A large submarine volcano located at the southern end of the Tonga arc
rises to within 385 m of the sea surface. Known informally as Volcano
19, the basaltic to basaltic-andesite seamount contains two calderas,
a 3.5 x 2.5 km wide outer caldera and a 1.9-km-wide inner caldera on the
west side of the volcano. A central cone complex lies in the center of
the outer caldera, east of the inner caldera. Two large hydrothermal fields
are located near the summit of the central cone complex and at the base
of the southern wall of the western inner caldera. Large high-temperature
chimney vents discharge clear fluids and black smoke.
UNNAMED
Volcano Number: 0403-01=
Last Known Eruption: Unknown
Last Known Eruption: 1932
During an eruption in 1907 from an unnamed submarine volcano pyroclastic
material was ejected to 100 m above the sea surface, and pumice rafts
were produced. The eruption was approximately located on Admiralty Chart
2421 at a point 48 km SW of Tongatapu Island, along the Tofua volcanic
arc. Tongatapu is located at the southern end of a chain of coral islands
paralleling the Tofua volcanic arc on its eastern side. The reported
location of the 1907 eruption corresponds to sloping terrain at 1800
m depth on a 1982 bathymetric map, but a seamount of about 500 m depth
is located about 10 km to the NE. A second eruption from this area was
reported in late 1932.
UNNAMED
Volcano Number: 0403-03=
Last Known Eruption: Unknown
Steam
clouds and discolored water from a submarine eruption were observed
in January 1999.
This unnamed submarine volcano is located 35 km NW of the Niu Aunofo
lighthouse on Tongatapu Island.
The volcano, whose first documented eruptions took place in 1911 and
1923, was constructed at the southern end
of a submarine ridge segment of the Tofua volcanic arc extending NNE
to Falcon Island.
An ephemeral island was formed during this eruption in 1999;
prior to this the summit was 13 m beneath the sea surface. Photo by B. Hutchins,
1999 (published in Taylor, 1999) /GVN
Last Known Eruption: 1999
An unnamed submarine volcano is located 35 km NW of the Niu Aunofo lighthouse
on Tongatapu Island. Tongatapu is a coral island at the southern end
of an island chain paralleling the Tofua volcanic arc on the east. The
volcano, whose first documented eruptions took place in 1911 and 1923,
was constructed at the southern end of a submarine ridge segment of
the Tofua volcanic arc extending NNE to Falcon Island. Prior to an eruption
in 1999, when an ephemeral island was formed, the volcano rose nearly
1400 m to within 13 m of the sea surface.
Location
map of the southern part of the central region of the Tonga Platform
and Tofua Volcanic Arc
showing the site of the January 1999 volcanic activity in Tonga.
Note the NNE-SSW trending trough-like feature that separates the volcanic
arc and the Tonga Platform in this region Courtesy of Paul Taylor/GVN
The Tonga Chronicle noted that the activity was first reported
to Tonga Defense Services on 8 January by Carl Riechelmann, who had seen
a plume coming from the site. On 12 January 1999 the Tonga Defence Services
flew a photographic
mission to record the reported appearance of a new island. Three days
later the island had disappeared, but the site was
still emitting smoke and fumes.
FALCON ISLAND or Fonaufo'ou in Tongan
Volcano Number: 0403-05=
Last Known Eruption: 1936
Falcon
Island is seen from the SE showing the active crater through the SE
breach; a steam column is dispersed
to the NW by dominant SE Trade Winds. The ephemeral Falcon Island in
the central part of the Tonga Islands was
named after the British vessel H.M.S. Falcon, which reported a shoal
in 1865.
Falcon Island has been the site of island-forming eruptions on at least
two occasions since the 19th century.
By 1949 the island had eroded beneath sea level, but the summit of the
volcano remains at shallow depths. Photo by A. Thompson
(published in Taylor and Ewart, 1997)/GVN.
We
recently found this page from 1889 on the net. More to be found here: http://www.jstor.org/pss/1801346
It was first sighted by the crew of one of Her Majesty Queen Victoria's
ships in 1865, when it was given this name,
but another British ship which was in the same locality twelve years
later saw nothing but smoke rising from the sea
where the island was reputed to be. When Falcon surfaced again in
1885, it was formally annexed by King George I
of Tonga, but once again it sank slowly and by 1898 nothing more
than a breaking shoal was visible.
This time the island remained submerged for nearly thirty years
until in October 1927 it shot up again with such vigour
that by 1930 it finally attained four-hundred-and-seventy-five
feet, its greatest height yet recorded. (1952) http://mod.nic.in/samachar/dec1-01/html/ch14.htm
TOFUA
Volcano Number: 0403-05=
Last Known Eruption: 1936
Steam
rises from Lofia cone on the north side of the caldera lake of Tofua
volcano in this 1990 aerial photograph.
