Lake Taupō Lake Taupō (also spelled Taupo; or ) is a large crater lake in New Zealand's North Island, located in the caldera of Taupō Volcano. The lake is the namesake of the town of Taupō, which sits on a bay in the lake's northeastern shore. With ...

, in the centre of

New Zealand New Zealand () is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and List of islands of New Zealand, over 600 smaller islands. It is the List of isla ...

North Island The North Island ( , 'the fish of Māui', historically New Ulster) is one of the two main islands of New Zealand, islands of New Zealand, separated from the larger but less populous South Island by Cook Strait. With an area of , it is the List ...

, fills the

caldera A caldera ( ) is a large cauldron-like hollow that forms shortly after the emptying of a magma chamber in a volcanic eruption. An eruption that ejects large volumes of magma over a short period of time can cause significant detriment to the str ...

of the Taupō Volcano, a large

rhyolitic Rhyolite ( ) is the most silica-rich of volcanic rocks. It is generally glassy or fine-grained (aphanitic) in texture, but may be porphyritic, containing larger mineral crystals ( phenocrysts) in an otherwise fine-grained groundmass. The miner ...

supervolcano A supervolcano is a volcano that has had an eruption with a volcanic explosivity index (VEI) of 8, the largest recorded value on the index. This means the volume of deposits for such an eruption is greater than . Supervolcanoes occur whe ...

. This huge

volcano A volcano is commonly defined as a vent or fissure in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface. On Earth, volcanoes are most oft ...

has produced two of the world's most powerful eruptions in geologically recent times. The volcano is in the

Taupō Volcanic Zone The Taupō Volcanic Zone (TVZ) is a volcano, volcanic area in the North Island of New Zealand. It has been active for at least the past two million years and is still highly active. Mount Ruapehu marks its south-western end and the zone runs n ...

within the

Taupō Rift The Taupō Rift is the seismically active rift valley containing the Taupō Volcanic Zone, central North Island of New Zealand. Geology The Taupō Rift (Taupo Rift) is a intra-arc continental rift resulting from an oblique convergence in the H ...

, a region of

rift In geology, a rift is a linear zone where the lithosphere is being pulled apart and is an example of extensional tectonics. Typical rift features are a central linear downfaulted depression, called a graben, or more commonly a half-graben ...

volcanic activity that extends from Ruapehu in the south, through the

Taupō Taupō (), sometimes written Taupo, is a town located in the central North Island of New Zealand. It is situated on the edge of Lake Taupō, which is the largest freshwater lake in New Zealand. Taupō was constituted as a borough in 1953. It h ...

and

Rotorua Rotorua () is a city in the Bay of Plenty region of New Zealand's North Island. It is sited on the southern shores of Lake Rotorua, from which it takes its name. It is the seat of the Rotorua Lakes District, a territorial authorities of New Zea ...

districts, to

Whakaari / White Island Whakaari / White Island (, , lit. "the dramatic volcano"), also known as White Island or Whakaari, is an active andesite stratovolcano situated from the east coast of the North Island of New Zealand, in the Bay of Plenty. The island covers a ...

, in the

Bay of Plenty The Bay of Plenty () is a large bight (geography), bight along the northern coast of New Zealand's North Island. It stretches from the Coromandel Peninsula in the west to Cape Runaway in the east. Called ''Te Moana-a-Toitehuatahi'' (the Ocean ...

ImageSize = width:320 height:800 PlotArea = right:50 top:10 left:50 bottom:10 DateFormat = yyyy TimeAxis = orientation:vertical order:reverse Period = from:-10000 till:2050 AlignBars = early ScaleMajor = unit:year increment:1000 start:-10000 Colors = id:canvas value:rgb(1,1,0.85) BackgroundColors = canvas:canvas PlotData = width:15 color:white bar:test from:-10000 till:1200 # Pre Maori PlotData = width:15 color:yellow bar:test from:1200 till:1840 # Pre accurate PlotData = width:15 color:orange bar:test from:1840 till:2050 # Accurate PlotData = at:-9999 shift:(30,0) text: Recent eruptions of Taupō caldera at:-9999 shift:(200,0) textcolor:red text: Eruptive at:-9850 shift:(80,-1) textcolor:red fontsize:S text:(Eruptive volume) at:-9850 shift:(210,0) textcolor:red text: Index at:-9700 shift:(200,0) textcolor:red text: 6 5 4 3 2 1 at:-9460 shift:(10,-5) text: 9460 BCE East/Central Unit B at:-9460 shift:(217,2) textcolor:red fontsize:S text:(0.5 km ) at:-9460 shift:(253,4) textcolor:red fontsize:XS text:3 bar:test at:-9460 mark:(line,red) at:-9240 shift:(10,-2) text: 9240 BCE Te Kohaiakatu Pt Unit C at:-9240 shift:(217,2) textcolor:red fontsize:S text:(0.3 km ) at:-9240 shift:(253,4) textcolor:red fontsize:XS text:3 bar:test at:-9240 mark:(line,red) at:-9210 shift:(10,-10) text: 9210 BCE at:-9210 shift:(63,-10) text:

Acacia Bay Acacia Bay is a suburb of Taupō, on the western edge of Tapuaeharuru Bay Lake Taupō in New Zealand. There are four main beach areas. It is located approximately west of Taupō CBD. Demographics Acacia Bay covers and had an estimated pop ...

