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61-574: Lake Taupō , in the centre of New Zealand 's North Island , fills the caldera of the Taupō Volcano , a large rhyolitic supervolcano . This huge volcano has produced two of the world's most powerful eruptions in geologically recent times. The volcano is in the Taupō Volcanic Zone within the Taupō Rift , a region of rift volcanic activity that extends from Ruapehu in the south, through

122-478: A Ngāti Tūwharetoa village known as Te Rapa near the springs of Maunga Kākaramea . It was covered in a landslide on 7 May 1846 which killed 60 people, including the iwi's chief Mananui Te Heuheu Tūkino II . Pyroclastic flow Pyroclastic flows are the most deadly of all volcanic hazards and are produced as a result of certain explosive eruptions ; they normally touch the ground and hurtle downhill or spread laterally under gravity. Their speed depends upon

183-518: A French island in the Caribbean. Pyroclastic flows that contain a much higher proportion of gas to rock are known as "fully dilute pyroclastic density currents" or pyroclastic surges . The lower density sometimes allows them to flow over higher topographic features or water such as ridges, hills, rivers, and seas. They may also contain steam, water, and rock at less than 250 °C (480 °F); these are called "cold" compared with other flows, although

244-596: A deformation event in the north-west portion of the volcano without seismic or deformation events being observed in closer volcanoes to that earthquake's epicentre. From May through December 2022 there was increased earthquake activity with lakeside slumping and inundation from a small tsunami and ground deformation . The Volcanic Alert Level for Taupō Volcano was raised to Volcanic Alert Level 1 (minor volcanic unrest) on 20 September 2022. While no witnessed eruptive event has been recorded from Taupō, there have been seventeen episodes of volcanic unrest since 1872, with

305-597: A drop in tourism in Taupō and Rotorua. A source in San Francisco incorrectly reported that there had been 60 deaths, when there had been none. Consequentially, the government appointed a publicity officer. While Taupō is capable of very large eruptions these remain very unlikely as the majority of the 29 eruptions of various magnitudes in the last 30,000 years have been much smaller. Many have been dome-forming, which may have contributed to lake features such as Motutaiko Island and

366-598: A major component of Taupō's commercial sector. The busiest time for the industry is the high summer season around Christmas and New Year. The lake area has a temperate climate. Daily maximum temperatures recorded for Taupō range from an average of 23.3 °C in January and February to 11.2 °C in July, while the nighttime minimum temperatures range from 11.6 °C in February down to 2.2 °C in July. Rain falls in all seasons but

427-482: A much better understanding of volcanoes, including Taupō, so will be considered for context, to explain the shift in understanding from 1886 to 1888. Algernon Thomas interpreted this information to postulate that Taupō was a volcano. One of the people responsible for this lack of a survey was Sir James Hector who was Director of the New Zealand Geological Survey from 1865. When commissioned to provide

488-655: A perimeter of approximately 193 km (120 mi) and a maximum depth of 186 m (610 ft). It is drained by the Waikato River (New Zealand's longest river), and its main tributaries are the Waitahanui River , the Tongariro River , and the Tauranga Taupō River . It is a noted trout fishery with stocks of introduced brown and rainbow trout . The level of the lake is controlled by Mercury Energy ,

549-486: A predominant model for how rhyolite eruptives in these cases formed from mantle derived basalts by 20-30% assimilation of the greywacke basement and fractional crystallisation to produce a magma mush. Lake Taup%C5%8D Lake Taupō (also spelled Taupo ; Māori : Taupō-nui-a-Tia or Taupōmoana ) is a large crater lake in New Zealand 's North Island , located in the caldera of Taupō Volcano . The lake

610-425: A pyroclastic flow traveled for several hundreds of meters above the sea. A pyroclastic flow can interact with a body of water to form a large amount of mud, which can then continue to flow downhill as a lahar . This is one of several mechanisms that can create a lahar. In 1963, NASA astronomer Winifred Cameron proposed that the lunar equivalent of terrestrial pyroclastic flows may have formed sinuous rilles on

