A strong 6.0 magnitude quake hit off the South Pacific island of Vanuatu today, the US Geological Survey said, one day after a shallow 6.9 tremor hit the country.
The latest quake was at a depth of about 21 kilometres and some 116 kilometres west-northwest of the capital Port Vila.
There were no immediate reports of casualties or damage from either quake and Geoscience Australia said there was unlikely to be any.
Seismologist David Jepsen said Vanuatu had been rocked by several large quakes in recent years, averaging about three of magnitude 7.0 or above a year, without suffering major damage.
"Magnitude 7.0 earthquakes occur there quite frequently... and there hasn't been much come out of that. There hasn't been any real reports of damage," Jepsen told AFP.
Vanuatu lies on the so-called "Pacific Ring of Fire", a zone of frequent seismic activity caused by friction between shifting tectonic plates.
The Hawaii-based Pacific Tsunami Warning Center issued an information bulletin but no alert on the 6.9 quake, saying "no destructive widespread tsunami threat exists based on historical earthquake and tsunami data".