Unit D at:-9210 shift:(147,-10) textcolor:red fontsize:S text:(0.1 km ) at:-9210 shift:(183,-8) textcolor:red fontsize:XS text:3 bar:test at:-9210 mark:(line,red) at:-8130 shift:(10,-5) text: 8130 BCE East/Central Unit E at:-8130 shift:(226,2) textcolor:red fontsize:S text:(2 km ) at:-8130 shift:(253,4) textcolor:red fontsize:XS text:3 bar:test at:-8130 mark:(line,red) at:-5100 shift:(10,-5) text: 5100 BCE at:-5100 shift:(63,-5) text: Motutaiko Island Unit F at:-5100 shift:(212,2) textcolor:red fontsize:S text:(0.07 km ) at:-5100 shift:(253,4) textcolor:red fontsize:XS text:3 bar:test at:-5100 mark:(line,red) at:-4700 shift:(10,-5) text: 4700 BCE East/Central Unit G at:-4700 shift:(217,2) textcolor:red fontsize:S text:(0.2 km ) at:-4700 shift:(253,4) textcolor:red fontsize:XS text:3 bar:test at:-4700 mark:(line,red) at:-4100 shift:(10,-5) text: 4100 BCE Te Kohaiakatu Pt Unit H at:-4100 shift:(212,2) textcolor:red fontsize:S text:(0.08 km ) at:-4100 shift:(253,4) textcolor:red fontsize:XS text:3 bar:test at:-4100 mark:(line,red) at:-4000 shift:(10,-8) text: 4000 BCE Unit I at:-4000 shift:(87,-8) textcolor:red fontsize:S text:(0.02 km ) at:-4000 shift:(128,-6) textcolor:red fontsize:XS text:3 bar:test at:-4000 mark:(line,red) at:-3420 shift:(10,0) text: 3420 BCE Unit J at:-3420 shift:(207,2) textcolor:red fontsize:S text:(0.015 km ) at:-3420 shift:(253,4) textcolor:red fontsize:XS text:3 bar:test at:-3420 mark:(line,red) at:-3170 shift:(10,7) text: 3170 BCE Te Kohaiakatu Pt Unit K at:-3170 shift:(212,6) textcolor:red fontsize:S text:(0.35 km ) at:-3170 shift:(253,8) textcolor:red fontsize:XS text:3 bar:test at:-3170 mark:(line,red) at:-3120 shift:(10,1) text: 3120 BCE Te Kohaiakatu Pt Unit L at:-3120 shift:(171,1) textcolor:red fontsize:S text:(0.07 km ) at:-3120 shift:(212,3) textcolor:red fontsize:XS text:3 bar:test at:-3120 mark:(line,red) at:-3070 shift:(10,-5) text: 3070 BCE Te Kohaiakatu Pt Unit M at:-3070 shift:(176,-5) textcolor:red fontsize:S text:(0.2 km ) at:-3070 shift:(212,-3) textcolor:red fontsize:XS text:3 bar:test at:-3070 mark:(line,red) at:-2900 shift:(10,-3) text: 2900 BCE Te Kohaiakatu Pt Unit N at:-2900 shift:(174,-3) textcolor:red fontsize:S text:(0.15 km ) at:-2900 shift:(215,-1) textcolor:red fontsize:XS text:3 bar:test at:-2900 mark:(line,red) at:-2850 shift:(10,-9) text: 2850 BCE Te Tuhi Pt Unit O at:-2850 shift:(143,-9) textcolor:red fontsize:S text:(0.05 km ) at:-2850 shift:(184,-7) textcolor:red fontsize:XS text:3 bar:test at:-2850 mark:(line,red) at:-2800 shift:(10,-15) text: 2800 BCE Unit P at:-2800 shift:(93,-15) textcolor:red fontsize:S text:(0.05 km ) at:-2800 shift:(134,-13) textcolor:red fontsize:XS text:3 bar:test at:-2800 mark:(line,red) at:-2600 shift:(10,-11) text: 2600 BCE Te Kohaiakatu Pt Unit Q at:-2600 shift:(212,2) textcolor:red fontsize:S text:(0.15 km ) at:-2600 shift:(253,4) textcolor:red fontsize:XS text:3 bar:test at:-2600 mark:(line,red) at:-2500 shift:(10,-14) text: 2500 BCE at:-2500 shift:(63,-14) text: Motutaiko Island Unit R at:-2500 shift:(173,-14) textcolor:red fontsize:S text:(0.05 km ) at:-2500 shift:(214,-12) textcolor:red fontsize:XS text:3 bar:test at:-2500 mark:(line,red) at:-1460 shift:(10,-5) text: 1460 BCE at:-1460 shift:(63,-5) text:

Horomatangi Reef The Horomatangi Reef or reefs is a feature of Lake Taupō, in the central North Island of New Zealand. The reef is named after Horomātangi (Horo-matangi), the tāniwha or water monster of the lake, who is said to reside in a cave adjacent to t ...

s Unit S at:-1460 shift:(217,2) textcolor:red fontsize:S text:(7.5 km ) at:-1460 shift:(253,4) textcolor:red fontsize:XS text:3 bar:test at:-1460 mark:(line,red) at:-1250 shift:(10,-5) text: 1250 BCE Te Kohaiakatu Pt Unit T at:-1250 shift:(212,2) textcolor:red fontsize:S text:(0.05 km ) at:-1250 shift:(253,4) textcolor:red fontsize:XS text:3 bar:test at:-1250 mark:(line,red) at:-1050 shift:(10,-3) text: 1050 BCE at:-1050 shift:(63,-3) text: Motutaiko Island Unit U at:-1050 shift:(217,2) textcolor:red fontsize:S text:(0.1 km ) at:-1050 shift:(253,4) textcolor:red fontsize:XS text:3 bar:test at:-1050 mark:(line,red) at:-1010 shift:(10,-11) text: 1010 BCE Te Kohaiakatu Pt Unit V at:-1010 shift:(174,-11) textcolor:red fontsize:S text:(0.4 km ) at:-1010 shift:(210,-9) textcolor:red fontsize:XS text:3 bar:test at:-1010 mark:(line,red) at:-800 shift:(10,-7) text: 800 BCE Ouaha Hills Unit W at:-800 shift:(146,-7) textcolor:red fontsize:S text:(0.023 km ) at:-800 shift:(193,-5) textcolor:red fontsize:XS text:3 bar:test at:-800 mark:(line,red) at:-200 shift:(10,-5) text: 200 BCE Te Kohaiakatu Pt Unit X at:-200 shift:(212,2) textcolor:red fontsize:S text:(0.28 km ) at:-200 shift:(253,4) textcolor:red fontsize:XS text:3 bar:test at:-200 mark:(line,red) at:233 shift:(33,0) text:

Hatepe eruption The Hatepe eruption, named for the Hatepe Plinian pumice tephra layer, sometimes referred to as the Taupō eruption or Horomatangi Reef Unit Y eruption, is dated to 232 CE ± 10 and was Taupō Volcano's most recent major eruption. It is ...

Unit Y at:233 shift:(10,0) text: 233 at:233 shift:(214,2) textcolor:red fontsize:S text:(120 km ) at:233 shift:(253,4) textcolor:red fontsize:XS text:3 bar:test at:233 mark:(line,red) at:260 shift:(10,-10) text: 260 at:260 shift:(33,-10) text:

area at:260 shift:(142,-10) textcolor:red fontsize:S text:(volume unknown) bar:test at:260 mark:(line,red) at:1200 shift:(10,-5) text: Māori in NZ bar:test at:1200 mark:(line,black) at:1840 shift:(10,-5) text: European colonisation bar:test at:1840 mark:(line,black) LineData = at:260 frompos:315 tillpos:320 color:red width:2 at:233 frompos:260 tillpos:320 color:red width:2 at:-200 frompos:280 tillpos:320 color:red width:2 at:-800 frompos:300 tillpos:320 color:red width:2 at:-1010 frompos:280 tillpos:320 color:red width:2 at:-1050 frompos:280 tillpos:320 color:red width:2 at:-1250 frompos:290 tillpos:320 color:red width:2 at:-1460 frompos:270 tillpos:320 color:red width:2 at:-2500 frompos:290 tillpos:320 color:red width:2 at:-2600 frompos:280 tillpos:320 color:red width:2 at:-2800 frompos:290 tillpos:320 color:red width:2 at:-2850 frompos:290 tillpos:320 color:red width:2 at:-2900 frompos:280 tillpos:320 color:red width:2 at:-3070 frompos:280 tillpos:320 color:red width:2 at:-3120 frompos:290 tillpos:320 color:red width:2 at:-3170 frompos:280 tillpos:320 color:red width:2 at:-3420 frompos:290 tillpos:320 color:red width:2 at:-4000 frompos:290 tillpos:320 color:red width:2 at:-4100 frompos:280 tillpos:320 color:red width:2 at:-4700 frompos:280 tillpos:320 color:red width:2 at:-5100 frompos:290 tillpos:320 color:red width:2 at:-8130 frompos:270 tillpos:320 color:red width:2 at:-9210 frompos:280 tillpos:320 color:red width:2 at:-9240 frompos:270 tillpos:320 color:red width:2 at:-9460 frompos:270 tillpos:320 color:red width:2

History

Taupō began erupting about 300,000 years ago. The main eruptions that still affect the surrounding landscape are the

dacitic Dacite () is a volcanic rock formed by rapid solidification of lava that is high in silica and low in alkali metal oxides. It has a fine-grained (aphanitic) to porphyritic texture and is intermediate in composition between andesite and rhyolite. ...