671-438: A research team at Kiel University , Germany, of pyroclastic flows moving over the water. When the reconstructed pyroclastic flow (stream of mostly hot ash with varying densities) hit the water, two things happened: the heavier material fell into the water, precipitating out from the pyroclastic flow and into the liquid; the temperature of the ash caused the water to evaporate, propelling the pyroclastic flow (now only consisting of

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732-478: Is a beech and podocarp forest with associate understory ferns being Blechnum filiforme , Asplenium flaccidum , Doodia media , Hymenophyllum demissum , Microsorum pustulatum and Dendroconche scandens , and some prominent associate shrubs being Olearia rani and Alseuosmia quercifolia . Native faunal species in the lake include northern kōura or crayfish ( Paranephrops planifrons ) and kōkopu or whitebait ( Galaxias species). The lake

793-415: Is an area of strong contrast in seismic velocity at 16 kn (30 km/h; 18 mph) depth that is postulated to be due to intruded crust from where the feed magma is evolving. Studies show large areas of partial melt below 10 km (6.2 mi) with a brittle-ductile rosk transition at approximately 6–8 km (3.7–5.0 mi) beneath the surface. For unknown as yet reasons, possibly associated with

854-551: Is greatest in winter and spring, from June to December. Taupō hosts the Lake Taupo Cycle Challenge , a cycling tour around the lake which can take anywhere between four and ten hours. Skydiving is a popular local sport and tourist attraction. Taupō also hosts the ANZCO Ironman event. Crossing the 40.2 km length of the lake is a challenge for open-water swimmers. In 2020, Michael Wells from Darwin, Australia,

915-491: Is in a caldera created mainly by a supervolcanic eruption which occurred approximately 25,600 years ago. According to geological records, the volcano has erupted 29 times in the last 30,000 years. It has ejected mostly rhyolitic lava , although Mount Tauhara formed from dacitic lava. Taupō has been active for 300,000 years with a very large event known as the Oruanui eruption occurring approximately 25,600 years ago. It

976-502: Is intended to protect Lake Taupō from volcanic activities underneath. The cliff has become a popular tourist destination with hundreds of boats and yachts visiting the spot yearly. Lake Taupō is a taonga (treasure or something special to the person) of Ngāti Tūwharetoa from the Te Arawa waka. Ngāti Tūwharetoa owns the bed of the lake and its tributaries. They grant the public free access for recreational use. Lake Taupō previously housed

1037-400: Is noted for stocks of brown trout ( Salmo trutta ) and rainbow trout ( Oncorhynchus mykiss ), introduced from Europe and California respectively in the late nineteenth century. There has also been a subsequent introduction of smelt ( Retropinnidae species) as a food for the trout. A community of sponges and associated invertebrates live around the underwater geothermal vents. Tourism is

1098-548: Is sometimes abbreviated to PDC (pyroclastic density current). Several mechanisms can produce a pyroclastic flow: Flow volumes range from a few hundred cubic meters to more than 1,000 cubic kilometres (240 cu mi). Larger flows can travel for hundreds of kilometres, although none on that scale has occurred for several hundred thousand years. Most pyroclastic flows are around one to ten cubic kilometres ( 1 ⁄ 4 – 2 + 1 ⁄ 2  cu mi) and travel for several kilometres. Flows usually consist of two parts:

1159-474: Is the namesake of the town of Taupō , which sits on a bay in the lake's northeastern shore. With a surface area of 616 km (238 sq mi), it is the largest lake by surface area in New Zealand , and the second largest freshwater lake by surface area in geopolitical Oceania after Lake Murray in Papua New Guinea . Motutaiko Island lies in the southeastern area of the lake. Lake Taupō has

1220-406: Is thrown out with great force. Such eruptions tend to be earlier in any given eruption cycle. If the volcano creates a stable plume , high in the atmosphere , the pumice and ash are blown sideways, and eventually fall to the ground, draping the landscape like snow. If the material thrown out cools more rapidly and becomes denser than the air, it cannot rise as high, and suddenly collapses back to

