New Zealand Volcanoes Explained: Ruapehu, Whakaari, Tongariro, Taupō and the Pacific Ring of Fire

New Zealand Volcanoes Overview

New Zealand’s active volcanoes belong to several distinct volcanic environments. They range from frequently
active cone volcanoes to enormous rhyolitic calderas whose most powerful eruptions occur thousands or tens of
thousands of years apart.

Most volcanic activity during approximately the last 1.6 million years has occurred within the
Taupō Volcanic Zone. This elongated region extends from Whakaari/White Island in the northeast
through Rotorua and Lake Taupō to Ruapehu in the southwest.

The zone contains:

• Frequently active stratovolcanoes such as Ruapehu and Tongariro–Ngāuruhoe
• The offshore cone volcano Whakaari/White Island
• The large active Taupō and Okataina caldera systems
• Rotorua and other older caldera centres
• Numerous geothermal fields, hot springs, geysers and fumaroles
• Faults and rift structures created by crustal extension

North of New Zealand, the same plate-boundary system continues through the Kermadec Islands and a long chain of
submarine volcanoes. Some of these underwater centres have produced enormous pumice rafts and powerful explosive
eruptions despite being largely invisible from land.

The Auckland region presents a contrasting form of volcanism. Instead of one large central volcano, magma has
erupted through many separate vents, creating cones, explosion craters, lava flows and islands across the urban
landscape.

Why Is New Zealand So Volcanic?

New Zealand lies astride an active boundary between two enormous pieces of Earth’s lithosphere: the
Pacific Plate and the Australian Plate.

Plate motion does not occur in the same way along the entire length of the country. Northeast of the South Island
and beneath the North Island, the Pacific Plate descends westward beneath the Australian Plate. In the South
Island, plate motion is dominated by oblique collision and sideways movement along the Alpine Fault. Farther
southwest, the direction of subduction reverses.

The North Island subduction system generates magma by carrying water-rich oceanic crust and sediment into the
mantle. Fluids released from the descending slab promote partial melting in the hotter mantle above it.

Magma then rises through fractures in the crust. Some reaches the surface quickly as basaltic or andesitic magma,
while some remains underground, cools, crystallises, mixes and evolves into silica-rich rhyolite.

This process explains why New Zealand contains both steep andesitic cone volcanoes and enormous rhyolitic caldera
systems within the same broad volcanic zone.

Pacific and Australian Plate Tectonics

East of the North Island, the Pacific seafloor descends along the Hikurangi subduction margin.
The plate boundary continues northeastward into the Kermadec Trench and ultimately connects with the Tonga
subduction system.

The descending Pacific Plate can be traced beneath the North Island through the distribution of earthquakes.
Shallow earthquakes occur near the plate interface and crustal faults, while deeper earthquakes mark the slab as
it sinks into the mantle.

The active volcanic front lies inland from the trench because magma generation becomes especially effective at
depth beneath the central North Island.

Why the Volcanoes Are West of the Trench

Volcanoes do not usually form directly above the point where one plate first begins to descend. The slab must
reach sufficient depth for water-bearing minerals to break down and release fluids into the mantle wedge.

As a result, volcanic arcs commonly occur roughly parallel to, but tens or hundreds of kilometres inland from,
their associated ocean trench.

The Hikurangi–Kermadec System

The Hikurangi margin east of the North Island transitions northward into the deeper Kermadec Trench. Together,
these boundaries form one of the major convergent plate systems of the southwest Pacific.

Volcanic activity above this subduction zone continues from the central North Island through Whakaari and the
submarine volcanoes of the Kermadec Arc.

Subduction, Back-Arc Extension and Magma

Subduction alone does not fully explain the Taupō Volcanic Zone. The crust behind the volcanic arc is also being
stretched and thinned.

This process is called back-arc extension. As the subducting Pacific Plate retreats or rolls
back, the overriding crust can be pulled apart. Faults form, blocks of crust subside and magma gains additional
pathways toward the surface.

The Taupō Rift is the active zone of extension running through much of the central volcanic region. Earthquakes,
ground deformation and geothermal systems reflect the continuing interaction between tectonic stretching and
magmatism.

Why the Central Taupō Volcanic Zone Is So Explosive

The central part of the zone contains unusually productive rhyolitic magma systems. Heat supplied by basaltic
magma from the mantle causes melting, crystallisation and chemical evolution within the crust.

Rhyolite contains more silica than basalt and is far more viscous. Gas can become trapped as the magma rises,
allowing pressure to build until explosive fragmentation occurs.

Large eruptions may produce:

• High eruption columns
• Widespread pumice and ashfall
• Pyroclastic density currents
• Ignimbrite sheets
• Caldera collapse
• Long-lasting disruption to landscapes and waterways

Major Volcanic Regions of New Zealand

The Taupō Volcanic Zone

The Taupō Volcanic Zone is approximately 350 kilometres long and up to about 100 kilometres
wide. It extends from Ruapehu in the southwest through Lake Taupō and Rotorua to Whakaari in the northeast.

It is one of the most productive zones of young silicic volcanism in the world. Its volcanoes have generated
immense volumes of rhyolite, pumice, ash and ignimbrite during the last several hundred thousand years.

Southern Taupō Volcanic Zone

The southern end contains the andesitic cone volcanoes Ruapehu and Tongariro–Ngāuruhoe. Their eruptions are
generally smaller than the largest caldera eruptions but occur more frequently.

Hazards include:

• Explosive crater eruptions
• Ballistic rocks
• Ashfall
• Lahars
• Pyroclastic density currents
• Volcanic gases

Central Taupō Volcanic Zone

Between Taupō and Rotorua lie several major caldera systems and geothermal fields. The region has produced some
of Earth’s largest eruptions during the geologically recent past.

Taupō and Okataina remain active magma systems. Rotorua, Kapenga, Whakamaru, Mangakino, Maroa and other centres
record repeated phases of caldera formation and volcanic renewal.

Northern Taupō Volcanic Zone

The northern zone narrows toward the Bay of Plenty and continues offshore through Whakaari and the submarine
volcanic arc.

Much of the crust in this area is actively extending. Geothermal fields, volcanic islands and offshore vents
reveal the transition between continental back-arc volcanism and the oceanic Kermadec Arc.

The Kermadec Volcanic Arc

North of Whakaari, the volcanic arc continues beneath the Pacific Ocean as the
Kermadec volcanic arc.

Most Kermadec volcanoes are submerged. Only a small number rise above sea level as islands, including Raoul
Island, the largest of the Kermadec Islands.

The submerged arc contains stratovolcanoes, calderas, lava domes, hydrothermal vents and active eruptive centres.
Some are comparable in size to major land volcanoes despite being hidden beneath kilometres of seawater.

Havre Submarine Eruption

The 2012 Havre eruption produced an enormous raft of floating pumice in the southwest Pacific. Detailed mapping
later revealed lava, ash and pumice deposits across the submarine caldera.

The eruption demonstrated that powerful silicic activity can occur far offshore without being directly witnessed.
Satellites and ships detected the floating products after the eruption had begun.

Raoul Island

Raoul Island is the emergent summit of a large caldera volcano. It contains crater lakes, fumaroles and evidence
of explosive eruptions.

Activity in 2006 included a sudden eruption near Green Lake that killed a Department of Conservation worker.
The event reinforced the danger of hydrothermal and phreatic explosions on remote volcanic islands.

The Kermadec Arc will be explored in greater detail in Part 2 under New Zealand’s offshore and submarine
volcanoes.

The Auckland Volcanic Field

The Auckland Volcanic Field lies directly beneath New Zealand’s largest urban area. It contains
approximately 53 recognised volcanic centres, although the number can change as geological mapping identifies
buried or overlapping vents.

Unlike Ruapehu or Teide-style central volcanoes, Auckland is a
monogenetic volcanic field. Each small volcano usually erupts during one relatively short
episode and is then unlikely to erupt again.

The next eruption would therefore probably open at a new location rather than from the summit of an existing
cone.

Auckland Volcanic Landforms

• Scoria and cinder cones
• Explosion craters and maars
• Tuff rings
• Lava flows
• Lava caves
• Volcanic islands

Rangitoto

Rangitoto is the youngest and largest volcanic centre in the Auckland field. Its broad basaltic shield and
symmetrical summit cones dominate the entrance to Waitematā Harbour.

Eruptions occurred roughly six centuries ago, within the period of Māori settlement. Rangitoto produced a much
larger volume of lava than most other Auckland vents.

Why Auckland Volcanism Is High Risk

An eruption could begin beneath a suburb, harbour, motorway, industrial zone or essential utility corridor.
Even a comparatively small basaltic event could cause enormous social and economic disruption.

Potential hazards include:

• Earthquake swarms and ground cracking
• Phreatomagmatic explosions where magma encounters groundwater or seawater
• Ballistic fragments
• Ashfall
• Lava flows
• Volcanic gases
• Closure of roads, ports and airports
• Long-term displacement from buried neighbourhoods

A comprehensive Auckland section will appear in Part 2.

North Island Versus South Island Volcanism

Nearly all of New Zealand’s currently active volcanoes occur in or north of the North Island. This distribution
reflects the changing geometry of the plate boundary.

North Island

Beneath the North Island, the Pacific Plate descends beneath the Australian Plate. This subduction creates mantle
melting and feeds the Taupō Volcanic Zone and Kermadec Arc.

South Island

In the South Island, the dominant plate boundary is the Alpine Fault. Here the plates move past one another while
also colliding and uplifting the Southern Alps.

This tectonic environment produces major earthquakes and rapid mountain building but little modern arc
volcanism.

