New Zealand's newest and most active volcano, Mt Ngauruhoe in the Taupo Volcanic Zone, produced andesite flows in 19, and avalanche deposits in 1975.
North-northeast-trending normal faults with throws up to 30 m cut the volcanoes within the graben.
Though not as well publicised as its neighbor, Mt Ruapehu (about 12 km to the south), Ngauruhoe is an imposing, almost perfect cone that rises more than 1,000 m above the surrounding landscape.
Eruptions from a central 400 m diameter crater have constructed the steep (33-), outer slopes of the cone [46, 97].
The shaded area is the andesite arc, and the inset shows the major components of the boundary between the Australian and Pacific Plates in the New Zealand region (arrows indicate relative motions).
Solid triangles are basalt-andesite volcanoes . Most vents lie close to the axis of a large graben in which Quaternary volcanic rocks overlie a basement of Mesozoic greywacke and Tertiary sediments [41, 69].