1281-524: The 1883 eruption of Krakatoa , supported by experimental evidence, shows that pyroclastic flows can cross significant bodies of water. However, that might be a pyroclastic surge , not flow, because the density of a gravity current means it cannot move across the surface of water. One flow reached the Sumatran coast as far as 48 kilometres (26 nautical miles) away. A 2006 BBC documentary film, Ten Things You Didn't Know About Volcanoes , demonstrated tests by

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1342-625: The Chatham Islands , 850 km (530 mi) away which included diatoms from erupted lake sediments. 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 (also known as the Taupō or Horomatangi Reef Unit Y eruption) represents

1403-527: The Hipaua steaming cliffs . GNS Science continuously monitors Taupō using a network of seismographs and GPS stations. The Horomatangi Reefs area of the lake is associated with active hydrothermal venting and high heat flow . Monitoring of a volcano situated under a lake is challenging, and an eruption might occur with little or no meaningful notice. Live data can be viewed on the GeoNet website . While volcanism

1464-540: The Horomatangi Reefs . Earthquake and tsunami hazards also exist. While most earthquakes are relatively small and associated with magma shifts, the moderate earthquakes associated with eruptions or the numerous rift -associated faults historically have produced tsunami events. The intra-rift Waihi fault , for example, has been associated with 6.5 magnitude earthquakes at recurrence intervals of between 490 and 1,380 years and at least one tsunami related to landslip at

1525-576: The Minoan eruption in the 2nd millennium BCE, the Tianchi eruption of Baekdu around 1000 CE and the 1815 eruption of Tambora ), with a Volcanic Explosivity Index rating of 7; and there appears to be a correlation, to within a few years, of a year in which the sky was red over Rome and China . The eruption devastated much of the North Island and further expanded the lake. The area was uninhabited by humans at

1586-926: The Taupō and Rotorua districts, to Whakaari / White Island , in the Bay of Plenty . Taupō began erupting about 300,000 years ago. The main eruptions that still affect the surrounding landscape are the dacitic Mount Tauhara eruption 65,000 years ago, the Oruanui eruption about 25,500 years ago, which is responsible for the shape of the modern caldera, and the Hatepe eruption , dated 232 ± 10 CE. There have been many more eruptions, with major ones every thousand years or so (see timeline of last 10,000 years of eruptions). The Oruanui eruption in particular destroyed or obscured much evidence of previous eruptive activity. Taupō Volcano has not erupted for approximately 1,800 years; however, with research beginning in 1979 and published in 2022,

1647-639: The basal flow hugs the ground and contains larger, coarse boulders and rock fragments, while an extremely hot ash plume lofts above it because of the turbulence between the flow and the overlying air, admixing and heating cold atmospheric air causing expansion and convection. Flows can deposit less than 1 meter to 200 meters in depth of loose rock fragment. The kinetic energy of the moving cloud will flatten trees and buildings in its path. The hot gases and high speed make them particularly lethal, as they will incinerate living organisms instantaneously or turn them into carbonized fossils: Testimonial evidence from

1708-427: The caldera generated during this eruption. Tephra from the eruption covered much of the central North Island with ignimbrite up to 200 m (660 ft) deep. The ignimbrite eruption(s) were possibly not as forceful as that of the later Hatepe eruption but the total impact of this eruption was somewhat greater. Most of New Zealand was affected by ashfall, with an 18 cm (7.1 in) ash layer left even on

1769-519: The Hatepe eruption from the Taupō volcano with its pyroclastic flows and vent location resulted from the work of Colin Wilson from 1980 onward. The Oruanui eruption also became better understood with for example the influence of the eruptions on the sedimentology of the region taking several decades more to unravel. Volcanology better modeled the processes of magma formation and eruption, with wider acceptance of

1830-545: The Hatepe eruption. One estimated date was 181  CE from ice cores in Greenland and Antarctica . It is possible that the meteorological phenomena described by Fan Ye in China and by Herodian in Rome were due to this eruption, which would give a date of exactly 186. However, ash from volcanic activity does not normally cross hemispheres, and radiocarbon dating by R. Sparks has put