Mount Tauhara eruption 65,000 years ago, the

Oruanui eruption The Oruanui eruption (also known as the Kawakawa eruption or Kawakawa/Oruanui event) of Taupō Volcano in New Zealand around 25,700 years before present was the world's most recent supereruption, and its largest phreatomagmatic eruption charact ...

about 25,500 years ago, which is responsible for the shape of the modern caldera, and the

, 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, 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 Mount Tarawera is a volcano on the North Island of New Zealand within the older but volcanically productive Ōkataina Caldera. Located 24 kilometres southeast of Rotorua, it consists of a series of rhyolitic lava domes that were fissured ...

had a moderately violent VEI-5 eruption in

1886 Events January * January 1 – Upper Burma is formally annexed to British rule in Burma, British Burma, following its conquest in the Third Anglo-Burmese War of November 1885. * January 5–January 9, 9 – Robert Louis Stevenson ...

, and

Whakaari/White Island Whakaari / White Island (, , lit. "the dramatic volcano"), also known as White Island or Whakaari, is an active andesite stratovolcano situated from the east coast of the North Island of New Zealand, in the Bay of Plenty. The island covers a ...

is frequently active, erupting most recently in December 2019. Geologic studies published in 1888 following 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 Mount Tongariro (; ) is a compound volcano in the Taupō Volcanic Zone of the North Island of New Zealand. It is located to the southwest of Lake Taupō, and is the northernmost of the three active volcanoes that dominate the landscape of ...

, to explain the likely source of the extensive surface

pumice Pumice (), called pumicite in its powdered or dust form, is a volcanic rock that consists of extremely vesicular rough-textured volcanic glass, which may or may not contain crystals. It is typically light-colored. Scoria is another vesicula ...

deposits of the central North Island.

Geology

The Taupō Volcano erupts

rhyolite Rhyolite ( ) is the most silica-rich of volcanic rocks. It is generally glassy or fine-grained (aphanitic) in texture (geology), texture, but may be porphyritic, containing larger mineral crystals (phenocrysts) in an otherwise fine-grained matri ...

, a viscous

magma Magma () is the molten or semi-molten natural material from which all igneous rocks are formed. Magma (sometimes colloquially but incorrectly referred to as ''lava'') is found beneath the surface of the Earth, and evidence of magmatism has also ...

, with a high

silica Silicon dioxide, also known as silica, is an oxide of silicon with the chemical formula , commonly found in nature as quartz. In many parts of the world, silica is the major constituent of sand. Silica is one of the most complex and abundant f ...

content, a feature associated with the middle portion of the Taupō Volcanic Zone within the Taupō Rift. This is an intra-arc rift in the eastern part of the continental

Australian Plate The Australian plate is or was a major tectonic plate in the eastern and, largely, southern hemispheres. Originally a part of the ancient continent of Gondwana, Australia remained connected to India and Antarctica until approximately when Indi ...

, resulting from an oblique convergence with the Pacific Plate in the Hikurangi subduction zone. In this region the

Moho discontinuity Moho may refer to: Birds * Moho (genus), ''Moho'' (genus), an extinct genus of birds in the family Mohoidae * The Hawaiian name of the Hawaiian rail, an extinct species * The Māori name of the North Island takahē, an extinct species * A local na ...

starts about beneath the surface beyond the modern Taupō Rift boundaries to the west and east, but there is an area of strong contrast in seismic velocity at 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 with a brittle-ductile rock transition at approximately beneath the surface. For unknown as yet reasons, possibly associated with the present high rate of rift spreading and the recent subduction of the

Hikurangi Plateau The Hikurangi Plateau is an oceanic plateau in the South Pacific Ocean east of the North Island of New Zealand. It is part of a large igneous province (LIP) together with Manihiki and Ontong Java, now located and north of Hikurangi respect ...

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 In volcanology, a lava dome is a circular, mound-shaped protrusion resulting from the slow extrusion of viscous lava from a volcano. Dome-building eruptions are common, particularly in convergent plate boundary settings. Around 6% of eruptions ...

, and such eruptions are more common. However, when mixed with gas or

steam Steam is water vapor, often mixed with air or an aerosol of liquid water droplets. This may occur due to evaporation or due to boiling, where heat is applied until water reaches the enthalpy of vaporization. Saturated or superheated steam is inv ...

