Taupō Volcano

Lake Taupō, in the centre of New Zealand's North Island, is the caldera of the Taupō Volcano, a large rhyolitic supervolcano. This huge volcano has produced two of the world's most violent eruptions in geologically recent times.

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 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 Reefs 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 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:Horomatangi Reef 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

The volcano is in the Taupō Volcanic Zone, a region of rift volcanic activity that extends from Ruapehu in the south, through 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 26,500 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).

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 had a violent VEI-5 eruption in 1886, and Whakaari/White Island is frequently active, erupting most recently in December 2019.

Rhyolitic eruptions

The Taupō Volcano erupts rhyolite, a viscous magma, with a high silica content.

If the magma does not contain much gas, rhyolite tends to just form a lava dome. However, when mixed with gas or steam, rhyolitic eruptions can be extremely violent. The magma froths to form pumice and ash, which is thrown out with great force.

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 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 eruptions

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 to Napier.

While Taupō has been active for 300,000 years, explosive eruptions became more common 65,000 years ago.

Oruanui eruption

The Oruanui eruption 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 26,500 years ago and generated approximately of pyroclastic fall deposits, of pyroclastic density current (PDC) deposits (mostly ignimbrite) and of primary intracaldera material, equivalent to of magma.

Modern Lake Taupō partly fills the caldera generated during this eruption.

Tephra from the eruption covered much of the central North Island with ignimbrite up to 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 ash layer left even on the Chatham Islands, away. Later erosion and sedimentation had long-lasting effects on the landscape, and caused the Waikato River to shift from the Hauraki Plains to its current course through the Waikato to the Tasman Sea.

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 violent eruption in the world in the last 5,000 years.

Stages of eruption

The eruption went through several stages.
*A minor eruption occurred beneath the ancestral Lake Taupō.
*A dramatic increase in activity produced a high eruption column from a second vent, and pumice was deposited over a wide area.
*Water entered the first vent and mixed with the magma, producing a white ash-rich pumice fall.
*A new vent formed and produced a dark ash- and obsidian-rich fall deposit.
*A larger eruption ensued, producing pumice over a huge area, and a small ignimbrite deposit.
*The most destructive part of the eruption then occurred. Part of the vent area collapsed, unleashing about of material, that formed a fast-moving, pyroclastic flow.
* Rhyolitic lava domes were extruded some years later, helping form the Horomatangi Reefs and Waitahanui bank. These later smaller eruptions of unknown total size also created large pumice rafts and terminated within decades of the major eruption.

The main pyroclastic flow devastated the surrounding area, climbing over to overtop the nearby Kaimanawa Ranges and Mount Tongariro, and covering the land within 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 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. The previous outlet was blocked, raising the lake above its present level until it broke out in a huge flood, flowing for more than a week at roughly 200 times the Waikato River's current rate.

Dating the Hatepe eruption

Many dates have been given for 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 the date at 233 CE ± 13 (95% confidence).
A 2011 ¹⁴C 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 to the west and northwest.

Current activity and future hazards

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 the most recent being in 2019. 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%.

The main volcanic hazard at Taupō is from a massive explosive eruption which could create a natural disaster of extreme magnitude given the size of the present magma chamber and that its last eruption was the most severe worldwide in the last 5,000 years. However some 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 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 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 th
GeoNet website

See also

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 , 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