Taupō Volcanic Zone

Thermally active area - Craters of the Moon, North Island, New Zealand.

Taupo volcanic area

Craters of the Moon

Craters of the Moon

Obsidian specimen fallen from cliff

Obsidian veins at Ben Lomond

Obsidian boulders at Ben Lomond

The Taupo Volcanic Zone is an active volcanic area in the North Island of New Zealand. It is named after Lake Taupo, which is 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. The Rotorua caldera produced its most recent giant eruption about 240,000 years ago, while Taupo erupted an estimated 1,170 km³ of material 26,500 years ago (over 290 times more material than the 1980 Mt St Helens eruption). This is possibly the Earth's largest volcanic eruption in recent geological time.

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 100 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 as it was sufficiently large, due to the ash expulsion, to turn the sky red over Rome and China (as documented in Hou Han Shu).

Extent of zone

The Taupo Volcanic Zone is about 50 kilometres wide and about 300 kilometres long and lies over a subduction zone in the earth's crust. Mount Ruapehu marks its southwestern end, while White Island is considered its northeastern limit. The subduction zone appears to extend further to the northeast, as along the line of the Taupo Volcanic Zone lie several undersea volcanoes known as the Rumbles and also the Kermadec Islands, with another caldera at Raoul Island. 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 5 kilometres thick. Beneath this lies a film of magma 50 kilometres (30 mi) wide and 160 kilometres (100 mi) long.[1] Because of the thin crust and widely dispersed magma, all known volcanoes in the area are considered active, even if they have not erupted recently. 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

Craters of the Moon

The Craters of the Moon thermal area in Wairakei Tourist Park sprang up in the 1950s, when the nearby power station lowered underground water levels. The 30 minute walk visits bubbling craters, mud pools and steam vents. You can also see a lot of interesting plants that have adapted to thrive in the hot, steamy conditions.

External links

• Further information on Taupo volcanics
• Tectonic plate information
• The Taupo Volcanic Zone with Māori Freehold Land (1995) - showing geothermal fields
• Earthquake risks
• Measurement and implication of “effective” viscosity for rhyolite flow emplacement PDF
• New Zealand's volcanoes: The Taupo volcanic centre
• Stevenson, R. J., R. M. Briggs and A. P. W. Hodder (1994). "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.