USGS/Cascades Volcano Observatory, Vancouver, Washington
DESCRIPTION:
New Zealand Volcanoes and Volcanics
- New Zealand Volcanoes
- Auckland Volcanic Field - Mount Wellington - Rangitoto
- Egmont Volcano - Mount Taranaki
- Kermadec Islands - Raoul Island
- Okataina Volcanic Center and Haroharo Caldera
- Rotorua Caldera
- Ruapehu
- Tauhara Volcano and Tauhara Geothermal Field
- Taupo Caldera
- Tonagariro
- White Island
-
[Map,20K,InlineGIF]
Location Map, Major New Zealand Volcanoes
From:
Simkin & Siebert, 1994,
Volcanoes of the World
-
New Zealand contains the world's strongest concentration of youthful rhyolitic volcanoes,
and voluminous ignimbrite
sheets blanket much of North Island. Associated
caldera formation
places this region at the top of the list, along with
Indonesia,
of volcanoes with caldera as the primary morphologic feature. A strong emphasis
on tephrochronology has documented the
Quaternary
volcanic history of this active island in unusual detail:
No other region has a higher proportion (74 percent)
of its large eruptions in the BC age range. ...
-
The earliest historically-dated eruption was at White Island in 1826. ...
-
Much of the region north of New Zealand's North Island is made up of
seamounts
and small islands, including 16 submarine volcanoes. The region has the largest number of
eruptions dated by SOFAR technology, or underwater sound. No other region has a higher
proportion of eruptions building new islands (21 percent, all in Tonga and the Kermadecs) or
producing pyroclastic flows (27 percent, mostly on New Zealand's North Island).
From:
New Zealand Institute of Geological and Nuclear Sciences Limted, Website, 2001
-
The New Zealand area is characterised by both a high density
of active volcanoes and a high frequency of
eruptions. Volcanic activity in New Zealand occurs
in six areas, five in the North Island
and one offshore in the Kermadec Islands.
-
Volcanoes in New Zealand are not randomly scattered, but are grouped
into areas of more intensive and long-lived activity, whose position
(and the composition of the lavas erupted)
can be related to the large-scale movement of the tectonic plates in the New Zealand region.
Most New Zealand volcanism in the
last 1.6 million years has occurred in the
Taupo Volcanic Zone (TVZ). The zone is an elongate area
that extends from
White Island to Ruapehu.
The Taupo Volcanic Zone is extremely active on a world scale: it includes three frequently
active cone volcanoes
(Ruapehu, Tongariro/Ngauruhoe, White Island), and two of the
most productive calderas in the world (Okataina and
Taupo).
-
here are three major types of volcano in New Zealand.
-
-
Volcanic fields
such as Auckland and Northland,
are where small eruptions occur over a wide geographic area, and are spaced over long
periods of time (thousands of years).
Each eruption builds a new single new volcano, which does not erupt again.
Mount Eden and
Rangitoto Island are examples in Auckland.
-
-
Cone volcanoes such as Ruapehu,
Egmont and Ngauruhoe
are characterised by a succession of small-moderate eruptions from one
location. The products from the successive eruptions
over thousands of years build the cones.
-
-
Caldera volcanoes such as
Taupo and Okataina (which includes Tarawera)
have a history of infrequent but moderate-large eruptions. The
caldera forming eruptions create super craters
10-25 kilometers in diameter and deposit cubic kilometres of ash and pumice.
Auckland Volcanic Field - Mount Wellington - Rangitoto
|
From:
The Volcanoes of Auckland Website, June 2001
-
It is thought that
Auckland's volcanoes first began to appear between 60 000 and 140 000 years ago,
starting with the eruptions of the Domain and Albert Park.
The largest and most recent eruption was Rangitoto, about 600 years ago.
The Auckland Volcanic Field is expected to have a total life of approximately
one million years, so potentially there is a lot of life left in the field yet. ...
-
The Auckland Volcanic Field is comprised of
monogenetic volcanoes
which means it is unlikely that Mount Wellington or any of the existing volcanoes
will erupt again. The next eruption will probably occur in a new location. ...
-
Mount Wellington is the most recent site of
mainland activity (about 9,000 years ago).