, rhyolitic eruptions can be extremely violent. The magma froths to form

and ash, which 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 An atmosphere () is a layer of gases that envelop an astronomical object, held in place by the gravity of the object. A planet retains an atmosphere when the gravity is great and the temperature of the atmosphere is low. A stellar atmosph ...

, 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 the ground, forming a

pyroclastic flow A pyroclastic flow (also known as a pyroclastic density current or a pyroclastic cloud) is a fast-moving current of hot gas and volcanic matter (collectively known as tephra) that flows along the ground away from a volcano at average speeds of b ...

, 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 Ignimbrite is a type of volcanic rock, consisting of hardened tuff. Ignimbrites form from the deposits of pyroclastic flows, which are a hot suspension of particles and gases flowing rapidly from a volcano, driven by being denser than the surrou ...

. Pyroclastic flows can travel hundreds of kilometres an hour.

Earlier eruptions

Lake taupo landsat volcanic features vents

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 the North Island from

Auckland Auckland ( ; ) is a large metropolitan city in the North Island of New Zealand. It has an urban population of about It is located in the greater Auckland Region, the area governed by Auckland Council, which includes outlying rural areas and ...

to Napier. While Taupō has been active for about 300,000 years, explosive eruptions have been more typical in the last 42,000 years.

Oruanui eruption

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 The volcanic explosivity index (VEI) is a scale used to measure the size of explosive volcanic eruptions. It was devised by Christopher G. Newhall of the United States Geological Survey and Stephen Self in 1982. Volume of products, eruption c ...

of 8. It occurred around 25,500 years ago and generated approximately of

pyroclastic fall A pyroclastic fall deposit is a uniform deposit of material which has been ejected from a volcanic eruption or plume such as an ash fall or tuff. Pyroclastic fallout deposits are a result of: # Ballistic transport of ejecta such as volcanic bloc ...

deposits, of

pyroclastic density current A pyroclastic flow (also known as a pyroclastic density current or a pyroclastic cloud) is a fast-moving current of hot volcanic gas, gas and volcanic matter (collectively known as tephra) that flows along the ground away from a volcano at average ...

(PDC) deposits (mostly

) and of primary intracaldera material, equivalent to of

. Modern

partly fills the

generated during this eruption.

Tephra Tephra is fragmental material produced by a Volcano, volcanic eruption regardless of composition, fragment size, or emplacement mechanism. Volcanologists also refer to airborne fragments as pyroclasts. Once clasts have fallen to the ground, ...

from the eruption covered much of the central

with ignimbrite up to deep. The ignimbrite eruption(s) were possibly not as forceful as that of the later

but the total impact of this eruption was somewhat greater. Most of New Zealand was affected by ashfall, with an ash layer left even on the

Chatham Islands The Chatham Islands ( ; Moriori language, Moriori: , 'Misty Sun'; ) are an archipelago in the Pacific Ocean about east of New Zealand's South Island, administered as part of New Zealand, and consisting of about 10 islands within an approxima ...

, away which included

diatom A diatom (Neo-Latin ''diatoma'') is any member of a large group comprising several Genus, genera of algae, specifically microalgae, found in the oceans, waterways and soils of the world. Living diatoms make up a significant portion of Earth's B ...

s from erupted lake sediments. Later

erosion Erosion is the action of surface processes (such as Surface runoff, water flow or wind) that removes soil, Rock (geology), rock, or dissolved material from one location on the Earth's crust#Crust, Earth's crust and then sediment transport, tran ...

and

sedimentation Sedimentation is the deposition of sediments. It takes place when particles in suspension settle out of the fluid in which they are entrained and come to rest against a barrier. This is due to their motion through the fluid in response to th ...

had long-lasting effects on the landscape, and caused the

Waikato River The Waikato River is the longest river in New Zealand, running for through the North Island. It rises on the eastern slopes of Mount Ruapehu, joining the Tongariro River system and flowing through Lake Taupō, New Zealand's largest lake. It th ...

to shift from the

Hauraki Plains The Hauraki Plains are a geographical area located in the northern North Island of New Zealand, at the lower (northern) end of the Thames Valley, New Zealand, Thames Valley. They are located 75 kilometres south-east of Auckland, at the foot of ...

to its current course through the Waikato to the

Tasman Sea The Tasman Sea is a marginal sea of the South Pacific Ocean, situated between Australia and New Zealand. It measures about across and about from north to south. The sea was named after the Dutch explorer Abel Janszoon Tasman, who in 1642 wa ...

Hatepe eruption

The Hatepe eruption (also known as the Taupō or Horomatangi Reef Unit Y eruption) represents 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

s very high mobility and heat content. It has been stated to have had an energy release equivalent to about 150 ± 50 megatons of TNT.