Recent tephra from pyroclastic cone mantles the caldera rim to the NW.
The walls of the 5-km-wide caldera drop
steeply about 500 m. Three post-caldera cones were constructed at the
northern end of a cold fresh-water
caldera lake, whose surface lies only 30 m above sea level. Tofua was
seen in eruption in 1774 by Captain Cook,
and Captain William Bligh landed on the island in 1789, just after the
renowned mutiny on the "Bounty."
Aerial photo by Tonga Ministry
of Lands, Survey, and Natural Resources, 1990 (published in Taylor and
Ewart, 1997)/GVN.
Tofua is a nearly circular island 9.5 x 7.1 km in diameter. The flanks
rise steeply to a well-defined caldera rim reaching
515 m elevation in the NW and SE. The inner caldera walls are precipitous,
and the caldera is occupied by a large,
cold, fresh-water lake standing at 30 m elevation. The most recent volcanism
took place from vents within the N half
of the caldera, where there are three cinder-cone complexes. The westernmost
cinder-cone complex is densely forested
and rather degraded.During several smaller eruptions in the last ten years,
pumice stones and ash has been spread to
islands within 30-50km.
Looking down into the vertical-walled
Lofia crater to an orange-colored, circular zone of lava on the floor,
March 2009.Courtesy
of X. Rosset./GVN
KAO
Volcano Number: 0403-061
Last Known Eruption: Holocene?
Clouds
almost entirely obscure the small island of Kao (lower-center) in this
NASA Space Shuttle image,
and a circular cloud pattern rises above the caldera rim of the larger
island of Tofua (left-center).
Kao is the highest volcano of the Tonga Islands, rising steeply to 1030
m about 6 km north of Tofua.
No historical eruptions are known from Kao, and fresh-appearing lava
flows are not seen, although the absence
of sufficient time for erosion to produce deep gullies or high sea cliffs
suggests a very recent origin. NASA Space Station image ISS008-E-14026, 2004 (http://eol.jsc.nasa.gov/)/GVN.
An
aerial photo of Late taken July 1990 shows the main summit crater breached
to the SE and a NE graben
occupied by large pit craters, the largest of which contains a saltwater
lake. Except for remnant of a small lava
plug in the summit crater, no fresh lava flows are present.
The small, 6-km-wide circular island of Late rises 1500 m from the sea
floor, with its conical summit reaching
540 m above sea level. Aerial photo by
Tonga Ministry of Lands, Survey, and Natural Resources, 1990 (published
in Taylor and Ewart, 1997).
UNNAMED
Volcano Number: 0403-091
Last Known Eruption: 1854
A submarine volcano along the Tofua volcanic arc was first observed
in September 2001. The newly discovered volcano
lies NW of the island of Vava'u about two-thirds of the way between
Late and Fonualei volcanoes.
The site of the eruption is along a NNE-SSW-trending submarine plateau
south of Fonualei with an approximate
bathymetric depth of 300 m. T-phase waves were recorded on September
27-28, and on the 27th local fishermen
observed an ash-rich eruption column that rose above the sea surface.
No eruptive activity was reported after the 28th,
but water discoloration was documented during the following month. In
early November rafts and strandings of dacitic
pumice were reported along the coast of Kadavu and Viti Levu in the
Fiji Islands. The depth of the summit of the
submarine cone following the eruption determined to be 40 m during a
2007 survey; the crater of the 2001 eruption
was breached to the east.
Map
of the southwest Pacific Ocean showing the location of the unnamed
volcano in the
Tofua volcanic arc that erupted in September-October 2001 producing
the pumice rafts.
The general dispersal trajectory of the sea-rafted pumice is shown
by the dashed line,
and the pumice reached the eastern Australian coastline ~ 1 year
after the eruption. Courtesy of Scott Bryan/GVN.
May 2007: An echo sounding depth survey of a recently active unnamed
volcanic seamount (volcano number 0403-091)
~50 km NW of Vava'u was undertaken on 23 February 2007. The seamount
is located within a roughly N-S segment
of the submerged Tofua volcanic arc on a relatively broad plateau of
less than 1,000 m depth, upon which five other
seamounts rising to depths of 100 m are indicated on current bathymetric
maps.
One seamount indicated to shoal to depths of ~270 m, based on a reported
spot depth recording in 1965,
may correspond to this volcano.
A relatively flat-topped seamount occurs with a maximum length of ~1.2
km (NW-SE) and 0.83 km width (NE-SW)
; much of the summit region is at or above 53 m below sea level.