Ancient South Island Volcanoes

The South Island contains remnants of much older volcanic systems, including the deeply eroded volcanoes that
formed Banks Peninsula near Christchurch and the Dunedin volcanic complex.

These landscapes are geologically important but are not part of the present Taupō–Kermadec active volcanic arc.

How Many Active Volcanoes Does New Zealand Have?

The total depends on the definition used and whether offshore volcanoes within New Zealand’s maritime territory
are included.

The Smithsonian Global Volcanism Program lists 23 New Zealand volcanoes with confirmed Holocene activity.
National monitoring groups classify volcanic systems according to their geological histories, current unrest and
potential to erupt again.

Important active or potentially active systems include:

• Whakaari/White Island
• Ruapehu
• Tongariro
• Ngāuruhoe
• Taupō
• Okataina
• Rotorua
• Taranaki Maunga
• Auckland Volcanic Field
• Tūhua/Mayor Island
• Raoul Island
• Multiple submarine Kermadec volcanoes

“Active” does not mean continuously erupting. Taupō can remain quiet for centuries while retaining a large active
magmatic system. Whakaari may display persistent gas and hydrothermal activity between eruptive episodes.

Types of New Zealand Volcanoes

New Zealand contains several fundamentally different types of volcano. Each creates a different combination of
eruption frequency, warning signs and hazards.

Stratovolcanoes

Ruapehu, Tongariro, Ngāuruhoe, Taranaki and Whakaari are cone-building volcanic systems composed of lava,
fragmented rock and eruption deposits.

These volcanoes may produce repeated moderate eruptions, crater explosions, ashfall, pyroclastic flows and
lahars.

Caldera Volcanoes

Taupō, Okataina and Rotorua are broad volcanic systems rather than simple cones. Their vents may open across
areas many kilometres wide.

Eight major caldera volcanoes have been identified in the central Taupō Volcanic Zone between Rotorua and Taupō.

Monogenetic Volcanic Fields

Auckland and parts of Northland contain fields of small volcanoes that generally erupt only once at a given vent.
Future activity is expected to create a new cone or crater.

Submarine Volcanoes

The Kermadec Arc contains numerous underwater volcanoes. Their eruptions may create pumice rafts, hydrothermal
plumes, ash, floating debris and local tsunami hazards.

Geothermal and Hydrothermal Systems

Rotorua, Taupō, Okataina and other volcanic regions contain geysers, hot springs, fumaroles and mud pools.
These features are driven by groundwater heated by hot rock and magma.

Hydrothermal systems can produce sudden steam explosions even without a large magmatic eruption.

Whakaari/White Island: New Zealand’s Most Active Cone Volcano

Whakaari/White Island lies in the Bay of Plenty, approximately 48 kilometres offshore from the
eastern North Island.

The island is only the summit of a much larger submarine stratovolcano. Roughly 70 percent of the volcanic
edifice remains beneath the sea.

Persistent gas emissions, fumaroles, acidic crater lakes, steaming ground and repeated eruptions make Whakaari
New Zealand’s most active cone volcano.

Why the Crater Is Open to the Sea

Part of the older volcanic cone collapsed, allowing the sea to enter the southeastern side of the crater
complex. This breached structure exposes the active crater floor but also reflects a history of instability and
erosion.

Whakaari’s Hydrothermal System

Rainwater and seawater penetrate fractured volcanic rock, where they are heated by magma and hot gas below the
surface.

The heated fluid becomes acidic and chemically alters surrounding rock into clay. This weak material can seal
fractures, trap steam and contribute to explosive pressure buildup.

Fumaroles and Volcanic Gas

Whakaari releases sulfur dioxide, carbon dioxide, hydrogen sulfide, steam and other gases. Emissions may change
with magma movement, pressure and hydrothermal conditions.

Gas can irritate the eyes and lungs, corrode equipment and become dangerous in low or poorly ventilated areas.

Whakaari Eruption History

Whakaari has produced frequent small-to-moderate eruptions during the historical period. Many have been phreatic
or phreatomagmatic, driven by interaction among heat, magma, gas and water.

1914 Crater-Wall Collapse

In September 1914, part of the crater wall collapsed and generated a debris avalanche that killed ten sulfur
miners.

The disaster demonstrated that volcanic danger includes landslides and structural collapse as well as explosive
eruptions.

1975–2000 Eruptive Period

Whakaari experienced a prolonged period of intermittent activity beginning in 1975. Eruptions modified the crater,
produced ash and opened new vents.

This period allowed scientists to observe changing crater lakes, gas emissions and eruptive processes over
several decades.

2012–2016 Activity

Renewed unrest included ash emissions, small eruptions, crater-lake changes and elevated gas output.

These events reinforced the volcano’s ability to shift between hydrothermal unrest and eruptive activity.

The 2019 Whakaari Eruption

On December 9, 2019, Whakaari erupted suddenly while tourists and guides were on the island.

The explosion produced a rapidly expanding cloud of steam, ash, gas and volcanic debris. Pyroclastic surges
swept across parts of the crater floor and toward the coast.

Twenty-two people ultimately died, and many survivors suffered severe burns and respiratory injuries.

Why the Eruption Was So Dangerous

The event was primarily hydrothermal or phreatic. Pressure accumulated beneath altered, partly sealed crater
material until the system failed explosively.

Steam-driven eruptions can be particularly difficult to forecast because:

• The triggering process may occur at shallow depth.
• Warning signals can be subtle or short-lived.
• No large volume of magma must rise immediately before the explosion.
• Hydrothermal seals can fail suddenly.
• Crater visitors have very little time to escape.

Monitoring After 2019

On-island instruments were repeatedly damaged or became difficult to maintain safely. Monitoring increasingly
relied on observation flights, gas measurements, satellites, remote cameras and other off-island techniques.

Whakaari remains a powerful example of why a volcano can be dangerous even when it is not producing a large lava
eruption.

Whakaari Volcanic Hazards

Mount Ruapehu: New Zealand’s Highest Active Volcano

Ruapehu is the largest active volcano in New Zealand and the highest mountain in the North
Island.

It is a broad, complex stratovolcano constructed by repeated lava flows, explosive eruptions and destruction of
earlier summit structures.

Ruapehu has several summit peaks surrounding an active crater containing
Te Wai ā-moe, commonly called Crater Lake.

How Ruapehu Was Built

The volcano has grown over hundreds of thousands of years through eruptions from shifting summit vents.

Lava flows form steep ridges separated by valleys that can channel lahars far down the volcano.

Glaciers and seasonal snow cover the upper slopes. These increase the potential for meltwater floods and lahars
during eruptions.

Ruapehu’s Magma

Ruapehu commonly erupts andesite, a magma more viscous than basalt but generally less silica-rich than rhyolite.

Eruptions may involve explosive fragmentation, lava extrusion and interaction with crater-lake water.

Why Ruapehu Is High Risk

Ruapehu is surrounded by ski areas, roads, railways, hiking routes and river valleys. Even a moderate eruption
can create dangerous lahars with little warning close to the mountain.

Te Wai ā-moe: Ruapehu Crater Lake

Te Wai ā-moe occupies Ruapehu’s active summit crater. Its water is heated by volcanic gas and hydrothermal fluids
rising from below.

The lake’s temperature, chemistry, level and colour can change as heat and gas output vary.

Why the Lake Complicates Eruptions

When magma or hot gas enters the lake, water may flash into steam and intensify an explosion.

Eruptions can eject:

• Water and mud
• Ash and fragmented rock
• Ballistic blocks
• Acidic crater-lake material
• Lahars down multiple valleys

The lake can also be displaced without a major magmatic eruption. Small explosions or crater-wall failure may
release water into drainage channels.

Crater-Lake Heating Cycles

Ruapehu commonly experiences heating and cooling cycles as volcanic gas and fluid flow change beneath the lake.

A warm lake may indicate increased heat input, but temperature alone does not predict an eruption. Scientists
compare lake data with earthquakes, tremor, gas emissions and deformation.

Ruapehu Eruption History

Ruapehu is one of New Zealand’s most frequently active volcanoes. Historical activity has included small crater
explosions, ash eruptions, lava emission and major lahar-producing episodes.

1945 Eruption

Ruapehu produced a prolonged eruption in 1945 that altered the summit crater and deposited ash across parts of
the North Island.

The eruption destroyed the natural outlet from Crater Lake and left a barrier of loose volcanic material and ice.

1953 Tangiwai Disaster

On December 24, 1953, the crater-lake barrier failed and released a lahar down the Whangaehu River.

The flow damaged a railway bridge shortly before an express train arrived. The resulting derailment killed 151
people.

Tangiwai became one of New Zealand’s worst transport disasters and transformed national understanding of volcanic
lahar risk.

1969 and 1975 Eruptions

Explosive activity ejected water, ash and rocks from Crater Lake and generated lahars down the volcano.

1995–1996 Eruptions

A major eruptive sequence produced repeated ash columns, crater explosions and lahars.

Ash disrupted aviation, closed ski areas, affected water supplies and spread across large parts of the central
North Island.

2007 Hydrothermal Eruption

On September 25, 2007, a sudden explosion from Crater Lake ejected rocks and generated lahars.

A climber sheltering near the summit was seriously injured by a large ballistic rock.

The eruption demonstrated that hazardous events can occur abruptly during otherwise relatively quiet periods.

Ruapehu Lahars

Lahars are among Ruapehu’s most important hazards. They consist of water mixed with ash, mud, rocks and volcanic
debris.