Stages of eruption

The eruption went through several stages which were redefined in 2003 with at least 3 separate vents: #A minor eruption occurred beneath the ancestral Lake Taupō lasting hours, and producing of fine ash. #A dramatic increase in activity produced a high

eruption column An eruption column or eruption plume is a cloud of super-heated Volcanic ash, ash and tephra suspended in volcanic gas, gases emitted during an explosive eruption, explosive volcanic eruption. The volcanic materials form a vertical column or Plu ...

from a second vent, and dry ash. #A vent erupted mainly wet phreatoplinian ash but some dry magmatic ash to a total of over tens of hours. #Either a short break occurred or two vents became active at the same time with one producing a wet dark ash- and

obsidian Obsidian ( ) is a naturally occurring volcanic glass formed when lava extrusive rock, extruded from a volcano cools rapidly with minimal crystal growth. It is an igneous rock. Produced from felsic lava, obsidian is rich in the lighter element ...

-rich fall deposit, the Rotongaio fine phreatoplinian ash. At the end of the last phase or beginning of this there was a period of heavy rainfall. #A larger dry eruption ensued, which erupted ash/pumice over a huge area, over up to 17 hours, before partial column collapse with as many as eleven dry pyroclastic flow density currents resulting in of local

deposits to the east of the present lake. #The most destructive part of the eruption then occurred. Part of the vent area collapsed, as part of a process that unleashed about of material, that formed a fast-moving, pyroclastic flow lasting no more than 15 minutes. #

Rhyolitic Rhyolite ( ) is the most silica-rich of volcanic rocks. It is generally glassy or fine-grained (aphanitic) in texture, but may be porphyritic, containing larger mineral crystals ( phenocrysts) in an otherwise fine-grained groundmass. The miner ...

s were extruded some years later, helping form the Horomatangi

Reef A reef is a ridge or shoal of rock, coral, or similar relatively stable material lying beneath the surface of a natural body of water. Many reefs result from natural, abiotic component, abiotic (non-living) processes such as deposition (geol ...

s and

Waitahanui Waitahanui is a village in the Taupō District, Waikato, Waikato region, New Zealand. The village is on the eastern shore of Lake Taupō, south of the district seat of Taupō. Waitahanui Marae and Pākira meeting house is a meeting place for ...

bank. These later smaller eruptions of unknown total size also created large

pumice raft A pumice raft is a floating raft of pumice created by some eruptions of submarine volcanoes or coastal subaerial volcanoes. Pumice rafts have unique characteristics, such as the highest surface-area-to-volume ratio known for any rock type, long ...

s and terminated within decades of the major eruption. The main pyroclastic flow devastated the surrounding area, climbing over to overtop the nearby

Kaimanawa Ranges The Kaimanawa Range, officially called the Kaimanawa Mountains since 16 July 2020, is a range of mountains in the central North Island of New Zealand. They extend for 50 kilometres in a northeast–southwest direction through largely uninhabited ...

and

, and covering the land within with

from

Waiouru Waiouru is a small town in the Ruapehu District, in New Zealand's Manawatū-Whanganui region. It is located on the south-eastern North Island Volcanic Plateau, north of Palmerston North and 25 kilometres south-east of Mount Ruapehu. The tow ...

. Only Ruapehu was high enough to divert the flow. The power of the pyroclastic flow was so strong that in some places it

eroded Erosion is the action of surface processes (such as water flow or wind) that removes soil, rock, or dissolved material from one location on the Earth's crust and then transports it to another location where it is deposited. Erosion is disti ...

more material off 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

lahar A lahar (, from ) is a violent type of mudflow or debris flow composed of a slurry of Pyroclastic rock, pyroclastic material, rocky debris and water. The material flows down from a volcano, typically along a valley, river valley. Lahars are o ...

s 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 the Taupō Volcano's north that extended to the Reporoa Caldera which in due course broke out into the

valley and released over a short period of water. The previous outlet of Lake Taupō was blocked, raising the lake above its present level, until shortly after the first smaller flood, it broke out in a huge flood, that released about of water.

Dating the Hatepe eruption

Many dates have been given for the Hatepe eruption. One estimated date was 181 CE from

ice core An ice core is a core sample that is typically removed from an ice sheet or a high mountain glacier A glacier (; or ) is a persistent body of dense ice, a form of rock, that is constantly moving downhill under its own weight. A glacier ...

s in

Greenland Greenland is an autonomous territory in the Danish Realm, Kingdom of Denmark. It is by far the largest geographically of three constituent parts of the kingdom; the other two are metropolitan Denmark and the Faroe Islands. Citizens of Greenlan ...

and

Antarctica Antarctica () is Earth's southernmost and least-populated continent. Situated almost entirely south of the Antarctic Circle and surrounded by the Southern Ocean (also known as the Antarctic Ocean), it contains the geographic South Pole. ...

