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Volcanism of New Zealand

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Major volcanoes of New Zealand

The volcanism of New Zealand has been responsible for many of the country's geographical features, especially in the North Island. It has also claimed many lives. While the land's volcanic history dates back to before the Zealandia microcontinent rifted away from Gondwana, activity continues today with minor eruptions occurring every few years. This recent activity is due to the country's position on the boundary between the Indo-Australian and Pacific Plates, a part of the Pacific Ring of Fire.

New Zealand's rocks record examples of almost every kind of volcanism observed on Earth, including some of the world's largest eruptions in geologically recent times.

Areas

There are remnants of volcanic activity throughout most of New Zealnd, but there are several areas where this is more obvious, and some where activity is ver much continuing.

Auckland volcanic field

This is a generally monogenetic volcanic field in the North Island of New Zealand. Basaltic in nature, it underlies much of the metropolitan area of the city of Auckland where the field's many vents have produced a diverse array of explosion craters, scoria cones, and lava flows. The most recent to erupt was Rangitoto in Auckland Harbour 600–700 years ago. Currently dormant, the field is likely to erupt again within the next "hundreds to thousands of years" (based on past events), a very short timeframe in geologic terms.

Taupo Volcanic Zone

This is the major volcanic field in New Zealand and is approximately 350 kilometres long by 50 kilometres wide. Mount Ruapehu marks its southwestern end, and it contiues up through Tarawera, Tongariro, Ngauruhoe, Ruapehu, the Rotorua thermal area, Mount Tarawera and out to White Island - with the submarine Whakatane volcano (85 kilometres beyond White Island) considered its northeastern limit.

Banks Peninsula

The peninsula comprises the eroded remnants of two large stratovolcanoes (Lyttelton formed first, then Akaroa). These formed due to intraplate volcanism between approximately eleven and eight million years ago (Miocene) on a continental crust. The peninsula formed as offshore islands, with the volcanoes reaching to about 1,500 m above sea level. Two dominant craters formed Lyttelton and Akaroa Harbours. The portion of crater rim lying between Lyttelton Harbour and Christchurch city forms the Port Hills.

Oamaru

In this area around 35 to 30 Ma ago on the submerged continental shelf small Surtseyan volcanoes formed the "Waiareka-Deborah volcanic group"

Otago Peninsula

The Dunedin Volcanic Complex began with basaltic eruptions on the Otago Peninsula. Large central-vent structures formed, and then large domes - with seawater interacting explosively with erupting submarine magma..

Solander Islands

The Solander Islands are a small chain of uninhabited volcanic islets lying at 46°34′S 166°53′E / 46.567°S 166.883°E / -46.567; 166.883, close to the western end of the Foveaux Strait in southern New Zealand. Solander Island is an extinct volcano associated with this subduction zone, and the only one that protrudes above the sea. ).

Major eruptions

Main vent of Whakaari/White Island in 2000.
This section needs expansion. You can help by adding to it. (May 2008)

Modern Lake Taupo partly fills the caldera generated during this eruption and tephra from the eruption covered much of the central North Island with ignimbrite up to 200 metres deep. Most of New Zealand was affected by ash fall, with even an 18 cm ash layer left on the Chatham Islands, 1,000 km away. Later erosion and sedimentation had long-lasting effects on the landscape, and caused the Waikato River to shift from the Hauraki Plains to its current course through the Waikato to the Tasman Sea.

The Hatepe eruption's three main vents ran parallel to Lake Taupo's current southeastern shore.
  • The Hatepe eruption; sometimes referred to as the Taupo eruption, around the year AD 180 was Lake Taupo's most recent major eruption, and New Zealand's largest eruption during the last 20,000 years. It ejected some 120 cubic kilometres of material (rating a 7 on the Volcanic Explosivity Index scale), of which 30 cubic kilometres was ejected in the space of a few minutes. It is believed that the eruption column was 50 kilometres high, twice as high as the eruption column from Mount St. Helens in 1980. This makes it one of the most violent eruptions in the last 5000 years (alongside the Tianchi eruption of Baekdu at around 1000 and the 1815 eruption of Tambora). The resulting ash turned the sky red over Rome and China.
  • Mount Tarawera erupted on June 10, 1886, spewing ash and debris over 16,000 km², destroying the Pink and White Terraces, and three villages, including Te Wairoa, and claiming the lives of at least 153 people. Approximately 2 cubic kilometres of tephra was erupted.
  • On December 24, 1953 the Tangiwai disaster, with the loss of 151 lives, occurred when the Tangiwai railway bridge across the Whangaehu River collapsed from a lahar in full flood, just before an express train crossed it. This was a consequence of a 1945 eruption which had emptied the crater lake and dammed the outlet with tephra.

Cultural effects

This section needs expansion. You can help by adding to it. (May 2008)

The Māori had many myths and legends regarding the volcanoes. The most prominent regards the location of Taranaki, Tongariro and Ngauruhoe as they stand today. It is said that the other two volcanoes competed for the love of Tongariro, at which Taranaki lost. Defeated, Taranaki moved it to its present location near New Plymouth.

See also

Notes

  1. Beca Carter Hollings & Ferner (2002). Contingency Plan for the Auckland Volcanic Field, Auckland Regional Council Technical Publication 165. Accessed 2008-05-12.
  2. "Eruptions and deposition of volcaniclastic rocks in the Dunedin Volcanic Complex, Otago Peninsula, New Zealand", Ulrike Martin
  3. Wilson, Colin J. N. (2001). "The 26.5 ka Oruanui eruption, New Zealand: an introduction and overview". Journal of Volcanology and Geothermal Research. 112: 133–174. doi:10.1016/S0377-0273(01)00239-6.
  4. Manville, Vern & Wilson, Colin J. N. (2004). "The 26.5 ka Oruanui eruption, New Zealand: a review of the roles of volcanism and climate in the post-eruptive sedimentary response". New Zealand Journal of Geology & Geophysics. 47: 525–547.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  5. Wilson, Colin J. N.; et al. (2006). "The 26.5 ka Oruanui Eruption, Taupo Volcano, New Zealand: Development, Characteristics and Evacuation of a Large Rhyolitic Magma Body". Journal of Petrology. 47 (1): 35–69. doi:10.1093/petrology/egi066. {{cite journal}}: Explicit use of et al. in: |author= (help)
  6. Talbot, J. P. (1994). "Dilute gravity current and rain-flushed ash deposits in the 1.8 ka Hatepe Plinian deposit, Taupo, New Zealand". Bulletin of Volcanology. 56 (6–7): 538–551. doi:10.1007/BF00302834. {{cite journal}}: Cite has empty unknown parameter: |month= (help); Unknown parameter |coauthors= ignored (|author= suggested) (help)
  7. "Taupo - Eruptive History". Global Volcanism Program. Smithsonian Institution. Retrieved 2008-03-16.
  8. Wilson, C. J. N. (1980). "A new date for the Taupo eruption, New Zealand". Nature. 288: 252–253. doi:10.1038/288252a0. {{cite journal}}: Cite has empty unknown parameter: |month= (help); Unknown parameter |coauthors= ignored (|author= suggested) (help)
  9. Dench, p 114
  10. "Okataina: Eruptive History". Global Volcanism Program. Smithsonian Institution.

References

  • Dench, Alison; Essential Dates: A Timeline of New Zealand History, Auckland: Random House, 2005 ISBN 1869416899

External links

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