How Ruapehu Lahars Form

• Eruptions displacing water from Crater Lake
• Failure of a crater-lake barrier
• Rapid melting of snow and ice
• Heavy rain remobilising volcanic deposits
• Collapse of unstable debris in steep valleys

Lahars commonly follow established drainage systems such as the Whangaehu River. They may travel tens of
kilometres from the crater.

The 2007 Crater-Lake Dam-Break Lahar

After the 1995–1996 eruptions, Crater Lake refilled behind a barrier of loose tephra.

In March 2007, the barrier failed and released a large lahar down the Whangaehu valley.

Monitoring systems, warning procedures and infrastructure modifications helped prevent loss of life.

Learn more:
Lahars Explained: Volcanic Mudflows, Causes and Hazards.

Ngāuruhoe: The Youngest Cone of Tongariro

Ngāuruhoe is the steep, symmetrical cone commonly mistaken for a separate mountain. Geologically,
it is the youngest and most prominent vent of the larger Tongariro volcanic complex.

The cone has grown during approximately the last several thousand years through repeated lava flows and
explosive eruptions.

Ngāuruhoe Eruption Style

Historical activity has included:

• Strombolian explosions
• Vulcanian ash eruptions
• Lava fountains
• Lava flows
• Ballistic blocks
• Small pyroclastic flows

Explosions can eject incandescent material from the summit crater and send ash across Tongariro National Park.

Historic Activity

Ngāuruhoe erupted frequently during the nineteenth and twentieth centuries. Major episodes occurred in 1948–1949,
1954–1955 and 1974–1975.

The 1974–1975 eruptions produced powerful explosions, lava and pyroclastic activity.

No eruption has occurred since 1975, but Ngāuruhoe remains an active vent monitored separately within the
Tongariro system.

Ngāuruhoe and Popular Culture

The cone became internationally recognisable after serving as a visual model and filming location associated with
Mount Doom in The Lord of the Rings.

Its cultural significance to Māori and volcanic danger are more important than its cinematic identity. Summit
climbing has been discouraged because of cultural respect, erosion and safety concerns.

Tongariro Volcanic Complex

Tongariro is not one simple cone. It is a complex volcanic massif composed of more than a dozen
overlapping cones, craters and vents constructed during approximately the last 275,000 years.

Active or geologically young features include:

• Te Māri craters
• Red Crater
• North Crater
• Emerald Lakes
• Blue Lake crater
• Ngāuruhoe

Red Crater

Red Crater is a prominent oxidised vent along the Tongariro Alpine Crossing. Its red, black and brown colours
reflect iron-rich volcanic material altered by heat and gas.

Lava flows and explosive deposits around the crater record relatively young activity.

Emerald Lakes

The Emerald Lakes occupy explosion craters and contain mineral-rich water influenced by volcanic gases and
hydrothermal fluids.

Their colour does not indicate that the water is safe. Crater lakes may be acidic, chemically variable and
surrounded by unstable ground.

Te Māri Craters

The Te Māri vents lie on the northern side of the Tongariro complex. They produced several reported eruptions
during the nineteenth century before reawakening in 2012.

The 2012 Te Māri Eruptions

On August 6, 2012, Tongariro produced a sudden explosion from the Upper Te Māri area after increasing earthquakes
and volcanic unrest.

The eruption opened new vents, produced an ash plume and threw blocks across the surrounding landscape.

Some ejected rocks reached approximately one metre in diameter and landed more than a kilometre from the vent.

Effects of the August Eruption

• Ashfall across parts of the central North Island
• Closure of roads and hiking tracks
• Damage to a Department of Conservation hut
• Ballistic blocks around the Te Māri area
• New steaming vents and crater structures
• Aviation warnings

November 2012 Eruption

A second eruption occurred on November 21, 2012. It produced an ash cloud but was smaller and shorter-lived than
many observers had feared.

The events showed that a volcanic complex can reactivate after more than a century without a confirmed eruption.

Lessons from Tongariro

The 2012 activity reinforced several important points:

• Long repose does not mean extinction.
• Hydrothermal explosions may produce limited warning.
• Ballistic rocks can travel beyond the immediate crater.
• Popular hiking routes can cross active volcanic terrain.
• Trail closures are a life-safety measure rather than an inconvenience.

How Whakaari, Ruapehu and Tongariro Are Monitored

New Zealand’s volcanoes are monitored through GeoNet, a national geohazard-monitoring system
operated with scientific expertise from Earth Sciences New Zealand/GNS Science.

No single instrument can predict an eruption. Scientists look for combinations of changes across several
monitoring networks.

Seismic Monitoring

Seismometers detect rock-fracturing earthquakes, volcanic tremor, explosions, lahars and movement of fluids.

Crater-Lake Monitoring

At Ruapehu, scientists measure Te Wai ā-moe temperature, water chemistry and lake level.

Gas Measurements

Observation flights and ground instruments measure sulfur dioxide, carbon dioxide and other gases.

Ground Deformation

GNSS stations, tiltmeters and satellite radar can detect inflation, subsidence and movement caused by pressure
changes underground.

Visual and Thermal Cameras

Cameras record steam plumes, crater changes, ash emissions and thermal anomalies.

Satellite Monitoring

Satellites are especially important at offshore Whakaari and remote Kermadec volcanoes. They can detect heat,
sulfur dioxide and ash clouds.

Lahar Detection

Sensors around Ruapehu can detect ground vibration and changing river conditions associated with lahars.

Māori Connections to New Zealand’s Volcanoes

New Zealand’s volcanoes are ancestral mountains, sacred landscapes and living presences within Māori history and
identity. Their Māori names and narratives should not be treated as decorative additions to geological
descriptions.

Ruapehu, Tongariro and Ngāuruhoe hold profound significance for Ngāti Tūwharetoa and other iwi of the central
North Island.

Tongariro National Park became the first national park in New Zealand after the central mountain peaks were
gifted to the Crown in 1887 by Horonuku Te Heuheu Tūkino IV with the intention of protecting their sacred status.

Ngāuruhoe and Summit Respect

Climbing to the summit of Ngāuruhoe or entering sacred crater areas may conflict with tikanga and requests from
mana whenua.

Respecting cultural guidance also reduces erosion and exposure to sudden volcanic hazards.

Whakaari

The name Whakaari is connected to Māori voyaging and oral history. The volcano is a significant ancestral
landmark in the Bay of Plenty and should be referred to by its Māori name alongside or instead of the colonial
name White Island.

Scientific and Indigenous Knowledge

Oral histories, place names and whakapapa preserve observations of landscape change, eruptions and relationships
between people and volcanic environments.

Modern hazard understanding is strengthened when scientific monitoring and mātauranga Māori are approached with
respect rather than treated as competing systems.

Volcano Tourism and Safety

New Zealand’s volcanic landscapes attract hikers, skiers, climbers, photographers and geothermal tourists.
Accessibility can create the false impression that the terrain is permanently safe.

Tongariro Alpine Crossing

The Tongariro Alpine Crossing passes close to active vents, crater lakes and steep volcanic slopes.

Hazards include:

• Sudden eruptions
• Ballistic rocks
• Volcanic gas
• Snow and ice
• Extreme wind
• Poor visibility
• Rockfall
• Rapid weather change

Ruapehu Ski Areas

Ski fields occupy Ruapehu’s slopes below an active crater lake. Warning systems and lahar procedures reduce risk
but cannot remove it completely.

Whakaari

The 2019 disaster demonstrated the exceptional danger of standing inside the crater of an active hydrothermal
volcano.

Essential Safety Rules

• Check GeoNet and Department of Conservation information before departure.
• Respect track closures and exclusion zones.
• Do not enter active crater areas to obtain photographs.
• Prepare for alpine weather throughout the year.
• Know the nearest high ground and lahar escape route.
• Do not rely on the absence of visible ash or lava as proof of safety.
• Follow guidance from mana whenua and authorised land managers.

Taupō Volcano: New Zealand’s Enormous Active Caldera

Beneath the waters and surrounding landscape of Lake Taupō lies one of the world’s most
powerful and frequently active rhyolitic volcanic systems.

Taupō is not a conventional cone-shaped volcano. It is a broad caldera complex containing submerged vents,
faults, geothermal areas, lava domes and deposits from repeated explosive eruptions.

The modern lake occupies only part of the larger volcanic depression. Its shoreline does not precisely define
the boundaries of the magma system or the full area affected by previous caldera collapse.

How the Taupō Caldera Formed

Caldera collapse occurs when an eruption removes a large volume of magma from underground and the overlying crust
can no longer support itself.

At Taupō, repeated explosive eruptions and episodes of collapse created overlapping structural depressions.
Faulting, subsidence and later sedimentation helped shape the lake basin visible today.

The caldera has not remained static. Later eruptions opened new vents, extruded lava domes and further modified
the basin.

Taupō’s Rhyolitic Magma

Taupō primarily erupts rhyolite, a silica-rich magma that is significantly more viscous than basalt.

Rhyolitic magma can trap water vapour, carbon dioxide and other gases. As magma rises and pressure falls, gas
expands. If it cannot escape gradually, the magma may fragment explosively into ash and pumice.

Rhyolitic eruptions may produce:

• High Plinian eruption columns
• Widespread pumice and ashfall
• Pyroclastic density currents
• Ignimbrite sheets
• Caldera collapse
• Lava domes and short viscous flows
• Earthquakes and large-scale ground deformation

Taupō Eruption History

Taupō has erupted many times during approximately the last 300,000 years. Its known activity includes several
exceptionally large eruptions and numerous smaller events.

The size difference among Taupō eruptions is enormous. A future eruption should not automatically be assumed to
resemble the largest event in the geological record.