. It is possible that the

meteorological Meteorology is the scientific study of the Earth's atmosphere and short-term atmospheric phenomena (i.e. weather), with a focus on weather forecasting. It has applications in the military, aviation, energy production, transport, agriculture ...

phenomena described by Fan Ye in China and by

Herodian Herodian or Herodianus () of Syria, sometimes referred to as "Herodian of Antioch" (c. 170 – c. 240), was a minor Roman civil servant who wrote a colourful history in Greek titled ''History of the Empire from the Death of Marcus'' (τῆς με ...

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 the date at 233 CE ± 13 (95% confidence). A 2011 ¹⁴C

wiggle-matching Wiggle matching, also known as ''carbon–14 wiggle-match dating'' (WMD) is a dating method that uses the non-linear relationship between 14C age and calendar age to match the shape of a series of closely sequentially spaced 14C dates with the ...

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 to the west and northwest.

Current activity and future hazards

ISS063-E-88152 - View of the North Island of New Zealand

Composition studies suggest 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 to 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 Wairakei is a small settlement and Geothermal activity, geothermal area 8-kilometres (5 mi) north of Taupō, in the centre of the North Island of New Zealand, on the Waikato River. It is part of the Taupō Volcanic Zone and features several nat ...

. 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 The 2016 Kaikōura earthquake was a 7.8 earthquake in the South Island of New Zealand that occurred two minutes after midnight on 14 November 2016 Time in New Zealand, NZDT (11:02 on 13 November UTC). earthquake rupture, Ruptures occurred on ...

triggered 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 An earthquakealso called a quake, tremor, or tembloris the shaking of the Earth's surface resulting from a sudden release of energy in the lithosphere that creates seismic waves. Earthquakes can range in intensity, from those so weak they ...

activity with lakeside

slumping Slumping is a technique in which items are made in a kiln by means of shaping glass over molds at high temperatures. The slumping of a pyrometric cone is often used to measure temperature in a kiln. Technique Slumping glass is a highly techni ...

and

inundation A flood is an overflow of water ( or rarely other fluids) that submerges land that is usually dry. In the sense of "flowing water", the word may also be applied to the inflow of the tide. Floods are of significant concern in agriculture, civi ...

from a small

tsunami A tsunami ( ; from , ) is a series of waves in a water body caused by the displacement of a large volume of water, generally in an ocean or a large lake. Earthquakes, volcanic eruptions and underwater explosions (including detonations, ...

and ground deformation. The

Volcanic Alert Level In New Zealand, Volcano Alert Bulletins (VABs) are the official source of warnings and alerts including current Volcanic Alert Level (VAL), intended to inform stakeholder agencies, authorities, and the public about emergencies so they can take ac ...

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 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 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 a drop in tourism in Taupō and Rotorua. A source in

San Francisco San Francisco, officially the City and County of San Francisco, is a commercial, Financial District, San Francisco, financial, and Culture of San Francisco, cultural center of Northern California. With a population of 827,526 residents as of ...

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 the

s. 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

-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 Landslides, also known as landslips, rockslips or rockslides, are several forms of mass wasting that may include a wide range of ground movements, such as rockfalls, mudflows, shallow or deep-seated slope failures and debris flows. Landslide ...

at the

Hipaua steaming cliffs The Hipaua steaming cliffs are a geological feature on the southern shores of Lake Taupō near Little Waihi, which also has hot springs associated with the Hipaua geothermal area. Geology Geothermal The long steaming cliffs are part of a ge ...

GNS Science GNS Science (), officially registered as the Institute of Geological and Nuclear Sciences Limited, is a New Zealand Crown Research Institute. It focuses on geology, geophysics (including seismology and volcanology), and nuclear science (partic ...

continuously monitors Taupō using a network of

seismograph A seismometer is an instrument that responds to ground displacement and shaking such as caused by quakes, volcanic eruptions, and explosions. They are usually combined with a timing device and a recording device to form a seismograph. The out ...

s and

GPS The Global Positioning System (GPS) is a satellite-based hyperbolic navigation system owned by the United States Space Force and operated by Mission Delta 31. It is one of the global navigation satellite systems (GNSS) that provide geol ...

stations. The Horomatangi Reefs area of the lake is associated with active

hydrothermal vent Hydrothermal vents are fissures on the seabed from which geothermally heated water discharges. They are commonly found near volcanically active places, areas where tectonic plates are moving apart at mid-ocean ridges, ocean basins, and hot ...

ing 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 th
GeoNet website

History of geological understanding

1859 Hochstetter map The Southern Part of the Province of Auckland

While volcanism was recognised in the area following human occupation the recognition of the presence of a large volcano under Lake Taupō was not.

Mātauranga Māori Mātauranga (literally ''Māori knowledge'') is a modern term for the traditional knowledge of the Māori people of New Zealand. Māori traditional knowledge is Interdisciplinarity, multi-disciplinary and Logical holism, holistic, and there is c ...

