Taupo Volcanic Zone

The Taupo Volcanic Zone is a highly active volcanic area in the North Island of New Zealand. It is named after Lake Taupo, the flooded caldera of the largest volcano in the zone.

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 humans was that of Mount Tarawera in 1886, which killed around 150 people. The Rotorua caldera has been dormant longer, producing its most recent giant eruption about 240,000 years ago. Taupo erupted an estimated 1,170 km³ of material 26,500 years ago, in the Earth's most recent eruption reaching the highest level on the Volcanic Explosivity Index.

The last major eruption from Lake Taupo was in 181 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 of land with volcanic ash. A total of 120 km³ of material is believed to have been ejected, and over 30 km³ of material is estimated to have been ejected in just a few minutes. The date of this activity is known since the ash expulsion was sufficiently large to turn the sky red over Rome and China (as documented in Hou Han Shu).

Extent of zone

The Taupo Volcanic Zone is 350 kilometres long by 50 kilometres wide and lies over a subduction zone in the earth's crust. Mount Ruapehu marks its southwestern end, while the submarine Whakatane volcano (85 kilometres beyond White Island) is considered its northeastern limit. [Gamble, J. A., I. C. Wright and J. A. Baker (1993). " [http://www.rsnz.org/publish/nzjgg/1993/40.php Seafloor geology and petrology in the oceanic to continental transition zone of the Kermadec-Havre-Taupo Volcanic Zone arc system, New Zealand] " "New Zealand Journal of Geology and Geophysics", 36, 417-435.] The subduction zone extends further to the northeast, and associated volcanic activity continues along the line of the Taupo Volcanic Zone through several undersea volcanoes (known as the Rumbles), the Kermadec Islands, and Tonga. There is no volcanic activity to the southeast, although the subduction zone continues as far south as Kaikoura, where the plate boundary changes to continental collision which is uplifting the Southern Alps in the South Island. A subduction zone reappears southwest of Fiordland, at the southwestern corner of the South Island. For this reason the Taupo Volcanic Zone is thought to be the western end of the Pacific Ring of Fire, which marks out the subduction zones around the Pacific Ocean.

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. [ [http://www.stuff.co.nz/4202557a11.html Central North Island sitting on magma film] Paul Easton, The Dominion Post, 15 September 2007. Retrieved 2008-03-16] [W. Heise, H.M. Bibby and T.G. Caldwell (2007). [http://www.cosis.net/abstracts/EGU2007/01311/EGU2007-J-01311.pdf?PHPSESSID=e Imaging magmatic Processes in the Taupo Volcanic Zone (New Zealand) with Magnetotellurics] , "Geophysical Research Abstracts", Vol. 9, 01311.] 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 and thermal areas

See also List of volcanoes in New Zealand#Taupo Volcanic Zone.

* Whakaari/White Island
* Mayor Island/Tuhua
* Mount Mauao
* Mount Edgecumbe
* Tikitere/Hell's Gate
* Rotorua Caldera
* Whakarewarewa
* Okataina volcanic centre
** Haroharo caldera
** Mount Tarawera
* Waimangu
* Ben Lomond rhyolite dome (contains obsidian)
* Wai-O-Tapu
* Orakei Korako
* Wairakei
* Craters of the Moon
* Mount Tauhara
* Lake Taupo
** Horomatangi Reefs
* Waihi (on the southwestern coast of Lake Taupo)
* Tokaanu
* Turangi
* Mount Tongariro
** Mount Ngaruahoe
* Mount Ruapehu

ee also

* Volcanism in New Zealand

References

External links

* [http://www.laketauponz.com/aboutlaketaupo.cfm?method=displaysubsection&sectionid=73dea3d0-efad-ba3f-9d50-1c4db6b33ec3 Further information on Taupo volcanics]
* [http://volcano.und.nodak.edu/vwdocs/volc_images/australia/new_zealand/new_zealand.html Tectonic plate information]
* [http://www.maoriland.govt.nz/STATS/Geotherm.htm The Taupo Volcanic Zone with Māori Freehold Land (1995) - showing geothermal fields]
* [http://www.envbop.govt.nz/CD/Earthquake.asp Earthquake risks]
* [http://www.geophysik.uni-frankfurt.de/~nickbagd/sdbm.pdf Measurement and implication of “effective” viscosity for rhyolite flow emplacement] PDF
* [http://www.gns.cri.nz/what/earthact/volcanoes/nzvolcanoes/taupoprint.htm New Zealand's volcanoes: The Taupo volcanic centre]
* Stevenson, R. J., R. M. Briggs and A. P. W. Hodder (1994). " [http://www.rsnz.org/publish/nzjgg/1994/29.php Physical volcanology and emplacement history of the Ben Lomond rhyolite lava flow, Taupo Volcanic Centre, New Zealand] " "New Zealand Journal of Geology and Geophysics", 37. pp. 345-358.