Early Taupō Volcanism

Volcanic activity in the Taupō region began before the present caldera and lake formed. Older rhyolitic eruptions
produced lava, pumice and pyroclastic deposits that are partly buried beneath younger material.

Repeated eruptions gradually developed a long-lived silicic magma system within the extending crust of the central
Taupō Volcanic Zone.

The Whakamaru-Group Ignimbrites

Before the modern Taupō system became dominant, extremely large eruptions occurred from the broader central
volcanic zone. The Whakamaru-group ignimbrites cover extensive parts of the North Island.

These deposits demonstrate that the region has supported huge crustal magma systems for hundreds of thousands of
years.

Post-Oruanui Activity

Taupō did not become inactive after the Oruanui supereruption. Numerous smaller eruptions followed, including
pumice-producing explosions, lava-dome extrusion and the extraordinarily violent Taupō eruption approximately
1,800 years ago.

The Oruanui Supereruption

The Oruanui eruption occurred approximately 25,500 years ago and was the largest known eruption
on Earth during roughly the last 70,000 years.

It is classified as a magnitude-eight or supereruption because it released an enormous volume of rhyolitic magma,
ash, pumice and pyroclastic material.

A Complex Multi-Phase Eruption

Oruanui was not one single instantaneous explosion. Geological deposits indicate a complex sequence involving
repeated eruptions, pauses, water interaction and changing vent conditions.

Activity included:

• Powerful eruption columns
• Widespread pumice and ashfall
• Repeated column collapse
• Pyroclastic density currents
• Interaction with a pre-existing lake and groundwater
• Large-scale caldera collapse

Effects Across the North Island

Ash spread across much of New Zealand and into the surrounding ocean. Thick pyroclastic-flow deposits transformed
the central North Island.

Rivers were blocked or redirected, valleys were filled and the landscape was buried beneath pumice and ignimbrite.
The eruption played a major role in shaping the basin later occupied by Lake Taupō.

Was Oruanui a Global Extinction Event?

No. Oruanui was an enormous eruption with major regional environmental effects, but it did not cause a global
mass extinction.

Its climatic influence remains a subject of research because the total effect depends on sulfur release, plume
height, eruption duration, atmospheric circulation and the climate conditions at the time.

The Taupō or Hatepe Eruption

Approximately 1,800 years ago, Taupō produced the most violent eruption known anywhere on Earth during the last
5,000 years.

The event is variously called the Taupō eruption, Hatepe eruption or
Horomatangi eruption.

It was far smaller than Oruanui in total volume but released part of its magma with extraordinary speed and
intensity.

Early Eruption Phases

The eruption began with several pumice and ash falls. Winds distributed tephra eastward across the central North
Island and toward Hawke’s Bay.

Interaction between magma and lake water influenced some stages, producing highly fragmented ash and explosive
surges.

The Final Pyroclastic Density Current

The eruption culminated in an extremely mobile pyroclastic density current that spread outward from the caldera
across a vast area.

The hot current climbed over high terrain, devastated forests and deposited ignimbrite across the central North
Island.

Its mobility demonstrates that pyroclastic currents from very large eruptions do not simply remain in valleys.
They can overtop ridges and spread across complex landscapes.

Was the Taupō Eruption Witnessed by Māori?

Current archaeological and chronological evidence places the eruption centuries before permanent Polynesian
settlement of New Zealand.

Claims connecting the eruption directly with Māori eyewitness accounts should therefore be treated cautiously
unless supported by reliable dating and cultural scholarship.

Volcanic Unrest at Taupō

Taupō experiences periods of earthquake swarms, ground deformation and changing geothermal activity.

These episodes reflect movement of magma, gas, hot fluids or stress along faults within the active caldera.

What Does Taupō Unrest Look Like?

• Earthquake swarms beneath or around the lake
• Uplift or subsidence measured by GNSS and satellites
• Changes in hot springs and geothermal systems
• Fault movement and occasional felt earthquakes
• Changes in volcanic gas or lake chemistry

Most unrest episodes do not end in eruption. Magma may remain deep underground, pressure may decline or
hydrothermal fluids may adjust without magma reaching the surface.

However, unrest can still create hazards through earthquakes, landslides, hydrothermal explosions and changing
ground levels.

Taupō Volcanic Hazards

Okataina Volcanic Centre

The Okataina Volcanic Centre lies east of Rotorua and includes the Tarawera volcanic complex,
Haroharo caldera, multiple rhyolitic lava domes and large eruption deposits.

Okataina is one of New Zealand’s most active and productive rhyolitic volcanic systems.

Unlike a single central cone, Okataina contains vents spread across a broad area. Future activity could open from
different parts of the volcanic centre.

Okataina’s Eruption Styles

Okataina has produced:

• Rhyolitic pumice eruptions
• Lava domes and coulees
• Pyroclastic density currents
• Widespread ashfall
• Basaltic fissure eruptions
• Phreatomagmatic explosions

This range is unusual. The volcanic centre is dominated by rhyolite, but the 1886 Tarawera eruption involved
basaltic magma rising through the existing silicic system.

Haroharo Volcanic Complex

Haroharo forms a long rhyolitic dome complex within the northern part of Okataina.

Its lava domes and flows were constructed during multiple episodes rather than one continuous eruption.

Rhyolitic domes can grow slowly but become dangerous if steep fronts collapse and produce pyroclastic flows.

The Kaharoa Eruption

The Kaharoa eruption occurred during the early fourteenth century and was the largest rhyolitic
eruption in New Zealand during the last millennium.

It produced widespread ash and several large rhyolitic lava domes along the Tarawera complex.

Kaharoa Tephra

Ash from the eruption spread across parts of the North Island and now forms an important dating layer for
archaeology, soil science and environmental studies.

Because the eruption occurred near the time of early Māori settlement, the Kaharoa ash layer helps researchers
date sites and landscape changes.

Tarawera Domes

Viscous rhyolitic lava accumulated above the vents and formed steep domes along the summit area.

These older domes later became the landscape fractured by the 1886 basaltic eruption.

Mount Tarawera

Mount Tarawera is a long volcanic complex formed by overlapping rhyolitic lava domes southeast
of Rotorua.

Its summit is split by a deep fissure system created during the catastrophic eruption of June 10, 1886.

Before 1886, Tarawera was already a young active volcanic complex, but its known recent eruptions had primarily
involved silica-rich magma.

Why the 1886 Eruption Was Unusual

The 1886 event involved basaltic magma, which rose rapidly through the older rhyolitic dome complex.

The magma opened a fissure extending across Tarawera and through the nearby Rotomahana hydrothermal area.

This interaction among basaltic magma, groundwater, lakes and hydrothermal systems created several contrasting
eruption styles during the same night.

The 1886 Mount Tarawera Eruption

Shortly after midnight on June 10, 1886, earthquakes and explosions marked the beginning of one of New Zealand’s
deadliest historical eruptions.

A line of vents opened along Mount Tarawera. Lava fountains and explosive activity illuminated the sky while ash,
scoria and volcanic bombs fell across the surrounding region.

Fissure Propagation

The eruptive fissure extended for approximately 17 kilometres from the Tarawera dome complex through the
Rotomahana area and into the Waimangu region.

Along Tarawera, the eruption was largely basaltic and involved powerful fountains, explosions and scoria
production.

Rotomahana Explosions

At Rotomahana, magma encountered lake water and a vigorous hydrothermal system.

Violent phreatomagmatic explosions excavated craters and produced base surges—fast, ground-hugging clouds of ash,
steam and debris.

Destruction of Communities

Villages around Lake Tarawera and Rotomahana were buried or destroyed. Te Wairoa became the best-known settlement
affected by the disaster.

More than one hundred people died, with Māori communities suffering most of the fatalities and destruction.

The Pink and White Terraces

Before the eruption, the Pink and White Terraces at Lake Rotomahana were internationally famous silica formations
created by geothermal water.

The eruption transformed the lake basin and buried, destroyed or submerged the terraces. Their exact surviving
remains and locations continue to attract scientific and historical interest.

Landscape Transformation

Rotomahana expanded dramatically after the eruption as water filled the new craters and altered basin.

New geothermal systems developed along the fissure, including the Waimangu hydrothermal area.

Tarawera and Okataina Hazards

Rotorua Caldera

The city of Rotorua and Lake Rotorua lie within a large volcanic caldera formed by an explosive eruption hundreds
of thousands of years ago.

Although Rotorua has not produced a known recent magmatic eruption, it remains a monitored volcanic and
geothermal system.

Mamaku Ignimbrite

The caldera-forming eruption released rhyolitic pumice and pyroclastic flows that deposited the Mamaku Ignimbrite
across a broad area.

Collapse of the ground above the emptied magma reservoir created the structural basin later occupied by Lake
Rotorua.

Ngongotahā and Later Activity

Rhyolitic lava formed features such as Mount Ngongotahā after or during stages of caldera development.

The modern geothermal systems around Rotorua are powered by heat remaining within the broader Taupō Volcanic
Zone.

Rotorua Volcanic Hazards

Immediate hazards are more likely to involve geothermal gas, boiling water, unstable ground and hydrothermal
explosions than a sudden giant caldera eruption.

Long-term volcanic hazard remains because Rotorua belongs to a young regional magmatic system and has active
faults beneath and around the city.

Rotorua Geothermal Fields

Rotorua is internationally known for geysers, steaming ground, mud pools, hot springs and sulfur-rich fumaroles.

Major geothermal areas include:

• Whakarewarewa
• Te Puia
• Ōhinemutu
• Kuirau Park
• Waiotapu
• Waimangu
• Hell’s Gate/Tikitere

How Rotorua’s Geothermal Systems Work

Rainwater penetrates faults and porous volcanic rock. At depth, it is heated by hot rock and magmatic gases.

