Taupo Volcanic Zone facts for kids

Kids Encyclopedia Facts
MountNgauruhoe
Mount Ngauruhoe
Lake taupo landsat
Satellite photo of the Lake Taupo caldera
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Volcano and lake/caldera locations in the Taupo Volcanic Zone. The distance between the town of Rotorua and the town of Taupo is 80 km. (White Island is not shown.)

The Taupo Volcanic Zone (TVZ) is a volcanic area in the North Island of New Zealand that has been active for the past two million years and is still highly active. Mount Ruapehu marks its south-western end and the zone runs north-eastward through the Taupo and Rotorua areas and offshore into the Bay of Plenty. It is part of the larger Central Volcanic Region that extends further westward through the western Bay of Plenty to the eastern side of the Coromandel Peninsula and has been active for four million years. The Taupo Volcanic Zone is widening east–west at the rate of about 8 mm per year. It is named after Lake Taupo, the flooded caldera of the largest volcano in the zone, the Taupo Volcano.

Activity

There are numerous volcanic vents and geothermal fields in the zone, with Mount Ruapehu, Mount Ngauruhoe and White Island erupting most frequently. The zone's largest eruption since the arrival of Europeans was that of Mount Tarawera in 1886, which killed over 100 people. Early Maori would also have been affected by the much larger Kaharoa eruption from Tarawera around 1300 AD.

The last major eruption from Lake Taupo, the Hatepe eruption, occurred in 232 AD. It is believed to have first emptied the lake then followed that feat with a pyroclastic flow that covered about 20,000 square kilometres (7,722 sq mi) of land with volcanic ash. A total of 120 km3 (29 cu mi) of material is believed to have been ejected, and over 30 km3 (7.2 cu mi) of material is estimated to have been ejected in just a few minutes. The date of this activity was previously thought to be 186AD as the ash expulsion was thought to be sufficiently large to turn the sky red over Rome and China (as documented in Hou Han Shu), but this has since been disproven.

Taupo erupted an estimated 1,170 km3 (280 cu mi) of material in its Oruanui eruption 26,500 years ago. This was Earth's most recent eruption reaching VEI-8, the highest level on the Volcanic Explosivity Index.

The Rotorua caldera has been dormant longer, with its main eruption occurring about 240,000 years ago, although lava dome extrusion has occurred within the last 25,000 years.

Extent and geological context

The Taupo Volcanic Zone is approximately 350 kilometres (217 mi) long by 50 kilometres (31 mi) wide. Mount Ruapehu marks its southwestern end, while the submarine Whakatane volcano (85 kilometres (53 mi) beyond White Island) is considered its northeastern limit.

It forms a southern portion of the active Lau-Havre-Taupo back-arc basin, which lies behind the Kermadec-Tonga subduction zone. Volcanic activity continues to the north-northeast, along the line of the Taupo Volcanic Zone, through several undersea volcanoes (known as Clark, Tangaroa, the Silents and the Rumbles), then shifts eastward to the parallel volcanic arc of the Kermadec Islands and Tonga. Although the back-arc basin continues to propagate to the southwest, with the South Wanganui Basin forming an initial back-arc basin, volcanic activity has not yet begun in this region.

South of Kaikoura the plate boundary changes to a transform boundary with oblique continental collision uplifting the Southern Alps in the South Island. A subduction zone reappears southwest of Fiordland, at the southwestern corner of the South Island, although here the subduction is in the opposite direction. Solander Island is an extinct volcano associated with this subduction zone, and the only one that protrudes above the sea.

Scientific study

Recent scientific work indicates that the Earth's crust below the Taupo Volcanic Zone may be as little as 16 kilometres thick. A film of magma 50 kilometres (30 mi) wide and 160 kilometres (100 mi) long lies 10 kilometres under the surface. The geological record indicates that some of the volcanoes in the area erupt infrequently but have large, violent and destructive eruptions when they do. There is also some possible rifting in the Taupo Volcanic Zone.

Volcanoes, lakes and geothermal fields

The following Volcanic Centers belong to the Taupo Volcanic Zone:

Rotorua, Okataina, Maroa, Taupo, Tongariro and Mangakino.

Inside the Tarawera rift
In 1886, Mount Tarawera produced New Zealand's largest historic eruption
Lady Knox Geyser
Lady Knox Geyser, Waiotapu geothermal area
CratersOfTheMoon1
Craters of the Moon geothermal area
MtRuapehu 23oct2002
Composite satellite image of Mount Ruapehu
Rotorua.Caldera.Mount.Tarawera
Satellite view of the Lake Rotorua Caldera. Mount Tarawera is in the lower right corner.
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Southwest side of Mount Tarawera, Mount Edgecumbe on the background.

Other important features of the TVZ include the Whakatane, Ngakuru and Ruapehu grabens.

Panorama across Lake Taupo

Taupo Volcanic Zone Facts for Kids. Kiddle Encyclopedia.