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New Zealand Volcanos

NZ has its share of volcanos and is part of the Pacific “ring of fire”. All are based in North island. The geology of NZ is very interesting, see also New Zealand Geology and Earthquakes and Volcanoes of Auckland

New Zealand contains the world's strongest concentration of youthful rhyolitic volcanoes, and voluminous sheets blanket much of North Island, so now you know!

Planning a road trip of North Island, use NZ volcanoes as a basis for your journey.

The earliest historically-dated eruption was at Whakaari/White Island in 1826. Much of the region north of New Zealand's North Island is made up of seamounts and small islands, including 16 submarine volcanoes. In the last 1.6 million years, most of New Zealand's volcanism is from the Taupo Volcanic Zone.

see http://www.geonet.org.nz/index.html

Mount Ruapehu

at the southern end of the Taupo Volcanic Zone, is one of the most active volcanoes.It began erupting at least 250,000 years ago. In recorded history, major eruptions have been about 50 years apart, in 1895, 1945 and 1995–1996. Minor eruptions are frequent, with at least 60 since 1945. Some of the minor eruptions in the 1970s generated small ash falls and lahars (mudflows) that damaged skifields. Between major eruptions, a warm acidic crater lake forms, fed by melting snow. Major eruptions may completely expel the lake water. Where a major eruption has deposited a tephra dam across the lake's outlet, the dam may collapse after the lake has refilled and risen above the level of its normal outlet, the outrush of water causing a large lahar. In 2000, the ERLAWS system was installed on the mountain to detect such a collapse and alert the relevant authorities. Go to Ruapehu

Rotorua

The 22 km wide Rotorua caldera is the north-westernmost caldera of the Taupo Volcanic Zone, it is also the only single-event caldera. The city of Rotorua lies close to the active geothermal fields of Tikitere and Whakarewarewa. Most Recent Eruption

  • When: less than 25,000 years ago
  • Effects: Eruption of three lava domes.

Okataina

The Okataina Volcanic Centre extends from Lake Rotoma in the north to Waiotapu in the south. It includes the large, young volcanoes of Tarawera and Haroharo, with others at Okareka and Rotoma. More than 35 vents have been active at Okataina during the last 21,000 years. Most Recent Eruption

Where: Tarawera

When: June 1886

Effects: The 1886 eruption is the most lethal to have occurred in New Zealand’s recorded history. Rumblings from the Tarawera eruption were heard as far south as Blenheim, in the South Island. During the eruption a series of large explosions opened up a rift 17 km long, which expelled ash and rocks for a few hours. When hot magma came into contact with Lake Rotomahana, huge explosions covered the region with mud and ash up to one metre deep and many buildings collapsed. Three villages were buried under hot heavy ash and mud and 108 people killed, the Māori village of Te Wairoa, its Pa and whares were completely buried. The Pink and White Terraces, considered one of the great natural wonders of the world were also destroyed.

Update:Scientists using underwater robots have discovered remnants of the Pink Terraces on the floor of Lake Rotomahana, near Rotorua. The terraces, once described as the eighth wonder of the natural world, were buried in the eruption of Mt Tarawera in 1886. They were rediscovered this week during a joint New Zealand and American mission to map the lake floor and investigate geothermal activity at Lake Rotomahana.

Project leader Cornel de Ronde, of GNS Science, said his team was elated at the discovery. He is “certain” they have found the remains of the terraces. “The first sonar image gave a hint of a terraced structure so we scanned the area twice more and we are now 95 per cent certain we are seeing the bottom two tiers of the Pink Terraces. “This discovery puts to rest more than a century of speculation as to whether any part of the Pink and White Terraces survived the eruption. Highlights in a science career don't come any better than this.”

Full Article: NZ Herald Article

White Island

The trip out to white Island is high on the list to do, seems all our visitors have been on it. Link at end of article.

Sitting 48 km offshore, White Island (Whakāri) is New Zealand’s most active cone volcano which has been built up by continuous volcanic activity over the past 150,000 years. About 70 percent of the volcano is under the sea, making this massive volcanic structure the largest in New Zealand.

A sulphur mining venture began on the island in 1885; this was stopped abruptly in 1914 when part of the crater wall collapsed and a landslide destroyed the sulphur mine and miners' village; twelve lives were lost. The remains of buildings from that era are now a tourist attraction.

Although privately owned, White Island became a private scenic reserve in 1953, and daily tours allow more than 10,000 people to visit White Island every year. GeoNet monitors volcanic activity and visits the island around 10 times a year.

SEE:http://www.whiteisland.co.nz/

Taranaki

Also known as Egmont Volcano, the 2518 m tall cone volcano last erupted about 250 years ago at the culmination of eight eruptions in the preceding 300 years. The western 1500 km2 of the Taranaki region is a volcanic landscape that has been constructed from the products of volcanic eruptions principally derived from the volcano. These deposits around the base of the volcano record intermittent volcanic activity at this site for the last 130,000 years.

On three occasions, twice within a very short period of geological time, former cones have collapsed to the north-east, south-east and the west. In each instance extremely large volumes of material flowed more than 40 km across the landscape, reaching the present Taranaki coastline. They have created the distinctive mounds or hummocks on the lowlands surrounding the volcano. Most Recent Eruption

  • When: around 1755
  • Effects: An explosive ash eruption.
  • Note: Two further minor volcanic events also took place in the early 1800s and in 1854.

SEE:Taranaki (Mount)

Taupo

Thats quite a hole in the ground

Taupo volcano first began to erupt over 300,000 years ago. It is very large and has many vents, most of which are now under Lake Taupo. Geological studies of Taupo show that the volcano makes up only the northern half of the lake and a small surrounding area but there have been numerous eruptions from different sites within this large volcano. Taupo is not a large mountain because the eruptions have been so explosive that all material has been deposited far from the vent and subsequent collapse of the ground has formed a caldera (a collapsed volcano). Most Recent Eruption

  • Where: north-eastern Lake Taupo
  • When: about 1,800 years ago
  • Effects: The Taupo eruption was the most violent eruption in the world in the last 5,000 years; it was a complex series of events. The first phases of the eruption produced a series of five pumice and ash fall deposits over a wide area of the central North Island, especially east of Taupo and beyond Napier into Hawke Bay. The eruption culminated with a large and very energetic pyroclastic flow that devastated an area of about 20,000 km2 and filled all the major river valleys of the central North Island with pumice and ash. These pumice deposits can still be seen today and many of the major rivers in the North Island carry large amounts of this pumice when in flood. Rounded pumice found on the beaches of the North Island have come from this eruption. The Taupo eruption took place from a line of vents near the eastern side of the modern lake.

Tongariro

Tongariro is a complex of multiple volcanic cones constructed over a period of 275,000 years. The active vents include Te Māri, Emerald, North Crater and Red Crater. There have been five reported eruptions from the Te Māri craters and Red Crater between 1855 and 1896 but they have been dormant since then. Most Recent Eruption

  • Where: Te Māri
  • When: 1869, 1892 and 1896
  • Effects: In 1869 a large eruption (accompanied by an earthquake) formed the upper Te Māri Crater during an explosive eruption. Māori descriptions talk of “bright red flame through the smoke that would burst and fall like snow”. In November 1892 Te Māri again belched forth an immense quantity of steam, mud and boulders; the ejected material rose 2,000 - 3,000 feet (600 - 900 m) before rushing down the mountain side. The last eruption began in November 1896 and continued until the end of the year.

SEE:http://www.nationalpark.co.nz/tongariro-alpine-crossing/tongariro-alpine-crossing

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