From the beginning on time, volcanoes have shaped the islands of New Zealand. New Zealanders have come to regard volcanoes as a national treasure and an inspiration, as much a vitlal part of a uniquely New Zealand way of life as they are a fiery force in its landscape.
New Zealand is one of the most tectonically active countries in the world. The Islands active volcanoes are within the Taupo Volcanic Zone, caused by the subduction of the Pacific Plate beneath the Australian Plate. The Pacific Plate is sinking beneath the Australian Plate at a rate of 5cms/year. The TVZ is an extensional feature called a back arc basin which allows magma from the mantel to well up near the crust causing more activity. The basin has formed to the east of the subduction zone and is caused by the extension of crust above the subduction zone. The extension has created two types of volcanism: Dacitic/Andesitic/Basaltic traditional cone volcanoes and Rhyolitic Calderas which have produced over 90% of the volcanic material. The TVZ extends from the centre of North Island from Ruapehu to White of Plenty and has been active for the last 1.6 million years. Unlike the North Island the Southn Island has no active volcanoes because its boundary is not subduction but is a conservative or strike slip boundary where the plates slide past each other.
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