Flights to and from New Zealand have been disrupted following an eruption on Hunga Ha’apai, a submarine volcano in Tonga, on Monday 12 December 2015, producing an ash column 4500 m high and discolouring the sea red with ash, according to the Wellington Volcanic Ash Advisory Centre. The volcano is reported to have become active on 20 December 2014, according to the Institute of Geological & Nuclear Science in New Zealand, but this is the first major disruption caused by the volcano this year. The crater of Hunga Ha’apai lies beneath the sea, but two small islands, Hunga Tonga and Hunga Ha’apai, which form part of the crater rim, reach 149 m and 128 m above the sea respectively.
The ash coloumn over Hunga Ha'apai on 13 January 2014. Radio Live/Twitter.
Hunga Ha’apai ies on the Tonga/Kermadec Ridge, and is fed by the subduction of the Pacific Plate beneath the Australian
Plate along the Kermadec/Tonga Trench. As the Pacific Plate sinks into
the Earth it is warmed by a combination of heat from friction with the
overlying Australian Plate, and heat from the planets interior. This
leads to partial melting of the Pacific Plate, with some of the melted
material rising through the overlying Australian Plate as magma, fuelling
the volcanos of the Kermadec/Tonga Ridge.
Diagram showing subduction along the Tonga Trench, and how this feeds the volcanoes of the Tonga Volcanic Arc. York University.
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