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Learn a little about the Taupo volcanic region, or use this page as a reference for the volcanoes and geothermal areas you have already discovered with Helistar Helicopters.
Ruapehu - Ngauruhoe - Tongariro - Taupo
Tarawera - White Island - Geothermal Activity
The North Island of New Zealand is on the edge of the Australian Plate - one of the pieces of the earths crust. To the east is the Pacific Plate, which is sliding underneath the North Island at about the speed your fingernail grows. The friction between these two plates creates enough heat to melt the rocks and in places this molten rock (magma) escapes to the surface creating a volcano.
This heat source also creates the many colourful hot springs, boiling mud pools and geysers.
Sudden movement between the two plates sometimes causes earthquakes. In this area the center of the earthquakes is usually very deep so violent quakes are not typical.
Above the edge of the diving Pacific Plate - about 75km underground by this stage - there are a line of volcanoes. They run in a north easterly direction from Ruapehu to Taupo, Rotorua, and onwards through White Island.
Click to see a map.
During an eruption, as the Magma rises, gas is released in a similar way to opening a soft drink bottle. The amount of gas varies according to the makeup of the magma and is one of the things that give a more energetic eruption. On your visit to Lake Taupo, try throwing one of the beach rocks into the water - they float! The pumice rocks from Lake Taupo are very porous, suggesting a extremely violent eruptions. There are a few other clues to the violence of Lake Taupo's eruptions, like the size of the hole it has left behind - the lake is the same size as Singapore!.
There are inherent risks living in a volcanic zone, as there are living in an area prone to earthquakes, snow or lightning storms, tornadoes, floods or any of the awesome forces nature has to dish out. Most of the eruptions though, are more disruptive than destructive and the risks are actually very small.
There have been 3 volcanic events in New Zealand's history that have caused death - only one of them was from an actual eruption:-
Mt. Tarawera's 1886 eruption killed 150 people.
White Island's 1914 crater wall collapse killed 11 Sulphur Miners.
Mt. Ruapehu's Crater Lake rim collapsed in 1953 causing a Lahar that wiped out a rail bridge - a train shortly after plummeted into the river killing 151 people.
The Tongariro National Park was formed in 1887 when Te Heuheu,
the Chief of the Ngati Tuwharetoa Tribe gifted the peaks of the volcanoes to the
Mountains - especially volcanoes are very sacred to the Maori, and this gift was an incredible show of wisdom and forethought to protect the area in a time when Europeans were settling to New Zealand with little awareness of the Maori culture.
Tongariro was the 2nd National Park to be formed in the World after Yellowstone in the United States. The Park has since grown from just the peaks to a much larger area. A visit to the park, by air or ground, will give you an appreciation of the power that nature holds - the ongoing gift of Te Heuheu.
The Ruapehu Massif is built of multiple cones. The highest mountain in the North Island, Ruapehu stands at 2797m (9175ft). The last eruptions were in the winters of 1996 and 1995.
Ruapehu has a lake in it's currently active crater about 1km
across. On rare occasions
with no activity the lake has frozen over, but the temperature easily reaches 60�.
Crater Lake introduces it's own danger of lahar's or volcanic mud flows that are
created when lake water and volcanic debris are thrown from the crater, flowing
down the valleys at speeds of up to 90 km/h.
Ruapehu is a popular winter playground, with 3 ski fields on it's slopes - with several thousand people frolicking in the snow, lahars remain the most serious hazard on Ruapehu.
The lake is now quite acidic and is refilling since the '96 eruption. Certainly not recommended at present, bathing in the crater lake has been a popular pastime for skiers. The first person to swim across the lake was Hugh Girdlestone in 1908.
Although no one was hurt in that time, a few hard lessons were learned in the '60's and '70's. Buildings and ski lifts are no longer built in the valleys, and a Lahar Warning System allows skiers at the Whakapapa ski field a few minutes to clamber to higher ground.
During the larger eruptions of 1996, ash was thrown spectacularly 20km into the air. Lahars flowed down many of the valleys - including some in the Whakapapa ski field as Crater Lake displaced it's water. Towards the end of the 1996 eruption the lake was empty, and shows of flying lava could be seen.
There are two older craters on the top of Ruapehu. The crater outlines are now seen around the large flat plateau of ice that permanently fills the craters at a depth of around 180 meters.
The oldest rocks exposed on Ruapehu are about 230,000 years old, and like Tongariro it is thought the volcano may have been active for about 1,000,000 years.
"It's what a volcano is supposed to look like"
The perfect cone of Ngauruhoe is very young - only about 2500 years old, and very active - the most active in New Zealand after White Island, with an eruption every 2-3 years until it's last event in 1975. The crater used to steam continuously but it is thought the vent is now blocked - preventing any further activity. There are two craters on the top of Ngauruhoe, one inside the other. The inside crater was formed during a larger eruption in 1942. Fresh lava flows can be seen on the slopes from eruptions in the '40's & '50's.
The Tongariro Massif is a complex arrangement of cones - some eroded by the ice
age 6500 years ago, and
some formed since. The most recent vent of Tongariro is Mt. Ngauruhoe.
There has been considerable activity from Tongariro in the last 2000 years, since 1855 there have been several eruptions from the Upper Te Maari Crater and the Red Crater. There is a continuous steam discharge from Ketetahi on the northern face of Tongariro. Ketetahi releases about the same energy as the Wairakei Geothermal Power Station in Taupo which supplies 3% of New Zealand's electricity.
