A magnitude 6.4 undersea temblor occurred today between Vanuatu and New Caledonia, the U.S. Geological Survey, based in Denver (Colorado) said.

The quake occurred at 5:33 a.m. local time (18:33 Monday GMT). Its depth was estimated at 3.6 kilometers below sea level.

The epicenter was located some 85 kilometers South West of Tanna island (South Vanuatu) and 175 kilometers North-North-East off the island of Maré (part of New Caledonia's Loyalty islands group).

This temblor was followed by at least one aftershock in the same region, measuring 6.3 at 7:27 a.m.

The Pacific Tsunami Warning Center (PTWC) based in Pearl Harbor (Hawaii) has issued one single message at 18:47 GMT Monday for information only, but no alert.

"No destructive widespread tsunami threat exists based on historical earthquake and tsunami data. However, earthquakes of this size sometimes generate local tsunamis that can be destructive along coasts located within a hundred kilometers of the earthquake epicenter. Authorities in the region of the epicenter should be aware of this possibility and take appropriate action," the PTWC bulletin stated.

Earlier this month, between April 8 and 10, the same region, between Vanuatu and neighboring New Caledonia, was also the scene of an intense seismic activity at an average depth of 35 kilometers. This included one quake peaking 7.3 on the Richter scale.

In the French Pacific, the French government has recently announced it was stepping up detection and prevention systems for its three Pacific dependencies (New Caledonia, French Polynesia, Wallis and Futuna).

The implementation and installation of tsunami meters and wave height detection devices is currently under way with a particular focus on the most exposed islands in case of a tsunami generated near Tonga or Vanuatu, such as the Loyalty Islands and Wallis.

In New Caledonia's Melanesian region, authorities in the Solomon Islands have on April 2 commemorated the first anniversary of the April 2, 2007 disaster: a magnitude 8 earthquake that triggered a subsequent tsunami in the North of the archipelago, in the province of Gizo.

Over 50 persons died and thousand lost their homes as a result.