.