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 Johann Karl Ernst Dieffenbach (27 January 1811 – 1 October 1855), also known as Ernest Dieffenbach, was a German physician, geologist and naturalist, the first trained scientist to live and work in New Zealand, where he travelled widely under th ...

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 the stratovolcanoes to the south of Lake Taupō.

Ferdinand von Hochstetter Christian Gottlieb Ferdinand Ritter von Hochstetter (30 April 1829 – 18 July 1884) was a Germany, German-Austrians, Austrian geologist. In 1857 he was appointed geologist on the Austrian Novara expedition to New Zealand, collecting natural his ...

may well have suspected a volcano at Taupō, and certainly identified Lake Taupō as the source of the pumice deposits along the

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 Drury may refer to: Places * Drury, New Zealand, a town * Drury, a village near Buckley, Flintshire, Wales * Drury, Kansas, United States, an unincorporated community * Drury, a village in Florida, Massachusetts, United States * Drury, Missouri, ...

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 The 1886 eruption of Mount Tarawera was a violent volcanic eruption that occurred in the early hours of 10 June 1886 at Mount Tarawera, near Rotorua on New Zealand's North Island. The eruption reached an estimated volcanic explosivity index (VE ...

, and the discourse following this nearby eruption resulted in 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 Sir Algernon Phillips Withiel Thomas (3 June 1857 – 28 December 1937) was a New Zealand university professor, geologist, biologist and educationalist. He was born in Birkenhead, Cheshire, England in 1857 and died in Auckland, New Zealand in ...

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 Sir James Hector (16 March 1834 – 6 November 1907) was a Scottish-New Zealand geologist, naturalist, and surgeon who accompanied the Palliser Expedition as a surgeon and geologist. He went on to have a lengthy career as a government employed ...

who was Director of the New Zealand Geological Survey from 1865. When commissioned to provide 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 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 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 was collaborating with, in the same timeframe, and as already mentioned

Thomas Thomas may refer to: People * List of people with given name Thomas * Thomas (name) * Thomas (surname) * Saint Thomas (disambiguation) * Thomas Aquinas (1225–1274) Italian Dominican friar, philosopher, and Doctor of the Church * Thomas the A ...

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 the forest over a 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 Radiocarbon dating (also referred to as carbon dating or carbon-14 dating) is a method for Chronological dating, determining the age of an object containing organic material by using the properties of carbon-14, radiocarbon, a radioactive Isotop ...

. In the 1970s activity was assigned as far back as 330,000 years ago with

radiometric dating Radiometric dating, radioactive dating or radioisotope dating is a technique which is used to Chronological dating, date materials such as Rock (geology), rocks or carbon, in which trace radioactive impurity, impurities were selectively incorporat ...

. Further understanding of the size of the Hatepe eruption from the Taupō volcano with its pyroclastic flows and vent location resulted from the work of

Colin Wilson Colin Henry Wilson (26 June 1931 – 5 December 2013) was an English existentialist philosopher-novelist. He also wrote widely on true crime, mysticism and the paranormal, eventually writing more than a hundred books. Wilson called his p ...

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 modelled the processes of magma formation and eruption, with wider acceptance of a predominant model for how rhyolite eruptives in these cases formed from mantle derived basalts by 20-30% assimilation of the

greywacke Greywacke or graywacke ( ) is a variety of sandstone generally characterized by its hardness (6–7 on Mohs scale), dark color, and Sorting (sediment), poorly sorted angular grains of quartz, feldspar, and small rock fragments or sand-size Lith ...

basement and fractional crystallisation to produce a magma mush.

Notes

References

External links

Lake-floor relief map
from . Same data exists in {{Cite journal , last=Rowe , first=Dave , author2=James, Gavin , author3=Macaulay, Gavin , author4=Shankar, Ude , date=October 2002 , url=http://www.niwascience.co.nz/pubs/wa/ma/10-3/tools , title=High-tech tools for tackling fisheries problems in lakes , journal=Water & Atmosphere , volume=10 , issue=3 , pages=24–25 , publisher=

NIWA The National Institute of Water and Atmospheric Research or NIWA (), is a Crown Research Institute of New Zealand. Established in 1992, NIWA conducts research across a broad range of disciplines in the environmental sciences. It also maintai ...

, access-date=16 March 2008 , url-status=dead , archive-url=https://web.archive.org/web/20080502191322/http://www.niwascience.co.nz/pubs/wa/ma/10-3/tools , archive-date=2 May 2008 Holocene calderas Pleistocene calderas Taupō Volcanic Zone Geology of New Zealand Calderas of New Zealand VEI-8 volcanoes VEI-7 volcanoes VEI-6 volcanoes Supervolcanoes Landforms of Waikato Tsunamis in New Zealand Lists of volcanic eruptions Lake Taupō Volcanoes of Waikato