A series of earthquakes in the vicinity of Vanuatu Natural Disasters
In early February, the archipelago of Vanuatu have been several earthquakes. The first happened on January 31 and still had the power of 5.1 points and a depth of 172.5 km. February 2 was a strong earthquake in the 7.1-magnitude depth 23.1 km. It was followed by a few more: 5.3 points, the depth of 10 km, 5 points, the depth of 33.3 km, 5.5 points, depth of 22.8 km, 5.2 points, depth of 20.8 km, 5, 1 point, the depth of 31.9 km and 5.1 points, depth of 17.4 km.
Fig. 2. The recent seismic activity.
The cause of all earthquakes in the south-west Pacific was offset Australian lithospheric plate. Disaster epicenter was located 15 km west of Novogebridskoy depressions bathymetric boundary between the Australian and Pacific plates, where one plate lithospheric layer sags under the mantle of the other just below the northern part of the island of Fiji. Australian plate sinks beneath the Pacific at a rate of 84 mm per year, moving to the east-northeast.
Novogebridskaya basin reaches a depth of 7.600 meters and is the biggest fault in the entire Coral Sea. Length of cavity, the envelope south to northern Vanuatu Tonga Trench 1,200 km, width 70 km, area 84 000 km ².
Over the past 30 years in a specific region within 250 km have been about a dozen seven-point earthquake. But most of them are concentrated east Novogebridskoy depression. Earthquake of 7.3 magnitude that occurred on Christmas Day 2010, as well as the event on February 2, what happened to the west of the New Hebrides, only 225 km to the south.
Fig. 3. Location in the 7.1-magnitude earthquake.
Morning of 3 February was marked by seismic activity in the form of an earthquake in 6 points with an epicenter 21.7 km depth, located 116 km north-west of Port Villa, Fr. Efate, in 204 km south of Lugatnvillya about. Espirito Santo, and 318 km north-west of Isangel about. Tana, Vanuatu (17.376 ° S, 167.278 ° E).
Fig. 4. The intensity of the earthquake on the left — in the 7.1-magnitude on the right — in 6 points.