1891-466: The Horomatangi vent, and nearby geothermal fields with associated hot springs are found north and south of the lake, for example at Rotokawa and Tūrangi . These springs are the site of occurrence of certain extremophile micro-organisms, that are capable of surviving in extremely hot environments. The volcano is considered active and is monitored by GNS Science. Much of the watershed of Lake Taupō

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1952-862: The North Island from Auckland to Napier . While Taupō has been active for about 300,000 years, explosive eruptions have been more typical in the last 42,000 years. The Oruanui eruption (also known as the Kawakawa event) of the Taupō Volcano was the world's largest known eruption in the past 70,000 years, with a Volcanic Explosivity Index of 8. It occurred around 25,500 years ago and generated approximately 430 km (100 cu mi) of pyroclastic fall deposits, 320 km (77 cu mi) of pyroclastic density current (PDC) deposits (mostly ignimbrite ) and 420 km (100 cu mi) of primary intracaldera material, equivalent to 530 km (130 cu mi) of magma . Modern Lake Taupō partly fills

2013-672: The Taupō Volcanic Zone within the Taupō Rift. This is an intra-arc rift in the eastern part of the continental Australian Plate , resulting from an oblique convergence with the Pacific Plate in the Hikurangi subduction zone . In this region the Moho discontinuity starts about 25–30 km (16–19 mi) beneath the surface beyond the modern Taupō Rift boundaries to the west and east, but there

2074-457: The Taupō Volcano has had historic vents to the south and north of the present lake, and recent seismic activity does extend beyond the lake to its north and south. To the north the border with the Maroa Caldera is ill-defined but most of the seismic activity is likely related to structures related to this caldera. While studies have identified one Taupō composition vent 20 km (12 mi) to

2135-545: The Taupō Volcano's north that extended to the Reporoa Caldera which in due course broke out into the Waikato River valley and released over a short period 2.5 km (0.60 cu mi) of water. The previous outlet of Lake Taupō was blocked, raising the lake 35 m (115 ft) above its present level, until shortly after the first smaller flood, it broke out in a huge flood, that released about 20 km (4.8 cu mi) of water. Many dates have been given for

2196-469: The data collated over the 42-year period shows that Taupō Volcano is active with periods of volcanic unrest and has been for some time. Some volcanoes within the Taupō Volcanic Zone have erupted more recently. Mount Tarawera had a moderately violent VEI-5 eruption in 1886 , and Whakaari/White Island is frequently active, erupting most recently in December 2019. Geologic studies published in 1888 following

2257-463: The date at 233 CE ± 13 (95% confidence). A 2011 C wiggle-matching paper gave the date 232 ± 5 CE. A 2021 review based on five sources reports 232 ± 10 CE. New Zealand was unpopulated at that time , so the nearest humans would have been in Australia and New Caledonia, more than 2,000 km (1,200 mi) to the west and northwest. Composition studies suggest

2318-478: The density of the current, the volcanic output rate, and the gradient of the slope. The word pyroclast is derived from the Greek πῦρ ( pýr ), meaning "fire", and κλαστός ( klastós ), meaning "broken in pieces". A name for pyroclastic flows that glow red in the dark is nuée ardente (French, "burning cloud"); this was notably used to describe the disastrous 1902 eruption of Mount Pelée on Martinique ,

2379-404: The eruption of Mount Tarawera first raised the possibility that there was a volcano under Lake Taupō, rather than the more obvious volcanoes near Mount Tongariro , to explain the likely source of the extensive surface pumice deposits of the central North Island . The Taupō Volcano erupts rhyolite , a viscous magma , with a high silica content, a feature associated with the middle portion of

2440-412: The first official report on the 1886 eruption from Tarawera his travels included Taupō. The resulting report conclusion on the cause of the eruption " I think there can be little question that it is a purely hydro-thermal phenomenon, but on a gigantic scale; that it is quite local and not of deep-seated origin... " generated controversy with some supporting this view due to their geological understanding of