Seen
from the NE, Fonualei volcano has an upturned saucer profile.
The small, less than 2-km-wide island of Fonualei contains a fumarolically
active crater,
which is breached to the SW with a fresh lava flow extending to the
sea
and forming a rugged shoreline.
Eruptions at Fonualei have been recorded since 1791, with the two largest
taking place in October 1846 and July 1847. Photo by Paul Taylor (published in Taylor and Ewart, 1997)/GVN.
The small island of Fonualei contains a fumarolically active crater,
which is breached to the SW with a fresh lava flow
extending to the sea and forming a rugged shoreline. Steep, inward-facing
scarps mark the rim of a partially exposed
caldera which contains a pyroclastic cone that is breached to the east
and forms the 180-m-high summit of the island.
Blocky lava flows from this cone fill much of the northern caldera moat
and reach the sea through notches in the northern
and eastern caldera rims. In contrast to the andesitic and basaltic
rocks of other islands of the Tonga arc, Fonualei lavas
are of dominantly dacitic composition. Eruptions have been recorded
since 1791, with the largest taking place in June 1846,
when explosive eruptions produced large pumice rafts, and ashfall damaged
crops on the island of Vavua (56 km away)
and fell on vessels up to 950 km distant. In 1939 explosive and effusive
activity occurred from summit and flank vents,
and water spouts were reported 1.6 km SE of the island.
Megapodes alive and well on Fonualei
Ten years after a bold attempt to save the last megapodes of the
Pacific islands, hundreds of the birds have been
found living and breeding. The discovery doubles the number of
malaus, as the megapodes are called in Polynesia,
and could take them off the critically endangered list.
The small, grey, ground-dwelling birds belong to the same family
as pheasants and turkeys. In 1993 only 400
adult malaus remained on the Tongan island of Niuafoou, following
years of illegal egg-eating by islanders and
hunting by introduced cats and dogs. A natural disaster - such
as another eruption of Niuafoou's volcano could
have made the birds extinct. So Dieter Rinke of the German-based
Brehm Fund for International Bird
Conservation shipped 70 eggs and 10 chicks to the island of Fonualei,
200km away.
The malaus' new home had to meet their unique breeding requirements:
they bury their eggs in volcanic ash to be
incubated by its warmth. Cats and snakes cannot be present,
as they devour the buried eggs and chicks.
Fonualei is uninhabited and volcanic, yet many experts remained
sceptical that the malaus would survive.
They thought it wouldn't support megapodes because the difference
in habitats was too great.
Scientists found the new population of birds when he visited
the island in March this year.
It is estimated that 300-500 adults now live on Fonualei. The Guardian, Thursday 24
July 2003 02.17 BST
Tongan Megapode. Family: Megapodiidae
The Tongan Megapode, Megapodius pritchardii, is a species
of bird in the megapode family Megapodiidae,
currently endemic to Tonga. The species is also known as the
Polynesian Megapode, and as the Niuafo'ou
Megapode after the island of Niuafo'ou to which it was restricted
for many years.
The Tongan Megapode is the only remaining species of megapode
in Tonga out of the four or five species that
were present on the islands in prehuman times , and indeed the
only species of megapode that survives in Polynesia. . The species
itself once had a more widespread distribution, occurring across
most of Tonga, Samoa and Niue.
The cause of all these extinctions and declines was the arrival
of humans on the islands, and the associated predation
on adults and particularly eggs, as well as predation by introduced
species. On Niuafo'ou the small human
population and remoteness of its habitat probably saved the
species.
Its natural habitat is tropical moist lowland forests. On Niuafo'ou
it is most common on the central caldera.
The Tongan Megapode, like all megapodes, does not incubate its
eggs by sitting on them; instead the species buries
them in warm volcanic sands and soil and allows them to develop.
On islands in former parts of its range without
volcanoes it presumably created mounds of rotting vegetation
and laid the eggs there. The young birds are capable
of flying immediately after hatching.
Today the Tongan Megapode is principally threatened by the
same factors that caused its decline in the rest of
Polynesia. Its eggs are still harvested by local people in spite
of theoretical government protection, and some
hunting still occurs. The species is apparently afforded some
protection by the difficulty in reaching its habitat.
Because of the vulnerability of the single population an attempt
was made to translocate eggs of this species
to new islands, Late and Fonualei. The translocation
was successful on Fonualei and an estimated 350–500
birds
now breed there, but surveys of Late subsequently found that
the translocation there had failed. From Wikipedia, the
free encyclopedia:
TAFAHI
Volcano Number: 0403-101
Last Known Eruption: Unknown
Conical
Tafahi, the northernmost subaerial volcano of the Tofua volcanic arc. Photo by Paul Taylor (published
in Taylor and Ewart, 1997).
