On Saturday 3 March 2012 at about 23.20 local time (12.20 GMT) the French Overseas Territory of New Caledonia was hit by an Earthquake roughly 175 km southeast of the Loyalty Islands. The quake was measured as 6.6 on the Richer Scale at a depth of 15.2 km by the United States Geological Survey and 6.7 on the Richter Scale at a depth of 46 km by Geoscience Australia. No tsunami warning has been issued and it is unlikely that there will be any serious damage or casualties, but the quake was probably felt from some of the neighboring islands.
Map showing the location of the quake, and the areas where it might have been felt. United States Geological Survey.
The Loyalty Islands are an island arc sitting above the New Hebrides Trench. The New Hebrides Plate is being subducted beneath the Australian Plate in the trench. As it sinks below the Australian Plate it creates friction, which is felt as Earthquakes. Such plate margins are typically associated with volcanic activity, as material from the subducted plate melts and rises up through the overlying plates as magma, forming volcanoes at the surface. The Loyalty Islands are volcanic in origin, but do not have any current volcanoes, indeed the islands are quite ancient by volcanic island standards, with some rocks dated to the Permian (225-280 million years ago.
See also Possible eruption on Tinakula, Series of Earthquakes shakes Vanuatu, Ash cloud reported over Karkar Island, north of Papua New Guinea, Earthquake in Vanuatu, 21 August 2011 and Earthquakes on Sciency Thoughts YouTube.