2501-407: The forest over a 160 km (99 mi) distance, but this was not recognised as being due to a pyroclastic flow until 1956. The date of the most recent large eruption was first defined in the 1960s as being in the first few centuries AD based on radiocarbon dating . In the 1970s activity was assigned as far back as 330,000 years ago with radiometric dating . Further understanding of the size of

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2562-406: The ground surface than it replaced with ignimbrite. Valleys were filled with ignimbrite, evening out the shape of the land. All vegetation within the area was flattened. Loose pumice and ash deposits formed lahars down all the main rivers. The eruption further expanded the lake, which had formed after the much larger Oruanui eruption. Its new deposits also briefly created another large lake to

2623-536: The ground, forming a pyroclastic flow , hitting the surface like water from a waterfall, and spreading sideways across the land at enormous speed. When the pumice and ash settle, they are sufficiently hot to stick together as a rock called ignimbrite . Pyroclastic flows can travel hundreds of kilometres an hour. Earlier ignimbrite eruptions occurred further north than Taupō. Some of these were enormous, and two eruptions around 1.25 and 1.0 million years ago were big enough to generate an ignimbrite sheet that covered

2684-447: The lake are more than probably plugs of volcanic vents and lava-flows; and it would seem reasonable to infer that the lake owes its origin, firstly, to eruption, which was followed by a subsidence, and that subsequently some of the vents within it continued active as subaqueous volcanoes, the ejecta from which now form the comparatively level floor of the lake, having been worn away from the cones by denudation. " He deferred to others who he

2745-485: The lighter material) along on a bed of steam at an even faster pace than before. During some phases of the Soufriere Hills volcano on Montserrat, pyroclastic flows were filmed about 1 km ( 1 ⁄ 2  nmi) offshore. These show the water boiling as the flow passes over it. The flows eventually built a delta, which covered about 1 km (250 acres). Another example was observed in 2019 at Stromboli when

2806-498: The most recent being in 2019 and 2022–2023. This manifested as swarms of seismic activity and ground deformation within the caldera. The present-day magma reservoir is estimated to be at least 250 km (60 cu mi) in volume and have a melt fraction of >20%–30%. Unrest from May 1922 to January 1923 saw several thousand earthquakes, with the highest reaching magnitude 6, causing chimneys to collapse. The events were misreported internationally, which caused self-evacuations and

2867-538: The most recent major eruption of the Taupō Volcano, and occurred about 1,800 years ago. It was the most powerful eruption in the world in the last 5,000 years. The type of eruption that occurred is the most extreme volcanic hazard due to the pyroclastic flows very high mobility and heat content. It has been stated to have had an energy release equivalent to about 150 ± 50 megatons of TNT. The eruption went through several stages which were redefined in 2003 with at least 3 separate vents: The main pyroclastic flow devastated

2928-452: The north of Lake Taupō, this presumably resulted from a dyke extusion about 26,000 years ago. Recent activity to the north of the lake is assigned in terms of magma bodies, to the Poihipi volcano under Wairakei . As of 2024 it is possible that Taupō is in a state of internal instability that is susceptible to dynamic triggering by tectonic earthquakes, as the 2016 Kaikōura earthquake triggered

2989-477: The owner of the eight hydroelectric dams on the Waikato River downstream of Lake Taupō, using gates built in 1940–41. The gates are used to reduce flooding, conserve water and ensure a minimum flow of 50 m /s (1,800 cu ft/s) in the Waikato River. The resource consent allows the level of the lake to be varied between 355.85 and 357.25 metres (1,167.5 and 1,172.1 ft) above sea level. Lake Taupō

3050-467: The present high rate of rift spreading and the recent subduction of the Hikurangi Plateau this area is very productive in its surface volcanism. If the magma does not contain much gas, rhyolite tends to just form a lava dome , and such eruptions are more common. However, when mixed with gas or steam , rhyolitic eruptions can be extremely violent. The magma froths to form pumice and ash , which