Scoria and lava deposits overlie tuff
deposits from early eruptions. The 100
metre scoria cone was produced from lava
fountaining from 3 vents in the crater.
Lava flows streamed from a number of
vents to Penrose and then on to the
Manukau Harbour forming almost 6-kilometer-long
lava flows. ...
Mount Wellington is the largest
scoria cone
(volume of scoria) and the second youngest volcano in the
Auckland Volcanic Field. ...
-
Rangitoto is the largest, most recent and
least modified volcano of the Auckland
Volcanic Field. It forms a near symmetrical
cone at the entrance to the Waitemata
Harbour.
From:
Geological Society of New Zealand Website, 2001
-
Auckland City is built upon an active
volcanic field
created over the last 150,000 years,
with the youngest volcano
Rangitoto being formed just 600 years ago.
Eruptions from 48
small basalt volcanoes have produced
an attractive landscape of cones, craters, and lava
flows. Today, these remnants provide
us with a unique opportunity to learn about our
city's volcanic past and the processes that form volcanoes.
From:
Geological Society of New Zealand Website, 2001
-
Many of the landforms and soils of
Auckland, North Shore and Manukau
Cities have been produced by basaltic
volcanism in just the last 150,000 years,
with the latest eruption, Rangitoto, being
witnessed by the Maori 600 years ago.
While the older (0.5 to 1.5 million years
ago) volcanoes of the Franklin basaltic
field around the Pukekohe / Bombay area
are extinct, further eruptions from the
younger Auckland field are considered
likely.
-
The magma that fed Auckland's
volcanoes originated some 100 kilometers below the surface. Periodically, a large buoyant body
of molten magma rose up through the overlying rocks to erupt at the surface. Near the
surface, the hot gas-charged magma was forced out by the pressure of escaping gases.
- Auckland's volcanoes all had short lives and have been once-only eruptions. Each volcano
was formed during a single eruption, or sequence of short eruptions, generally lasting no
longer than a year or two. It is possible however for a scoria cone or tuff ring to form in a
matter of days. Once the magma body was exhausted, eruptions ceased and the
subsurface plumbing solidified.
Egmont Volcano - Mount Taranaki
|
From:
New Zealand Institute of Geological and Nuclear Sciences Limted, Website, 2001
-
The western 1.500 square kilometers of
Taranaki is a volcanic landscape
that has been constructed from
the products of volcanic
eruptions principally derived from
Mt Taranaki/Egmont (hereafter
referred to as Egmont Volcano).
Egmont Volcano last erupted
about 200 years ago at the
culmination of eight eruptions in
the preceding 300 years.
Deposits around the base of the
Volcano record intermittent
volcanic activity at this site for
the last 130,000 years. Whilst
the eruptions have not occurred
at regular intervals there has been a
moderate or major sized eruption on average every 340 years with
numerous smaller events at more frequent intervals.
There is therefore no evidence to suggest Egmont
Volcano has finally ceased erupting and has become extinct.
Rather it must be regarded as an active
volcano in a state of quiescence and is one of a
number of volcanoes in New Zealand where future
eruptions are to be expected.
Egmont Volcano is of the "slumbering" type that
could begin renewed activity in the next 100 years. ...
-
One of the characteristic features in the history of Egmont Volcano has been the irregular occurrence of enormous landslides. On three
occasions, twice within a very short period of geological time, former Egmont cones have collapsed to the northeast, southeast and west.
In each instance extremely large volumes of material greater than 3.5
cubic kilometers flowed across the landscape to travel over 40 kilometers distance,
reaching the present Taranaki coastline. These rapid landslide events are technically referred to as volcanic debris avalanches. They have
created the distinctive mounds or hummocks on the lowlands surrounding the Volcano. Near to source these landslides envelope
everything in their path, even flowing uphill if there is a barrier in the relief. However beyond distances of about 20 km the landslide debris is
guided by any pre-existing dissected relief and flows along channels or valleys. ...
-
Lava flows from Egmont Volcano have seldom extended beyond 4
kilometers distance for their source crater, and the most distant is the
Dawson Falls lava flow, 5 kilometers from its presumed source. Thus all
lava flows extruded in the entire history of volcanic activity at
Egmont Volcano have never extended beyond the area now
delineated as Egmont National Park, an area largely unpopulated.