The heated water rises again through fractures. Pressure, temperature and underground plumbing determine whether
it emerges as a hot spring, geyser, steaming vent or mud pool.

Hydrothermal Alteration

Hot acidic fluids change volcanic rock into clay and other weak minerals.

Altered ground may collapse unexpectedly, creating dangerous holes beneath apparently solid surfaces.

Carbon Dioxide and Hydrogen Sulfide

Geothermal areas release carbon dioxide and hydrogen sulfide. Gas may accumulate in enclosed or low-lying spaces.

Hydrogen sulfide has a characteristic rotten-egg smell at low concentrations, but smell cannot be relied upon as
a safety warning.

New Zealand Geysers and Hot Springs

A geyser requires heat, abundant groundwater and a plumbing system capable of trapping pressurised water.

Water deep underground can become hotter than its normal boiling point because of pressure. When part of the
water begins to boil, pressure decreases and the remaining superheated water rapidly flashes into steam.

Pōhutu Geyser

Pōhutu at Whakarewarewa is New Zealand’s largest active geyser and one of Rotorua’s most recognisable geothermal
features.

Its eruptions reflect the repeated filling, heating and depressurisation of an underground fracture system.

Human Effects on Geysers

Extraction of geothermal water can lower underground pressure and reduce geyser activity.

Regulation of geothermal wells around Rotorua helped restore or protect activity at some surface features.

Explore the science:

Geysers and Hydrothermal Features Explained
.

Waimangu Volcanic Rift Valley

The Waimangu Volcanic Rift Valley developed after the 1886 Tarawera eruption opened craters
southwest of Lake Rotomahana.

It is one of the world’s youngest major geothermal systems and provides a rare example of a hydrothermal
landscape whose birth was documented historically.

Waimangu Geyser

Between 1900 and 1904, Waimangu Geyser produced enormous eruptions of dark water, mud and rock.

Some jets reportedly reached several hundred metres in height, making it the largest known geyser active during
the historical period.

Its activity ended after changes to the underground water system.

Frying Pan Lake

Frying Pan Lake occupies an explosion crater and is one of the world’s largest hot springs.

Steam, bubbling water and geothermal gases reveal continuing heat flow beneath the valley.

Inferno Crater

Inferno Crater contains a vivid blue acidic lake whose level and temperature change through a natural cycle linked
to the underground hydrothermal system.

Hydrothermal Explosion Hazard

Waimangu remains capable of sudden steam-driven activity. Visitors must remain on approved tracks because thin
crust, boiling water and unstable altered ground can cause severe injury.

Reporoa, Kapenga, Ōhakuri, Mangakino and Whakamaru Calderas

The central Taupō Volcanic Zone contains several older caldera systems that are less visually obvious than Lake
Taupō or Rotorua.

Their outlines may be partly buried by younger lava, sediment and ignimbrite, but their eruptions played a major
role in constructing the central North Island.

Reporoa Caldera

Reporoa is a broad volcanic depression associated with rhyolitic eruptions and active geothermal systems.

The area has also experienced hydrothermal explosions, including events capable of excavating craters and
throwing mud and debris.

Kapenga Caldera

Kapenga lies between Rotorua and Reporoa and is partly obscured by younger volcanic deposits and faulting.

It forms part of the complicated cluster of central-zone calderas rather than a single isolated volcano.

Ōhakuri Caldera

Ōhakuri produced major rhyolitic eruptions and is now partly occupied by the Waikato River and hydroelectric
reservoir.

Mangakino and Whakamaru

Mangakino and Whakamaru were sources of large prehistoric eruptions that spread ignimbrites over extensive parts
of the North Island.

Their modern eruption probability is considered lower than that of Taupō or Okataina, but their deposits reveal
the extraordinary long-term output of the Taupō Volcanic Zone.

Auckland Volcanic Field: A City Built Across Dozens of Volcanoes

The Auckland Volcanic Field contains approximately 53 recognised volcanic centres spread across
Tāmaki Makaurau Auckland.

Activity began hundreds of thousands of years ago and continued until the Rangitoto eruptions approximately six
centuries ago.

The field is still considered active even though no eruption has occurred during European settlement.

Why Magma Rises Beneath Auckland

Auckland volcanism is not located on the main Taupō volcanic front. Basaltic magma rises from the mantle through
weaknesses in the crust beneath the wider Auckland region.

The precise cause of the field remains scientifically investigated, but it reflects small-volume intraplate or
back-arc-related mantle melting rather than a large central magma chamber beneath the city.

Monogenetic Does Not Mean Simple

An individual Auckland eruption may last weeks, months or years and can shift among several nearby vents.

Magma interacting with groundwater or harbour water may produce violent explosions before activity becomes more
lava-dominated.

Major Volcanoes of the Auckland Volcanic Field

Rangitoto: Auckland’s Youngest Volcano

Rangitoto erupted approximately 600 years ago and was witnessed by Māori communities living
around the Hauraki Gulf.

It is much larger than the other Auckland centres and produced a volume of lava comparable to the combined output
of the rest of the field.

Rangitoto’s Eruption Sequence

Initial activity occurred through shallow seawater, generating explosive phreatomagmatic eruptions.

As lava and fragmented material built land above the sea, activity became less water-dominated and extensive
basaltic lava flows constructed the island.

Later Strombolian eruptions built the prominent summit scoria cones.

Did Rangitoto Erupt More Than Once?

Geological dating indicates that Rangitoto’s activity was more prolonged and complex than a single brief
explosion.

Separate eruptive phases may have occurred within a broader episode lasting years or decades, but Rangitoto is
still treated as one volcanic centre rather than a repeatedly reactivated central volcano.

Māori History

Rangitoto is known as Te Rangi-i-totongia-a-Tama-te-kapua in traditions connected with the ancestral landscape of
Tāmaki Makaurau.

Footprints preserved between volcanic deposits on Motutapu provide direct archaeological evidence of people
living beside the eruption.

What Would a Future Auckland Eruption Look Like?

The exact vent location cannot be predicted before clear unrest develops.

A future crisis might begin with:

• Deep earthquake swarms
• Earthquakes migrating toward the surface
• Ground uplift or cracking
• Changes in groundwater chemistry
• Gas emissions
• Increasing volcanic tremor

Scenario 1: Eruption on Land

Magma rising beneath a suburb could generate earthquakes and ground fractures before opening a new vent.

Early explosions might produce ash and ballistic blocks, followed by construction of a scoria cone and lava
flows.

Scenario 2: Eruption in a Harbour or Wetland

Magma-water interaction could generate violent explosions, base surges and a broad tuff ring.

Harbour closures, waves, floating debris and damage to port infrastructure could accompany the eruption.

Scenario 3: Multiple Vents

A fissure might open several vents across a neighbourhood or industrial corridor.

Even before lava arrives, evacuation zones, ashfall and infrastructure shutdown could displace large parts of the
city.

Economic and Infrastructure Effects

Potential consequences include:

• Closure of Auckland Airport
• Disruption of ports and shipping
• Damage to motorways and railway lines
• Loss of electricity, water and communications
• Evacuation of hospitals, schools and suburbs
• Long-term housing displacement
• Severe national economic disruption

The event would probably be small compared with a Taupō caldera eruption but could become New Zealand’s most
expensive natural disaster because of its urban location.

Tūhua/Mayor Island

Tūhua/Mayor Island lies offshore in the Bay of Plenty and is the exposed summit of a large
rhyolitic caldera volcano.

The island contains lava domes, obsidian flows, explosion craters and two prominent caldera lakes.

Tūhua Obsidian

Tūhua is famous for high-quality black obsidian, a natural volcanic glass formed when silica-rich lava cools
rapidly.

Māori transported Tūhua obsidian across Aotearoa for use in cutting tools and other purposes. Its distribution at
archaeological sites records trade and voyaging networks.

Caldera and Lava Domes

Large explosive eruptions created the island’s caldera, while later rhyolitic lava formed domes and obsidian
flows.

Tūhua has not erupted during recorded history but retains a geologically young volcanic system.

Potential Hazards

• Explosive rhyolitic eruption
• Pumice and ashfall
• Pyroclastic density currents
• Lava-dome collapse
• Submarine or coastal explosions
• Local tsunami or hazardous waves

Kermadec Islands and Submarine Volcanoes

The Kermadec Arc extends approximately 1,220 kilometres northeastward from New Zealand.

It contains islands, seamounts, stratovolcanoes and large calderas. Most remain completely below sea level.

Around 80 submarine volcanoes occur along the wider Tonga–Kermadec Arc, and many host active hydrothermal systems.

Why the Kermadec Arc Is Important

The arc provides a natural laboratory for studying:

• Subduction-zone magma generation
• Submarine explosive eruptions
• Caldera formation beneath the sea
• Hydrothermal vents and mineral deposits
• Deep-sea ecosystems
• The transition from volcanic arc to back-arc basin

Raoul Island

Raoul is the largest island in the Kermadec group and the summit of a large caldera volcano.

It contains Blue Lake, Green Lake and active hydrothermal areas. Historical eruptions have included steam-driven
explosions and small magmatic events.

Macauley Island

Macauley is the exposed rim of a large submarine caldera. Cliffs reveal thick volcanic deposits created by
powerful past eruptions.

Much of the volcanic system remains beneath the sea.

Curtis and Cheeseman Islands

These small islands form the exposed parts of a volcanic complex with fumarolic and hydrothermal activity.

Changes in shoreline, gas output and water temperature may reflect continuing heat beneath the system.

