Tuesday, 9 April 2013

Ash eruption on Mount Yasur, Vanuatu.

The Yasur Volcano near Sulphur Bay on Tanna Island has begun a new cycle of volcanic activity according to the Vanuatu Department of Meteorology and Geohazards. The volcano, which is one of the most active volcanoes of the Pacific Ring of Fire, has been relatively quiet since July last year, began ash venting at about 3.15 pm local time on (4.15 am GMT) Tuesday 2 April 2013, then again at about 7.00 am on Friday 5 April (8.00 pm on 4 April GMT). Satellite images suggest the volcano began emitting gas on 1 April.

Ash venting from Mount Yasur in July 2009. Vanuatu Department of Meteorology and Geohazards.

Yasur is located on the southeastern part of Tanna Island. It is a small volcano, rising 365 m above sea level and 1500 m wide at the base, but very active with frequent ashfall type eruptions. It forms part of the 4 km wide Yenkahe Caldera, sitting on the base of the northeast flank of the older Tukosmeru Volcano. Yasur is not believed to be a very old volcano, though it has been erupting for at least 300 years (an eruption was recorded by Captain Cook). The Yenkahe Caldera is subject to both rapid uplift (about 20 m in the last century) and rapid erosion; most of the structures in the area are made of poorly consolidated ash, and the island receives frequent heavy rainfalls.

The islands of Vanuatu are located on the southwestern fringe of the Pacific Plate, close to the New Hebrides Trench, along which the Australian Plate is being subducted. As the Australian Plate sinks into the Earth it passes under the Pacific Plate, at the same time being partially melted by the friction and the heat of the planet's interior. Some of the melted material then rises through the overlying plate, fueling the Volcanoes of Vanuatu.


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