In the past, nearly all of the lava flows have been erupted from the
central vents of Egmont crater and Fanthams Peak. These vents
are regarded as the likely source-areas for future lava flows in
future eruptions of Egmont Volcano.
Kermadec Islands - Raoul Island
|
From:
New Zealand Institute of Geological and Nuclear Sciences Limted, Website, 2001
-
The Kermadec Islands are the summits of large volcanoes
that have been built up on the crest of the Kermadec Ridge, and have emerged
above sea level. The ridge stretches for 600 to 700 kilometers
north-north-east from about 33oS 180ooS 178oW, and has
been upraised by the ongoing collision between the Pacific and Australian plates.
-
The Kermadec Islands, 750 to 1000 kilometers north-north-east
of New Zealand, are mainly of volcanic origin. They are uninhabited,
except for a weather station manned by a handful of people on
Raoul Island (previously known as Sunday Island), the largest and
most northerly island in the group. All the islands
are scientific reserves for the protection of fauna and flora. They
have a moist subtropical climate, and as a result vegetation
normally recovers quickly (in tens of years) after being
damaged by volcanic activity. However, a very large eruption could well destroy the
seed source, and regrowth of vegetation would then be very slow.
The islands are administratively part of New Zealand, and any risks that
result from eruptions there are accordingly the Government's
responsibility to assess and reduce, if possible.
-
All these volcanoes lie along the
zone of collision of two of the
major structural plates of which
the Earth's crust is composed, the Pacific plate to the east,
and the Australian plate to the west.
The line of collision is marked by the
succession of deep ocean trenches which
characterise this part of the south-west pacific,
the Tonga Trench in the north, the Kermadec Trench in
the centre, and the Hikurangi Trench in the south,
off the coast of the North Island of New Zealand.
Along this line, the Pacific plate is being forced
beneath the overriding Australian plate as a result of
the relentless pressure of convergence of these two
huge regions of the Earth's surface. The rate at which
this process is taking place is relatively high,
about 7 centimeters per year on average (although it is not yet known
whether the process is continuous, or whether it
proceeds as a series of sudden jumps, perhaps
associated with large earthquakes).
Earthquakes occur on the upper surface of the Pacific plate down to
depths of more than 600 kilometers, as it is forced
down at a steep angle below the overriding Australian plate,
which is itself buckled upwards by the pressure of
collision forming structural highs, two of which are the
Tonga and Kermadec Ridges. The line of volcanoes
formed when rock melted by the heat of collision,
over a range of depths at which the increasing temperature
outweighed the effect of increased pressure
(which tends to prevent melting), then rose under its
own buoyancy through denser overlying rock to
intrude the upper crust. The primary melting process,
shown by earthquakes taking place in the roots of
the volcanoes, occurs at depths of about 100 kilometers
below the surface.
-
-
The northernmost known volcanic centre in the Kermadecs is
Raoul Island, which is the summit of a large submerged massif about 35 kilometers
by 20 kilometers, with its long axis aligned north-east,
slightly inclined to the overall trend of the Kermadec Ridge.
It is possible, however, and
indeed likely, that there are submarine volcanoes,
as yet undiscovered, further north along the ridge,
which rises in several places to within
500 metres of the surface.
Raoul Island itself, the largest of the Kermadec Islands,
is an anvil-shaped island, about 30 km2 in area, with a
maximum length of about 10 kilometers
in an east-west direction along the north coast,
and about 6 kilometers from north to south. The island
has undergone many changes as a result of eruptions
during the past few thousand years, and as a result of earlier eruptions. It now
contains a large central depression, a little over 3 kilometers
east-west by about 2 kilometers north-south, formed largely by subsidence immediately
after large eruptions.
This type of structure, resembling a very large volcanic crater,
is known as a caldera. Just west of Raoul Caldera, and
almost touching it at one point,
is Denham Bay, a second caldera (also a little over 3 kilomters long,
but in a north-south direction, by rather less
than 3 kilometers wide), which has been flooded by the sea.