Havre Submarine Volcano

Havre is a large submarine caldera volcano in the Kermadec Arc.

In July 2012, satellites and ships detected an enormous pumice raft spreading across the southwest Pacific.

Later oceanographic surveys identified Havre as the eruption source.

The 2012 Havre Eruption

The eruption produced:

• A vast floating pumice raft
• Submarine lava flows and domes
• Ash and fragmented volcanic glass
• Deposits across the caldera floor
• Hydrothermal changes

The event was one of the largest silicic submarine eruptions directly investigated with modern instruments.

Why Pumice Floats

Pumice contains abundant gas-filled pores. Fresh fragments may remain buoyant for months or years until water
enters the pore spaces.

Rafts may travel thousands of kilometres, carry marine organisms and affect ships, fishing equipment and coastal
facilities.

Brothers Volcano

Brothers is a large submarine caldera volcano in the southern Kermadec Arc.

It contains one of the most intensively studied hydrothermal systems in the southwest Pacific.

Black Smokers

Seawater circulates through hot volcanic crust, reacts with rock and rises through vents carrying dissolved
metals and minerals.

When the hot fluid mixes with cold seawater, minerals precipitate and form dark plumes known as black smokers.

Mineral Deposits

Hydrothermal activity deposits copper, zinc, gold and other metals around vents and beneath the seafloor.

These systems are scientifically valuable because they show how volcanism, seawater and mineral formation
interact.

Deep-Sea Life

Vent ecosystems rely on chemosynthesis rather than sunlight. Microorganisms use sulfur and other chemicals to
produce energy, supporting specialised animal communities.

Other Important Kermadec Volcanoes

Hazards from New Zealand’s Submarine Volcanoes

Learn more:

Submarine Volcanoes and Seamounts Explained
.

Geothermal Energy in New Zealand

The Taupō Volcanic Zone contains some of the world’s most productive high-temperature geothermal systems.

Hot rock heats groundwater at depth. Wells bring steam and hot fluid to the surface, where their energy can
generate electricity or provide direct heating.

Major Geothermal Fields

• Wairakei
• Kawerau
• Ōhaaki
• Rotokawa
• Ngā Awa Pūrua
• Mokai
• Te Mihi

Wairakei

Wairakei near Taupō became one of the world’s earliest large geothermal electricity developments.

Steam and hot water from deep reservoirs are used to drive turbines before some fluid is reinjected underground.

Benefits

• Reliable electricity generation
• Low dependence on weather
• Lower operational carbon emissions than fossil fuels
• Direct industrial and heating uses
• Domestic energy supply

Environmental and Geological Issues

• Subsidence caused by reservoir pressure decline
• Changes to geysers and hot springs
• Release of carbon dioxide and hydrogen sulfide
• Mineral-rich wastewater
• Induced microearthquakes
• Cultural effects on geothermal taonga

Modern geothermal management increasingly uses reinjection, reservoir modelling and consultation with mana whenua
to reduce impacts.

Major Volcanic Hazards in New Zealand

New Zealand’s volcanic hazards vary dramatically because the country contains cone volcanoes, calderas,
monogenetic fields, crater lakes and submarine systems.

Volcanic Ashfall Hazards

Volcanic ash is fragmented rock, minerals and glass smaller than two millimetres. It is abrasive, dense and
potentially harmful.

Effects on Health

Fine ash may irritate the eyes and respiratory system. People with asthma or other lung conditions may be
especially vulnerable.

Effects on Agriculture

Ash can bury pasture, contaminate water troughs, damage crops and interfere with livestock feeding.

Fluorine and other chemicals attached to ash particles may create additional livestock hazards during some
eruptions.

Effects on Infrastructure

• Roof loading and collapse
• Blocked gutters and drains
• Power-line flashover
• Damage to engines and machinery
• Reduced road visibility and traction
• Contaminated water-treatment systems
• Communication failures

Wet Ash

Rain-soaked ash is much heavier than dry ash and can create dangerous loads on roofs.

It also forms slippery mud and may be remobilised into drains, rivers and sediment flows.

Volcanic Ash and Aviation

New Zealand’s domestic and international flight paths cross or pass near active volcanic regions.

Ash clouds from Ruapehu, Tongariro, Whakaari, Taupō, Okataina or the Kermadec Arc could disrupt aviation.

Why Ash Is Dangerous to Aircraft

• Particles can melt inside jet engines.
• Engines may lose power or shut down.
• Ash can abrade cockpit windows.
• Air filters and sensors may become blocked.
• Static electricity can disrupt communications.

Volcanic Ash Advisory Centres, meteorological agencies, GeoNet and aviation authorities use observations,
forecasts and satellite data to track hazardous clouds.

The 1995–1996 Ruapehu eruptions caused extensive aviation disruption and demonstrated that even moderate New
Zealand eruptions can affect flights across the country.

Volcanic Landslides and Debris Avalanches

Volcanoes are built from fractured lava, ash, loose debris and rock weakened by acidic hydrothermal fluids.

Their steep slopes may collapse because of:

• Earthquakes
• Magma intrusion
• Hydrothermal alteration
• Heavy rainfall
• Glacial erosion
• Over-steepening during dome growth

Taranaki and Cone Collapse

Although covered in greater detail in Part 3, Taranaki’s landscape contains enormous debris-avalanche deposits
from repeated prehistoric collapses.

Whakaari Crater-Wall Collapse

The 1914 disaster showed that hydrothermally altered crater walls can fail without a major magmatic eruption.

Caldera-Lake Landslides

Landslides entering Lake Taupō, Lake Tarawera or other volcanic lakes could generate local waves and shoreline
flooding.

Volcanic Tsunami Hazards

New Zealand’s volcanic lakes, offshore cones and submarine calderas create several possible volcanic tsunami
mechanisms.

Potential Sources

• Submarine eruptions
• Volcanic-island flank collapse
• Pyroclastic density currents entering water
• Underwater caldera collapse
• Landslides into crater lakes
• Rapid displacement during phreatomagmatic explosions

Local Warning Time

Waves generated close to shore may arrive within minutes. Strong shaking, an explosion, sudden water withdrawal
or an unusual roar should prompt movement away from the coast or lake edge.

Learn more:
Volcanic Tsunamis Explained.

How Taupō, Okataina, Auckland and Offshore Volcanoes Are Monitored

GeoNet combines several monitoring techniques because no single signal can reliably determine whether an eruption
will occur.

Earthquake Monitoring

Seismometers detect rock fracture, fluid movement, volcanic tremor and fault earthquakes.

The depth and migration of earthquakes may reveal magma moving toward the surface.

Ground Deformation

GNSS receivers, lake-level measurements, tiltmeters and satellite radar identify uplift, subsidence and fault
movement.

These methods are especially important at broad calderas where deformation may extend across tens of kilometres.

Geochemistry

Scientists sample hot springs, lakes, soil gases and fumaroles to detect changes in temperature, acidity, gas
ratios and isotopic composition.

Visual and Thermal Observations

Cameras, aircraft, drones and satellites document steam, heat anomalies, crater changes and ash plumes.

Marine Surveys

Submarine volcanoes require sonar mapping, water-column instruments, remotely operated vehicles and autonomous
underwater vehicles.

Probabilistic Forecasting

Scientists combine current observations with each volcano’s geological history to estimate possible outcomes.

Forecasts may assess whether unrest is more likely to decline, continue or progress toward eruption, but they
cannot remove uncertainty.

Explore Related Volcano Guides

Taranaki Maunga: New Zealand’s Western Stratovolcano

Taranaki Maunga, also historically called Mount Taranaki or Mount Egmont, rises above the western
North Island as one of New Zealand’s most symmetrical and visually recognisable volcanoes.

Unlike Ruapehu, Tongariro and Ngāuruhoe, Taranaki lies west of the main Taupō Volcanic Zone. It belongs to a
separate volcanic province associated with changes in the geometry of subduction, crustal structure and magma
pathways beneath the western North Island.

Taranaki is a large andesitic stratovolcano built through repeated lava flows, explosive eruptions, dome growth,
pyroclastic activity and collapse of earlier volcanic structures.

How Taranaki Was Built

The present cone is only the latest major volcano in a westward-migrating sequence of volcanic centres.
Older eroded remnants lie to the northwest and include Kaitake and Pouākai.

These older centres record the movement of volcanic activity through the region over hundreds of thousands of
years.

Taranaki’s modern cone has been repeatedly rebuilt after explosive eruptions and major collapses. Lava flows form
steep ridges, while rivers and glaciers have cut valleys into the upper slopes.

Summit Crater and Fanthams Peak

The summit contains a small crater that is commonly filled with snow or ice. South of the main cone lies
Fanthams Peak, also known as Panitahi, a prominent subsidiary vent.

Future activity could occur from the summit, from flank vents or through newly opened fractures.

Taranaki’s Magma

Taranaki primarily erupts andesite and related intermediate-composition magma. This magma may produce both lava
flows and explosive activity.

Viscous magma can accumulate as lava domes or plugs. If these structures collapse, they may generate pyroclastic
density currents and hot avalanches.

Taranaki Eruption History

Geological studies show that Taranaki has erupted many times during the Holocene. Its activity has included
explosive eruptions, lava flows, dome growth, widespread ashfall and repeated collapse of parts of the cone.

Burrell Lapilli Eruption

One of Taranaki’s major prehistoric explosive events deposited pumice and lapilli across the surrounding region.
Deposits such as these help volcanologists reconstruct eruption frequency, wind direction and eruption magnitude.

Recent Pre-European Activity

Some of Taranaki’s youngest deposits are only several centuries old. Māori oral traditions and geological
evidence preserve knowledge of a landscape that remained volcanically active relatively recently.

