Sydney: A shallow 6.0-magnitude earthquake hit off the coast of the South Pacific island of Vanuatu on Monday, the US Geological Survey said, but there was no tsunami warning issued.
The quake struck at a depth of just one kilometre (half a mile), around 61 kilometres southwest of the capital Port Vila.
"It was very shallow and produced a lot of surface water activity, but no tsunami," said a GeoScience Australia seismologist, adding that it would have been felt in Port Vila but damage was unlikely unless structures were weak.
It follows a series of recent quakes near Vanuatu including two of 7.0 magnitude or over in the past month.
"Over 40 quakes this year have been recorded in the area southwest of Port Vila and this would be an aftershock from those," said the seismologist.
Vanuatu lies on the so-called "Pacific Ring of Fire", a zone of frequent seismic activity caused by friction between shifting tectonic plates.