Lake Taupo, New Zealand

Lake Taupo, New Zealand Supervolcano

Country:	New Zealand
Subregion Name:	New Zealand
Volcano Number:	0401-07=
Volcano Type:	Caldera
Volcano Status:	Radiocarbon
Last Known Eruption:	210 AD (?)
Summit Elevation:	760 m	2,493 feet
Latitude:	38.82°S	38°49'0"S
Longitude:	176.00°E	176°0'0"E
Taupo, the most active rhyolitic volcano of the Taupo volcanic zone, is a large, roughly 35-km-wide caldera with poorly defined margins. It is a type example of an "inverse volcano" that slopes inward towards the most recent vent location. The Taupo caldera, now filled by Lake Taupo, largely formed as a result of the voluminous eruption of the Oruanui Tephra about 22,600 years before present (BP). This was the largest known eruption at Taupo, producing about 1170 cu km of tephra. This eruption was preceded during the late Pleistocene by the eruption of a large number of rhyolitic lava domes north of Lake Taupo. Large explosive eruptions have occurred frequently during the Holocene from many vents within Lake Taupo and near its margins. The most recent major eruption took place about 1800 years BP from at least three vents along a NE-SW-trending fissure centered on the Horomotangi Reefs. This extremely violent eruption was New Zealand's largest during the Holocene and produced the thin but widespread phreatoplinian Taupo Ignimbrite, which covered 20,000 sq km of North Island.

Taupo’s History

Taupo Volcano has been in existence for more than 65 000 years. In that time it has shown a random pattern of exceptionally large events interspersed by smaller eruptions. This is a pattern typical of all the major rhyolite volcanoes of the central North Island and together they have produced large eruptions about every 50,000 years. At Taupo the Oruanui and the Taupo eruptions are part of this larger pattern.

Lake Taupo, New Zealand Supervolcano

credit:

http://volcano.und.nodak.edu/vwdocs/volc_images/australia/new_zealand/taupo.html

Pre 65,000 years ago
All deposits at Taupo including a number of early lava domes clearly post-date the exceptionally large Whakamaru ignimbrite eruption dated at 330,000 years ago. About 150,000 years ago new activity formed a pumice-rich ignimbrite found along the northern shores of the lake, several basalt scoria cones and tuff rings about Acacia Bay and Mt. Tauhara. Our knowledge of this time intervals is very incomplete as few deposits of this age are exposed.
65,000 to 27,000 years ago
Between 65,000 years and 27,000 years ago there was a series of at least five explosive eruptions, from vents now under Lake Taupo. The older four eruptions produced layers of coarse pumice. The youngest produced fine grey ash suggesting the mixing of lake water with erupting magma.
The Oruanui eruption 26,500 years ago
The largest eruption from Taupo occurred 26,500 years ago producing 300 km³ of ignimbrite, 500 km³ of pumice and ash fall and a unknown volume of material inside the caldera. The Oruanui eruption is thought to have formed the caldera now filled by Lake Taupo, but this large eruption also shows the influence of lake water in its fine grain size and abundant evidence for heavy rain during the eruption. This implies the existence of a large lake prior to the eruption. The Oruanui ignimbrite is seen in many road cuttings about Taupo, draped by the layers of younger tephra. Fine ash from this eruption has been found throughout New Zealand and in many offshore core samples.

Credit: VOLCANIC HAZARDS AT TAUPO VOLCANIC CENTRE By Paul Froggatt

Victoria Link Ltd & Research School of Earth Sciences, Victoria University of Wellington

http://www.gns.cri.nz/what/earthact/volcanoes/nzvolcanoes/taupoprint.htm

credit: NASA, The Discovery Channel, The Smithsonian Institute, USGS