The exact date and interpretation of the most recent activity vary among studies because small summit or dome
events may leave limited deposits.

Long Repose Intervals

Taranaki may remain quiet for centuries between eruptive episodes. Long repose can allow vegetation, settlements
and infrastructure to spread across areas affected by older eruptions.

This creates a risk problem: communities may have no direct cultural memory of a major event even though the
volcano remains geologically active.

Taranaki Flank Collapse and Debris Avalanches

Taranaki has experienced repeated large-scale collapse. Sections of the volcanic cone failed and spread enormous
masses of rock across the surrounding landscape.

These deposits are known as debris-avalanche deposits. They contain chaotic blocks of the former
volcano and may extend many kilometres from the present cone.

Why Stratovolcanoes Collapse

• Steep slopes become gravitationally unstable.
• Hydrothermal fluids weaken rock into soft clay.
• Magma intrusions push the edifice outward.
• Earthquakes fracture the cone.
• Heavy rain and erosion remove support.
• Lava domes overload or destabilise upper slopes.

A future collapse would not necessarily require a very large eruption. Structural failure could occur during
magma intrusion, earthquake activity or renewed dome growth.

Landscape of Hummocks

Small hills and irregular terrain around Taranaki preserve remnants of ancient debris avalanches. Similar
hummocky landscapes occur around Mount St. Helens and other collapsed stratovolcanoes.

Taranaki Volcanic Hazards

Why a Taranaki Eruption Would Be a Major National Emergency

Taranaki is surrounded by productive farmland, towns, roads, electricity networks, pipelines and energy
infrastructure.

The region’s dairy industry and transport links could be severely affected by ashfall, evacuation and water
contamination even outside the most dangerous areas close to the volcano.

Communities Potentially Affected

The exact hazard would depend on the vent, eruption style and wind direction, but communities that could face
disruption include:

• New Plymouth
• Stratford
• Inglewood
• Ōpunake
• Hāwera
• Numerous rural settlements and farms

Energy and Transport Infrastructure

Roads around the mountain could be cut by lahars or ash. Electricity transmission, communications and natural-gas
infrastructure might also be disrupted.

A long eruption could create repeated evacuation zones and economic impacts lasting months or years.

Northland Volcanic Fields

Te Tai Tokerau/Northland contains several volcanic fields and older volcanic complexes extending from Whangārei
toward Kaikohe, the Bay of Islands and the Far North.

Most Northland volcanoes are much smaller than Ruapehu or Taranaki. They include basaltic cones, lava flows,
explosion craters and deeply eroded remnants of older volcanic centres.

Kaikohe–Bay of Islands Volcanic Field

The Kaikohe–Bay of Islands field contains numerous basaltic vents, cones and lava flows.

Lake Ōmāpere occupies part of a landscape influenced by lava flows that altered drainage and blocked valleys.

The field is considered potentially active because some eruptions occurred during the late Quaternary or
geologically recent past.

Whangārei Volcanic Field

The Whangārei region contains eroded basaltic cones, volcanic necks and lava flows.

Many original volcanic forms have been heavily modified by erosion, quarrying, vegetation and urban development.

Older Northland Volcanic Complexes

Northland also preserves older andesitic and basaltic volcanic systems whose roots are exposed as resistant plugs,
dikes and intrusive rocks.

These ancient centres are not equivalent to the monitored active systems of the Taupō Volcanic Zone, but they
record an extended and complicated history of magmatism in northern New Zealand.

Could Northland Erupt Again?

Northland is monitored as a potentially active volcanic region, although its near-term eruption probability is
considered low compared with frequently restless systems such as Whakaari or Ruapehu.

Like Auckland, parts of Northland contain monogenetic volcanic fields. A future eruption would probably open a new
vent rather than reactivate the exact summit of a familiar cone.

Possible Warning Signs

• Deep earthquake swarms
• Earthquakes migrating upward
• Local ground deformation
• Changes in springs or groundwater
• Gas emissions
• Volcanic tremor

Potential Hazards

An eruption through wet ground or near the coast could begin explosively, creating a maar, tuff ring, ash cloud
and base surges.

Later activity might build a scoria cone and produce basaltic lava flows.

Ancient Volcanoes of the South Island

The South Island contains spectacular volcanic landscapes, but its major volcanic systems are ancient and are not
part of New Zealand’s presently active volcanic arc.

Banks Peninsula

Banks Peninsula near Christchurch was constructed by large overlapping shield volcanoes centred around Lyttelton
and Akaroa.

Erosion and marine flooding carved the old volcanic structures into dramatic harbours, ridges and bays.

Dunedin Volcanic Complex

The hills and Otago Peninsula around Dunedin formed through prolonged volcanic activity millions of years ago.

Lava flows, dikes, volcanic plugs and eroded crater structures remain visible across the landscape.

Why the South Island Is Not Currently Volcanic

Present plate motion beneath the South Island is dominated by oblique collision and sideways movement along the
Alpine Fault rather than the North Island-style subduction that produces an active volcanic arc.

The South Island therefore faces major earthquake, landslide and mountain-building hazards without comparable
modern volcanism.

Historic and Geologically Recent New Zealand Eruptions

New Zealand’s eruption history extends far beyond written European records. Geological deposits, Māori oral
histories, archaeological evidence, diaries, photographs and modern instruments together preserve a complex
volcanic chronology.

Explore major eruptions worldwide:
Historic Volcanic Eruptions Explained.

Māori Relationships with New Zealand’s Volcanic Landscapes

Aotearoa’s volcanoes are not merely geological objects. They are maunga, ancestral beings, sacred places and
central elements of whakapapa, identity, history and tribal relationships.

Māori names, oral traditions and customary practices preserve deep knowledge of volcanic landscapes. This
knowledge should be presented accurately and with respect rather than reduced to decorative mythology.

Tongariro, Ruapehu and Ngāuruhoe

The central volcanic mountains hold profound significance for Ngāti Tūwharetoa and neighbouring iwi.

In 1887, Horonuku Te Heuheu Tūkino IV placed the sacred peaks under protection through an arrangement that helped
establish Tongariro National Park.

Modern explanations increasingly recognise that the transaction was not a simple unrestricted gift of ownership,
but an effort to protect the maunga from division and exploitation.

Taranaki Maunga

Taranaki Maunga is an ancestor and source of identity for the eight iwi of Taranaki.

Colonial confiscation, renaming and land alienation profoundly affected the relationship between tangata whenua
and the mountain.

Current legal and cultural recognition increasingly reflects the maunga’s status as a living ancestral entity
rather than merely a recreational or geological resource.

Rangitoto and Tāmaki Makaurau

Rangitoto erupted within the period of Māori settlement. Oral traditions and archaeological evidence show that
communities lived around the Hauraki Gulf while the island was forming.

The volcanic cones of Auckland were also fortified, cultivated and occupied as pā and settlements. Their terraces
and archaeological remains are part of the cultural landscape.

Tūhua Obsidian

Obsidian from Tūhua/Mayor Island was valued for sharp tools and transported through extensive exchange networks.

Its presence at archaeological sites provides evidence of movement, relationships and trade across Aotearoa.

Mātauranga Māori and Volcano Science

Mātauranga Māori includes place-based knowledge, oral history, environmental observation, tikanga and
relationships accumulated across generations.

Volcanic-risk planning can be strengthened when scientific institutions work respectfully with iwi, hapū and
local communities.

How New Zealand Volcanoes Are Monitored

New Zealand’s volcanoes are monitored through GeoNet, the national geological-hazard monitoring
system supported by scientific institutions and national emergency-management agencies.

Monitoring differs among volcanoes. Frequently active or high-risk systems receive denser instrument networks,
while remote submarine volcanoes may be observed primarily through satellites, regional seismic stations and
research expeditions.

Visual Observations

Scientists use cameras, observation flights, satellites, drones and field visits to document steam, ash,
landslides, crater changes and new vents.

Seismo-Acoustic Monitoring

Seismometers detect earthquakes and volcanic tremor. Acoustic instruments can identify explosions and pressure
waves travelling through the atmosphere.

Different signals may indicate brittle rock fracture, moving fluids, gas release, crater explosions or lahars.

Geochemical Monitoring

Scientists measure sulfur dioxide, carbon dioxide and other gases released from vents, soil and crater lakes.

Water from lakes, springs and fumaroles is analysed for temperature, acidity, dissolved minerals and chemical
changes.

Ground Deformation

GNSS receivers, tiltmeters, precise levelling and satellite radar reveal uplift, subsidence and movement across
volcanic systems.

Deformation may reflect magma accumulation, hydrothermal pressure or fault movement.

Thermal Monitoring

Infrared cameras and satellite sensors measure changes in heat output from crater lakes, fumaroles and active
vents.

Lahar Detection

Ruapehu has specialised systems capable of detecting ground vibration and changes in river conditions associated
with lahars.

Lake Monitoring

Te Wai ā-moe on Ruapehu is monitored for temperature, water level and chemistry. Lake Taupō is monitored for
earthquakes, deformation and changes around the caldera.

Marine Monitoring

Submarine systems require sonar mapping, remotely operated vehicles, water sampling and hydrophone or
ocean-bottom instruments.

New Zealand Volcanic Alert Levels

New Zealand uses a six-level Volcanic Alert Level system ranging from Level 0 to Level 5.

The level describes the volcano’s current state and is designed to communicate activity consistently. It is not a
direct measure of risk at every location.

Alert Levels May Not Change Sequentially

A volcano may change quickly, and an eruption can occur at any alert level. Levels do not necessarily progress
neatly from 0 through 5.