Okataina Volcanic Center and Haroharo Caldera
|
From: Newhall and Dzurisin, 1988, Historical Unrest at Large Calderas of the World:
USGS Bulletin 1855
-
Haroharo Caldera and Okataina Volcanic Center lie in the northern half of the
Taupo Volcanic Zone (TVZ), a region of intense volcanic and
geothermal activity.
The TVZ is about 250 kilometers long and up to 50 kilometers wide; more than
16,000 cubic kilometers of lavas and pyroclastics have been erupted from the TVZ since
volcanism commenced in the late Pliocene. Phyolites were erupted from the central part of the
TVZ, a deep volcano-tectonic depression in which eruptions were associated with ring
structures, cauldron subsidence, and calderas. A complex system of normal faults runs through
the TVZ, and andesite volcanoes are found near its ends (Healy, 1962, 1964; Rogan,
1982).
-
Haroharo Caldera and Okataina Volcanic Center have been the sites of repeated
large silicic eruptions during the past 300,000 years or more (Cole, 1970, 1979; Wilson and
others, 1984). At least 20 additional explosive eruptions have occurred within the past
50,000 years (Froggatt, 1982), those in the past 20,000 years along fissures (Wilson
and others, 1984). ... Recent eruptions have been from Tarawera, located on the
southern margin of the caldera, and from thermal areas within and adjacent to the caldera. A
major prehistoric eruption of Tarawera, the Kaharoa eruption of ca. A.D. 1250,
produced thick pyroclastic deposits and four rhyolite domes at the summit of Tarawera
that are now exposed in cross section along the 1886 rift (Cole, 1970).
From: Newhall and Dzurisin, 1988, Historical Unrest at Large Calderas of the World:
USGS Bulletin 1855
-
Rotorua Caldera lies near the western margin of the Taupo Volcanic Zone, west of
Okataina Volcanic Center.
-
Rotorua Caldera formed as a result of eruption of the 200 cubic kilometer (dense-rock
equivalent) Mamaku ignimbrite. Subsequent lava domes in the calder, from 1 to 10 cubic
kilometers in volume, have not been dated. No eruptions (other than hydrothermal explosions)
are known within the past 10,000 years, but the Rotorua-Whakarawarewa area is known for
numerous hot springs, geysers, and other geothermal features that support a significant tourist
industry.
From:
Smithsonian Institution, Global Volcanism Network Website, September 2001
-
Ruapehu, (2,779 meters), one of New Zealand's most active volcanoes,
is a complex stratovolcano constructed during at least four cone-building episodes.
The 110 cubic kilometer volcanic massif is elongated in a NNE-SSW direction and is
surrounded by another 100 cubic kilometer ring plain of volcaniclastic debris,
including the Murimotodebris-avalanche deposit on the NW flank.
A single historically active vent, Crater Lake, is located in the broad summit region,
but at least five other vents on the
summit and flank have been active during the Holocene.
Frequent mild-to-moderate explosive eruptions have occurred in historical
time from the Crater Lake vent.
Lahars produced by phreatic eruptions from the
summit crater lake are a hazard to a ski area on the upper flanks and to lower river valleys.
From:
New Zealand Institute of Geological and Nuclear Sciences Limted, Website, 2001
-
Ruapehu volcano is the southernmost of the large
active volcanoes of the North Island. Rising to
2,797 meters (9,175 feet),
Mount Ruapehu is the highest
mountain in the North Island and the most recent of the
North Island volcanoes to have erupted. Ruapehu
is located at the southern end of the Taupo Volcanic Zone (TVZ),
a spreading segment of the Earth's
crust and the source of spectacularly explosive eruptions
over the last 2 million years. Subsidence in the
central axis of the TVZ has led to prominent
active faults developing to the east and west of Ruapehu
volcano, which are downthrown towards the mountain.
These faults mark the boundary of the TVZ in this
region, which terminates 20 kilometers south of Ruapehu's summit.
-
Ruapehu is largely comprised of the volcanic rock andesite.
Accumulations of andesite lava flows
interbedded with fragmental rubble radiate from the
summit region forming a
stratovolcano
that rises
2,000 meters from the surrounding lowlands.
