Tuesday, May 10, 2011

Major Earthquake Hits Loyalty Islands

Magnitude 6.8 Earthquake
Loyalty Islands
May 10, 2011

GDACS Issues Green Tsunami Alert

A strong 7.1 magnitude earthquake (later downgraded to 6.8M) struck off the Pacific islands of Vanuatu and New Caledonia Tuesday, the U.S. Geological Survey said, but there were no immediate reports of damage and a local official said that a tsunami was not expected.

Nonetheless, the earthquake triggered a green tsunami alert by GDACS. A green alert means very limited chance on damage and/or injuries as a result of the waves generated.  No Pacific-wide Tsunami was expected by the Pacific Tsunami Warning Center (PTWC).

The Global Disaster Alert and Coordination System provides near real-time alerts about natural disasters around the world and tools to facilitate response coordination, including media monitoring, map catalogues and Virtual On-Site Operations Coordination Centre.

Location20.252°S, 168.273°E
Depth14.9 km (9.3 miles)
  • 131 km (81 miles) SW (232°) from Isangel, Vanuatu
  • 146 km (91 miles) NNE (16°) from Tadine, Loyalty Islands, New Caledonia
  • 278 km (173 miles) S (181°) from PORT-VILA, Vanuatu
  • 1748 km (1086 miles) ENE (66°) from Brisbane, Australia
Location Uncertaintyhorizontal +/- 13.2 km (8.2 miles); depth +/- 2.5 km (1.6 miles)
ParametersNST=534, Nph=553, Dmin=>999 km, Rmss=0.95 sec, Gp= 14°,
M-type="moment" magnitude from initial P wave (tsuboi method) (Mi/Mwp), Version=C
Event IDusc0003ag4 (click for details)

There have been several aftershocks in the Loyalty Islands so far with the largest to date being a 5.7M.  Several more aftershocks are expected, but they should

This earthquake is similar to the ones that occurred in December, 2010,  and again in January this year which occurred as the result of normal-faulting within the Australia plate, in the region of the boundary between the Australia plate and the Pacific plate. This is a very active region due to the stresses which occur where the Australia plate subducts beneath the Pacific plate at the New Hebrides trench.

General Tsunami Information

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