A volcano can also remain at an elevated level for weeks or months without erupting.

Alert Level Versus Hazard Zone

A Volcanic Alert Level describes activity at the volcano. Risk depends on where a person is located, what hazards
are possible and how long they remain exposed.

Someone standing beside an active vent at Level 1 may face greater danger than someone hundreds of kilometres away
during a larger eruption.

Volcanic Aviation Colour Codes

Aviation colour codes communicate the potential threat of volcanic activity to aircraft.

Aviation colour codes should not be used as hiking or ground-access advice. Ground hazards may remain severe even
when no high-altitude ash cloud is present.

Earthquake Swarms Beneath New Zealand Volcanoes

An earthquake swarm is a sequence containing many earthquakes without one clearly dominant mainshock.

Swarms are relatively common within the Taupō Volcanic Zone and may occur beneath Taupō, Okataina, Rotorua,
Ruapehu, Tongariro and other systems.

Possible Causes

• Magma forcing fractures open
• Movement of hot water and gas
• Pressure changes within geothermal reservoirs
• Fault movement caused by crustal extension
• Adjustment after larger earthquakes

Does a Swarm Mean an Eruption Is Coming?

Not necessarily. Many swarms decline without an eruption.

Scientists examine earthquake depth, migration, frequency and waveform together with deformation, gas and thermal
observations.

A shallow migrating swarm combined with rapid uplift and changing volcanic gas would generally be more concerning
than an isolated cluster with no other changes.

Can New Zealand Eruptions Be Predicted?

Volcanologists can sometimes forecast increasing eruption probability, but they cannot normally predict the exact
time, vent, size and sequence of an eruption.

Forecasting Cone Volcanoes

Rising magma may generate earthquake swarms, tremor, ground deformation and gas changes at Ruapehu, Tongariro,
Taranaki or Whakaari.

Hydrothermal eruptions remain difficult because shallow pressure seals may fail suddenly.

Forecasting Caldera Eruptions

Taupō or Okataina could experience prolonged unrest involving earthquakes and deformation before a major magmatic
eruption.

However, calderas may also show repeated unrest without eruption, making interpretation difficult.

Forecasting Monogenetic-Field Eruptions

In Auckland or Northland, scientists must determine where a completely new vent may open.

Warning could begin with deep earthquakes that gradually migrate upward as magma approaches the surface.

Volcano Preparedness in New Zealand

Volcano preparedness depends on location. Residents near Ruapehu face different hazards from people living in
Auckland, Rotorua, Taupō or Taranaki.

Before Volcanic Unrest

• Learn whether your home, workplace or school lies in an official hazard zone.
• Identify evacuation routes and safe locations.
• Keep water, food, medication, flashlights and radios available.
• Store suitable particulate masks and sealed eye protection.
• Plan for pets, livestock and people needing assistance.
• Know how to protect water tanks and ventilation systems from ash.
• Follow GeoNet, emergency-management and council information.

During Volcanic Unrest

• Read complete official bulletins rather than social-media summaries.
• Expect roads, tracks and recreational areas to close.
• Prepare to leave early when evacuation is advised.
• Stay away from crater lakes, fumaroles and unstable slopes.
• Do not enter exclusion zones to photograph activity.

During Ashfall

• Remain indoors when possible.
• Close doors, windows and ventilation openings.
• Wear a well-fitting particulate mask outdoors.
• Protect eyes with goggles or sealed glasses.
• Avoid unnecessary driving.
• Keep ash out of drains and machinery.
• Protect livestock feed and water.
• Remove roof ash only when safe and officially recommended.

During a Lahar Warning

• Move out of river valleys and channels.
• Travel to higher ground.
• Never attempt to cross a moving lahar.
• Remember that lahars may arrive far from the crater.

During an Evacuation

• Leave when instructed rather than waiting for visible eruption signs.
• Use designated routes.
• Carry identification, medication and essential supplies.
• Do not return until authorities reopen the area.
• Check on vulnerable neighbours when it is safe.

Volcano Tourism in New Zealand

New Zealand’s volcanoes attract millions of visitors to hiking tracks, ski areas, geothermal parks, crater lakes,
volcanic islands and cultural landscapes.

Tourism access does not prove that a volcano is inactive or permanently safe.

Essential Visitor Safety

• Check GeoNet, Department of Conservation and local authority updates.
• Respect track closures and exclusion zones.
• Use experienced guides where appropriate.
• Prepare for sudden alpine weather.
• Carry sufficient water, clothing and communication equipment.
• Move quickly through marked lahar or eruption-hazard zones.
• Follow tikanga and guidance from mana whenua.

How Volcanoes Shape New Zealand’s Ecosystems

Volcanic eruptions destroy vegetation and habitats, but they also create new land, soils, lakes and ecological
opportunities.

Volcanic Soils

Weathering of ash and lava releases minerals and creates soils that may become highly productive.

Volcanic soils support forestry, horticulture, pastoral farming and native ecosystems across much of the North
Island.

Ecological Succession

Fresh lava and ash are gradually colonised by microorganisms, lichens, mosses, grasses, shrubs and forest.

Rangitoto provides a clear example of pōhutukawa forest developing across young basaltic lava.

Hydrothermal Habitats

Hot springs and geothermal soils support heat-tolerant microorganisms adapted to acidity, sulfur and extreme
temperatures.

Volcanic Lakes

Lakes formed in calderas and explosion craters create aquatic habitats but may experience changes in chemistry,
temperature and sediment following unrest or eruptions.

Long-Term River Effects

Pumice and ash may block or redirect rivers, alter floodplains and continue moving through catchments for decades
after an eruption.

Volcanic Ash and New Zealand Agriculture

Volcanic soils support productive farming, but fresh ashfall can become a severe agricultural emergency.

Immediate Effects

• Buried pasture and crops
• Contaminated stock water
• Reduced feed availability
• Damage to machinery
• Blocked irrigation equipment
• Transport disruption
• Animal breathing and eye problems

Fluorine Hazard

Some volcanic ash carries soluble fluorine compounds. Livestock consuming contaminated grass or water may develop
poisoning even where ash thickness is limited.

Long-Term Recovery

Thin ash deposits may eventually improve some soils, but recovery depends on ash chemistry, thickness, rainfall,
drainage and the condition of underlying land.

Thick deposits may require years of rehabilitation or abandonment.

Can New Zealand Volcanoes Affect Climate?

A sufficiently large explosive eruption can affect climate if sulfur dioxide reaches the stratosphere and forms
sunlight-reflecting sulfate aerosols.

Most eruptions at Ruapehu, Tongariro or Whakaari are too small to produce a major global climate effect.

Very large Taupō or Okataina eruptions could affect regional or global climate temporarily, depending on sulfur
release, eruption duration and atmospheric circulation.

Volcanic cooling is temporary because aerosols gradually settle from the atmosphere. It does not reverse the
long-term warming effect of persistent greenhouse-gas accumulation.

What Could New Zealand’s Next Eruption Look Like?

No one can identify with certainty which New Zealand volcano will erupt next.

Practical planning considers multiple realistic scenarios rather than focusing only on the largest possible
disaster.

Scenario 1: A Small Whakaari Explosion

A hydrothermal or magmatic explosion could produce ash, ballistic blocks and pyroclastic surges across the crater
and surrounding waters.

Scenario 2: Ruapehu Crater Eruption

An eruption through Te Wai ā-moe could eject water, ash and rocks and generate lahars down several valleys.

Scenario 3: Tongariro Reactivation

Te Māri, Red Crater or another vent could produce a short explosive eruption affecting hiking tracks and nearby
transport routes.

Scenario 4: Taranaki Eruption

Earthquake swarms and deformation could precede dome growth, explosions, ashfall, lava flows or lahars affecting
western North Island communities.

Scenario 5: New Auckland Vent

Magma could open beneath a suburb, harbour or industrial zone, beginning with explosive magma-water interaction
and progressing to scoria-cone growth and lava flows.

Scenario 6: Taupō Unrest Without Eruption

Earthquakes and uplift could continue for months while creating disruption and concern without magma reaching the
surface.

Scenario 7: Moderate Taupō or Okataina Eruption

A localised pumice eruption or lava dome could produce serious regional ashfall without approaching the size of a
supereruption.

Scenario 8: Submarine Kermadec Eruption

A remote eruption could generate pumice rafts, hydrothermal plumes and aviation or navigation warnings before the
source is directly observed.

New Zealand Volcano Myths and Misinformation

Myth: Every Taupō Earthquake Means a Supereruption Is Starting

Earthquake swarms and deformation occur during volcanic and tectonic unrest. Most episodes decline without an
eruption.

Myth: Taupō’s Next Eruption Must Be Enormous

Taupō has produced eruptions across a vast range of sizes. Smaller events are much more common than Oruanui-scale
supereruptions.

Myth: Dormant Means Extinct

Taranaki and Auckland have not erupted during European settlement, but both remain potentially active systems.

Myth: GeoNet Can Predict the Exact Day of an Eruption

Monitoring can identify changing unrest and support probabilistic forecasts, but it cannot normally specify an
exact eruption time.

Myth: A Level 0 Volcano Is Completely Safe

Hydrothermal activity, gas, landslides, lahars and sudden eruptions may remain possible at low alert levels.

Myth: Whakaari Was Safe Because Tourists Had Visited Before

Repeated previous access did not remove the inherent risk of standing inside an active hydrothermal crater.

Myth: Ngāuruhoe Is a Separate Volcanic System

Ngāuruhoe is the youngest major cone and active vent within the broader Tongariro volcanic complex.

Frequently Asked Questions About New Zealand Volcanoes