3111-469: The stratovolcanoes to the south of Lake Taupō. Ferdinand von Hochstetter may well have suspected a volcano at Taupō, and certainly identified Lake Taupō as the source of the pumice deposits along the Waikato River and interpreted the lake amongst the others in the region as caused by collapse in a volcanic plateau, but was unable to investigate to exclude other possibilities. By 1864 information from Hochstetter's 1859 survey and those of Stokes and Drury

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3172-413: The surrounding area, climbing over 1,500 m (4,900 ft) to overtop the nearby Kaimanawa Ranges and Mount Tongariro , and covering the land within 80 ± 10 km (49.7 ± 6.2 mi) with ignimbrite from Rotorua to Waiouru . Only Ruapehu was high enough to divert the flow. The power of the pyroclastic flow was so strong that in some places it eroded more material off

3233-436: The temperature is still lethally high. Cold pyroclastic surges can occur when the eruption is from a vent under a shallow lake or the sea. Fronts of some pyroclastic density currents are fully dilute; for example, during the eruption of Mount Pelée in 1902, a fully dilute current overwhelmed the city of Saint-Pierre and killed nearly 30,000 people. A pyroclastic flow is a type of gravity current ; in scientific literature, it

3294-522: The time of the eruption, as New Zealand was not settled by Māori until about 1280. Possible climatic effects of the eruption would have been concentrated on the Southern Hemisphere due to the southerly position of Lake Taupō. Taupō's last known eruption occurred around 30 years later, with lava dome extrusion forming the Horomatangi Reefs , but that eruption was much smaller than the Hatepe eruption. Underwater hydrothermal activity continues near

3355-462: The time. Laurence Cussen , the District Surveyor in 1887 was unwilling to form a definite conclusion but observed " the jagged appearance of the volcanic rocks forming the steep northern and western shores leads at once to the conclusion that they were separated from the masses of which they originally formed part by some violent agency, either of eruption or subsidence. The islands and reefs in

3416-411: Was collaborating with, in the same timeframe, and as already mentioned Thomas first crystallised the possibility in the geological literature that there was a volcano under Lake Taupō as the likely source of the extensive surface pumice deposits from field work including analysis of specimens forwarded by Cussen. In 1937 it was recognised that the deposit from the Hatepe eruption had been so hot to burn

3477-419: Was published as the first geological map of the area and this shows a rim of rhyolytic deposits around all the northern two thirds of the shore line of Lake Taupō but without the full extent of the relevant surface deposits being characterised. The area did not have a further high quality geological study until after the 1886 eruption of Mount Tarawera , and the discourse following this nearby eruption resulted in

3538-484: Was recognised in the area following human occupation the recognition of the presence of a large volcano under Lake Taupō was not. Mātauranga Māori detailed that Horomātangi (Horo-matangi), a tāniwha or water monster of the lake, resided in a cave adjacent to Motutaiko Island on the south of the lake. Ernst Dieffenbach described euptives now known to have been from the Taupō Volcano in his 1843 publication on New Zealand, but like many others until 1886 assigned them to

3599-476: Was the first to breaststroke across the lake. On the north-west side of Lake Taupō on the cliffs of Mine Bay, there are Māori rock carvings created in the late 1970s by Matahi Whakataka-Brightwell and John Randall. Carved in the likeness of Ngātoro-i-rangi , a navigator who guided the Tūwharetoa and Te Arawa tribes to the Taupō area over a thousand years ago according to Māori legend . The 10-metre-high carving

3660-426: Was the world's largest known eruption over the past 70,000 years, ejecting 1170 cubic kilometres of material and causing several hundred square kilometres of surrounding land to collapse and form the caldera. The caldera later filled with water to form Lake Taupō, eventually overflowing to cause a huge outburst flood . Several later eruptions occurred over the millennia before the most recent major eruption, which

3721-404: Was traditionally dated as about 181 CE from Greenland ice-core records. Tree ring data from two studies suggests a later date of 232 CE ± 5 and this is now accepted. Known as the Hatepe eruption , it is believed to have ejected 100 cubic kilometres of material, of which 30 cubic kilometres was ejected in a few minutes. This was one of the most powerful eruptions in the last 5000 years (alongside

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