As stratovolcanoes build up they become steep and have a
propensity to collapse generating debris avalanches
and lahars that spread outwards onto the
surrounding lowlands. These lowlands form a
roughly circular apron of fragmented rocks (volcaniclastics)
termed the ring plain, mainly derived from debris avalanches
and lahars, but also including some river
(fluvial) and glacial deposits. Mantling the lowlands
are various thicknesses of volcanic ash forming the
parent material of most of the soils in the region.
Due to the dominantly westerly wind direction, ash
thickness for a given distance from the summit is
always considerably greater to the east than to the
west.
-
Dominating the summit area is a crater lake which,
when full to overflowing contains 8-10 million cubic meters of
acid waters. During historical eruptions (in 1945 and 1995)
the lake water has been ejected out of the
crater and onto surrounding glaciers, and/or propelled
across the outlet and into the Whangaehu
catchment. Displacement of lake water during
these eruptions was followed by dome extrusion and/or dry
ash eruptions. When water again accumulates in the
summit crater, phreatomagmatic (or wet) eruptions
occur with accompanying water expulsion creating
lateral surges and lahars. Lahars generated in such a
way are one of the devastating and hazardous of volcanic events.
Throughout history, lahars have been
responsible for much loss of life in the countries of
the Pacific margin, including New Zealand.
Tauhara Volcano and Tauhara Geothermal Field
|
From: Newhall and Dzurisin, 1988, Historical Unrest at Large Calderas of the World:
USGS Bulletin 1855
-
Tauhara Volcano is a complex of five dacite domes of Late Pleistocene age (Lewis,
1968). Tauhara lies 2-3 kilometers outside the northeast rim of Taupo Caldera,
along a postulated deep-seated northeast-trending fracture that bounds the east side of the
caldera (Wilson and others, 1984). The exact age of Tauhara is not known; its minimum
age is 9,000 years (Lewis, 1968).
From: Newhall and Dzurisin, 1988, Historical Unrest at Large Calderas of the World:
USGS Bulletin 1855
-
Taupo Caldera is a poorly defined caldera within the central graben of the southern
Taupo Volcanic Zone. Ring fractures are partly hidden by Lake Taupo
(Northey, 1982; Wilson and others, 1984). Gravity data suggest that the caldera is
deepest near the northernmost point of Lake Taupo, but this is poorly constrained because the
lake makes gravity measurements difficult (Rogan, 1982). Rhyolite domes occur within
and around the caldera ...
-
Lake Taupo occupies the center of an approximately 40-kilometer-diameter basin that has
been the site of many rhyolite eruptions during the past 10,000 years (Wilson and others,
1984; Wilson and Walker, 1985; Houghton and Wilson, 1986; Nairn and Wood, 1986). At least
three major ignimbrites were produced between 330,000 years B.P. and 230,000 years B.P. No
major pyroclastic eruptions are recognized between 230,000 years B.P. and 50,000 years B.P.,
but at least five rhyolite eruptions occurred between 50,000 years B.P. and 20,000 years B.P..
A 10,000-year hiatus followed the last of those eruptions, before the present sequence of
eruptive activity began about 10,000 years ago. A series of ten plinian or subplinian
pyroclastic eruptions climaxed with the exceptionally violent Taupo Pumice eruptions
about 1,800 years ago (90+ cubic kilometers bulk volume) (Healy and others, 1964; Wilson and
others, 1980; Froggatt, 1981b, c; Wilson and Walker, 1985; Wilson, 1985). Those eruptions
are thought to have been from vents near the Horomatangi Reefs (Walker, 1980);
the deepest point in the lake (164 meters) is just south of the reefs.
From:
Smithsonian Institution Global Volcanism Program Website, 2003
-
Tongariro is a large
andesitic volcanic massif,
located immediately northeast of Ruapehu volcano, that is
composed of more than a dozen composite cones
constructed over a period of 275,000 years. Vents
along a northeast-trending zone extending from
Saddle Cone (below Ruapehu volcano) to Te Mari crater
(including vents at the present-day location of Ngauruhoe)
were active during a several hundred year
long period around 10,000 years ago, producing the
largest known eruptions at the Tongarioro complex
during the Holocene.