There are a dozen craters on Tongariro. The Northern Crater - the biggest crater - is a kilometer across. Some of the explosion pits on Tongariro have filled with water, giving a brightly coloured contrast to the surrounding landscape. Activity from Ketetahi and the Red Crater has been continuous since observation began.
"The more a volcano looks like a volcano, the smaller it really is"
Click on the thumbnail below to see a comparison of Taupo to a few other well known eruptions:-
Tranquil Lake Taupo has been an active volcano for more than 65,000 years. In
that time it has shown a random pattern of exceptionally large eruptions interspersed with
many smaller events.
The area around Taupo is covered in 10m of pumice deposited from eruptions in the last 22,000 years and a further 5m from it's largest eruption 26,500 years ago.
Taupo is not a large mountain because the eruptions have been so large and so violent that all material has been deposited far from the vent and subsequent collapse of the ground has formed a caldera (a collapsed volcano). Many of the lakes around Rotorua were formed in the same way.
Click here to see how Caldera's are formed
Taupo's largest eruption occurred 26,500 years ago producing 300km� of Ignimbrite (from pyroclastic flows) 500km� of pumice and ash and an unknown volume of material inside the caldera. There was a large lake already present at the time but this eruption is thought to have created the caldera now filled by Lake Taupo. Lake Taupo covers about 600km�.
The last eruption in 181 AD - about 1800 years ago was unusually violent, throwing
out about 100km� of material. A large and very energetic pyroclastic flow
finished the eruption which devastated an area of about 20,000km�, and filled
all the major river valleys of the Central North Island with pumice and ash.
Rounded pumice found on the beaches around the North Island come from this eruption.
The ash in the atmosphere was recorded at the time by both the Romans and Chinese.
Over the past 26,000 years there have been 28 major eruptions spaced in time by between 50 and 5000 years. Three of these have caused destructive pyroclastic flows at 1800, 3550 and 9950 years ago. There is no pattern between these eruptions making it difficult to predict when the next eruption may be, but the chance of a pyroclastic flow in our time is very slim.
On the 10th of June 1886, the eruption from Mt Tarawera - near Rotorua - came with little warning, causing major destruction and killing 150 people. It is the largest eruption in New Zealand's populated times.
With little more than a few earthquakes around 12:30am,
Tarawera started erupting about an hour later.
By 2:20am craters along the whole length of the mountain had begun erupting throwing ash 10km into the air.
At 3:20am Lake Rotomahana - further along the Tarawera rift - begun erupting, and eruptions continued along the 17km long rift until about 6:00am.
Events from Lake Rotomahana were particularly explosive as the magma reacted with the lake water, causing most of the casualties from the eruption.
A popular place to visit today is the Buried Village which has Whare's (houses) still buried in ash. The eruption also destroyed the Pink and White Terraces - two beautiful silica terraces on the side of Tarawera which were a huge worldwide attraction in a time when Yellowstone National Park in the USA had not yet begun to attract popular attention.
Tarawera is a part of the Okataina Volcanic Center - a wider
area which lies
to the east of Lake Rotorua. This area has been the site of 5 or 6 huge
eruptions between 400,000 and 50,000 years ago. Like Taupo, these eruptions
caused the surrounding ground to collapse causing a basin known as a caldera.
These massive eruptions buried large area's under 50m - 100m of pumice that was hot enough to weld together forming ignimbrite, which looks like concrete.
White Island is New Zealand's most active volcano, and has
recently (July, 2000) had it's largest eruption in 20 years. Located 48 km offshore, the
eruptions are clearly visible from the Bay of Plenty, but no eruptions in the
last 160 years have caused any significant effects to the inhabitants of the
Since 1976 the Island has been more active than in the last few hundred years, sparking considerable interest.
Although not evident in history, recent study has shown White Island is capable of large eruptions. This potential arises from the large magma body beneath the island.
Falling ash and pumice is the usual threat, but - as with other offshore volcanoes - the possibility of a tsunami has also been discussed. It would take a very large eruption from White Island to cause such an event. (Krakatoa's 1883 eruption caused a tsunami)
A hot lake was permanently drained on White Island's crater floor in 1913 to allow the sulphur deposits to be mined. In 1914 the crater wall collapsed causing a hot avalanche that buried 11 sulphur miners.
It is well known that Rotorua holds numerous geothermal
area's, many of which have been developed with walking tracks so anyone can
enjoy the wonders of these colourful and vigorous scenes.
It is less known that there are countless other geothermal area's along the whole Taupo Volcanic Zone. Even the locals of Lake Taupo are surprised at the activity only a few kilometers from their homes. The hidden geothermal area's around Taupo are difficult to access (except by air) and unstable to walk around, so scores of brightly coloured hot lakes and mud pools have been all but forgotten.
Somewhere not so far beneath the surface here is magma or
molten rock. This Magma is the heat source for the many different geothermal
features around Taupo. The cycle of geothermal activity starts with rainwater
percolating deep into the ground finding it's way through cracks and fractures
in the earth. As it seeps deeper the water becomes superheated under pressure
and rapidly finds it's way back to the surface. It reaches the surface as
geysers or hot springs, fumaroles and mud pools.
These area's can be fantastically active with dazzling colours caused by the different minerals and unusual algae's and mosses that can grow in this environment.
There are several geothermal power stations in the North
Island that use steam to generate electricity. Wairakei Power Station -
completed in 1958 - just north of Taupo was the only the second geothermal
powered station to be built in the world. The bores that extract the steam from
the ground are generally between 600 and 1200 meters deep.
Wairakei produces approximately 3% of New Zealand's electricity.
Unfortunately the power station has destroyed 2 superb geyser fields by lowering the water table.