New Zealand Volcanoes

The White Island Volcano in New Zealand is an active Stratovolcano that is 70% under water.

One of the most interesting volcanoes in New Zealand is the White Island Volcano. This particular volcano has been active for at least 150,000 years; and for the last 40 years it is known as the most active volcano in New Zealand. This volcano is considered a composite cone volcano, because it’s built from multiple eruptions throughout thousands of years forming composite cones out of layers of andesite lava flows and pyroclastic deposits (tephra). “Although andesitic composite cones are built mostly of fragmental debris, some of the magma intrudes fractures within the cones to form dike or sills. In this way, multiple intrusive events build a structural framework of dikes and sills that knits together the voluminous accumulation of volcanic rubble.” (http://volcanology.geol.ucsb.edu/volcano.htm)

Basic illustration of how a Composite Volcano is formed.

 “Andesite magma can generate strong explosive eruptions to form pyroclastic flows and surges and enormous eruption columns”. (http://volcano-pictures.info/glossary/andesite.html) Later, andesite turns into a grey to black volcanic rock.

But what really makes this volcano interesting is that 70% of this Stratovolcano is submerged under the sea. It was formed by the subduction of the Pacific Plate below the Australian Plate. With the help of a few cameras on the island, the country is able to monitor the active volcano and keep an eye out for the occasional ash, gas, and lava bombs. A lava bomb is a mass of molten rock that is ejected from the volcano during eruption.

The gas this volcano produces is actually very bad for human contact because it’s a mix of carbon dioxide and sulphur dioxide. When they mix, “the gasses dissolve in the magma escape and rise towards the surface where they mix with, and heat the groundwater beneath the crater floor.” (http://www.gns.cri.nz/Home/Learning/Science-Topics/Volcanoes/New-Zealand-Volcanoes/White-Island) When this happens, a white steam forms above White Island. Otherwise known as an acidic cloud that can sting the eyes and skin and affect your breathing.

In order for you to visit the volcano, they require you to wear a gas mask because of the toxic gas it produces.

http://ebrondoherty.files.wordpress.com/2013/02/wi19.jpg