North Crater stratovolcano,
one of the largest features of the massif, is truncated by
a broad, shallow crater filled by a
solidified lava lake
that is cut on the northwest side by a small explosion
crater. The youngest cone of the complex,
Ngauruhoe, has grown to become the highest peak of the
massif since its birth about 2,500 years ago.
The symmetrical, steep-sided Ngauruhoe, along with its
neighbor Ruapehu to the south, have been
New Zealand's most active volcanoes during historical time.
From:
Smithsonian Institution Global Volcanism Program Website, 2001
-
The uninhabited 2 x 2.4 kilometer White Island (321 meters)
is the emergent summit of a 16 x 18 kilometer
submarine volcano.
The island consists of two overlapping
stratovolcanoes;
the summit crater appears to be breached to the SE because the shoreline
corresponds to the level of several notches in the SE crater wall.
Intermittent steam and tephra eruptions have occurred
throughout the short historical period, but its activity also
forms a prominent part of Maori legends.
From:
New Zealand Institute of Geological and Nuclear Sciences Limted, Website, 2001
-
White Island is the northernmost
active volcano in the Taupo Volcanic Zone -
a 250-kilometer-long
zone of intense volcanism that
marks the boundary of the
Australian and Pacific tectonic
plates. Scientists from the
Institute of Geological & Nuclear
Sciences Limited are regular
visitors to the privately-owned
island, which attracts an
ever-increasing number of tourists.
Sitting 48 kilometers offshore, the island
has been built up by continuous
volcanic activity over the past
150,000 years. About 70 percent
of the volcano is under the sea,
making this massive volcanic
structure the largest in New Zealand.
-
The island has a history of long periods of continuous
hydrothermal activity and steam release, punctuated by small-to-medium eruptions.
Between 1976 and 1993 White Island was more
active than at any time in the past few hundred years, and ash from its 1998 eruptions
was recorded as far inland as Rotorua.
The volcano's activity is often visible to people in
Bay of Plenty with gas and ash plumes rising as
high as 10 kilometers on clear, still days.
Craters and fumaroles on the island continually
emit gases at rates of several hundred to several thousand tonnes per day. The gases are
mostly steam, carbon dioxide and sulphur dioxide,
with small quantities of chlorine and fluorine. Acid gases combine with water in the
steam to form acid droplets that can sting the eyes and skin,
and can affect breathing. The acid can also damage cameras, electronic
equipment and clothes. In spite of its hostile environment,
the island is host to a number of bird species including a gannet colony.
-
The upper slopes of the island, which rises to a height of 321 meters,
are steep and deeply eroded. A sulphur mining venture on the island
stopped abruptly in 1914 when part of the crater wall collapsed
and a landslide destroyed the sulphur mine and miners' village. Twelve lives
were lost. Mining resumed again in the 1920s and the
remains of buildings from that era are a tourist attraction. The sulphur was used to
make fertiliser, for export as sulphur ore, and for the manufacture of sulphuric acid. ...
-
White Island is the summit of a large
(16 by 18 kilometers)
submarine volcano
which has grown up from the sea floor at
300 meters to 400 meters depths.
Only half the height and a very small proportion of the volume
of this volcano are above sea level.
The main crater was formed in prehistoric times, apparently
by the collapse of three overlapping roughly circular subcraters.
The eastern subcrater was
formed first, and now contains only minor hot spring activity.
The central subcrater contains the Donald Mount fumaroles
(vents emitting steam and hot gases), and the Noisy Nellie and Donald Duck craters
and fumaroles. The western subcrater contains most of
the eruption sites that have formed since 1960
and has been the main focus of activity during the island's recorded history.
Deep pits mark the sites of recently active vents.
Most of the present main crater floor lies less than 30 meters above sea level,
and has an irregular surface covered by mounts of avalanche debris from the 1914 disaster.
Return to:
[New Zealand Volcanoes and Volcanics Menu] ...
[Thermal and Geothermal Activity Menu] ...
URL for CVO HomePage is:
<http://vulcan.wr.usgs.gov/home.html>
URL for this page is:
<http://vulcan.wr.usgs.gov/Volcanoes/NewZealand/description_new_zealand_volcanoes.html>
If you have questions or comments please contact:
<GS-CVO-WEB@usgs.gov>
02/06/03, Lyn Topinka