The small 1.2 x 2.8 km wide island of Tafahi is a conical stratovolcano
that rises to 560 m about 7 km north of the island of
Niuatoputapu in the northern Tonga Islands. Tafahi is the northernmost
subaerial volcano of the Tofua volcanic arc. The basaltic-andesite volcano
is elongated in a N-S direction, and the summit is located at the SW
side of the island.
The western side of the volcano is the most dissected, and a narrow
fringing reef partially encircles the island.
No historical eruptions have been reported from Tafahi, but its youthful
morphology, which resembles that of the larger
Kao volcano in the Central Tonga Islands, suggests recent activity.
We
walked through the only village and noticed how rich the soil
appears.
Food seems to be growing everywhere. The children picked fresh
mangos for us as we
walked, and they were delicious. We had the opportunity to talk
with a few residents
whom speak some English, and they were a delight – so friendly
and welcoming.
We saw some rather spectacular ocean views as we roamed part way
up the hill,
then we stopped at a particularly charming house to eat, drink,
and rest. Bud & Nita on
SV Passaage, http://www.svpassage.com/Tafahi.htm
CURACOA
Volcano Number: 0403-102
Last Known Eruption: 1979
A
raft of floating pumice from a July 1973 submarine eruption closes behind
the wake of a ship.
This was the first report of an eruption from the Curacoa submarine
volcano in the northern Tonga Islands.
The pumice raft covered an area of more than 100 sq km and was encountered
by a ship 200 km to the west
nearly two weeks after the start of the eruption. Another eruption was
observed in the same general area in 1979. Photo by the crew
of the vessel "Port Nicholson," 1973 (courtesy of Tom Simkin,
Smithsonian Institution).
A submarine volcano south of Curacoa Reef at the northern end of
the Tofua vol.arc was first observed in eruption in 1973.
Explosive eruptions, which produced large rafts of dacitic pumice covering
an area of more than 100 sq km, were observed
from the island of Tafahi, 27 km to the SSW. The eruption site was located
about 6.5 km SW of Curacoa Reef.
Multiple submarine vents are apparently located in this area; a second
eruption was reported in 1979 from a location
13 km north of Tafahi.
Niuafo'ou
caldera is seen from its eastern rim, displaying both caldera lakes,
the large Vai Lahi (background)
and the much smaller Vai Si'i (foreground). Niuafo'ou ("Tin Can
Island") is a low, 8-km-wide island that forms the
summit of a largely submerged shield volcano. The 5-km-wide caldera
is mostly filled by Vai Lahi, whose lake
bottom extends to below sea level. Historical eruptions, mostly from
circumferential fissures, have been recorded
since 1814 and have often damaged villages on this small ring-shaped
island. Photo by Paul Taylor (published
in Taylor and Ewart, 1997)/GVN.
Niuafo'ou is Tonga's most active volcano with at least 10 periods of
activity, both explosive and effusive, since the early
1800s. The most recent period of activity in 1946 (Taylor 1999) resulted
in the complete evacuation of the island.
This volcanic center, ~450 km N of Tongatapu, is an isolated volcanic
island located in the N-central Lau Basin.
In May 1999 a vent was producing hot water and H2S, and dead fish were
observed near the vent .
October 2002 fumarolic activity were reported in two areas of the central
caldera.
On 20 October fumarolic and hot spring activity was noted in the NE
part of the caldera.
Traditional
Island-dresses on Niuafo'ou From http://matthew.mumford.com/Polynesia-Expedition-Log-3.htm
Young
curtain lava flow draped and folded over the landscape originated from
the Puipui eruption of Maka
volcano along the NE Lau Spreading Center, as photographed during a
2009 NOAA Vents Program expedition.
A 2008 expedition to the Lau Basin documented submarine hydrothermal
plumes from Maka volcano on
November 21. The chemistry of water samples suggested that these fluids
could be warmed by a very recent
(days or weeks?) eruption of lava onto the seafloor. A return visit
in May 2009 showed fresh lava flows,
but without gas emission. Courtesy of NSF and NOAA
Ocean Exploration Program, 2009.
A
bathymetric map prepared during a NOAA Vents Program November 2008 expedition
shows
two submarine volcanoes, Tafu (Tongan for "source of fire")
and Maka (Tongan for "rock").
The volcanoes lie along a NE-SW-trending ridge on the southern part
of the back-arc NE Lau Spreading Center. Courtesy of NOAA Vents
Program, 2008.
Two submarine volcanoes, Tafu and Maka, lie along a NE-SW-trending ridge
segment on the southern part of the
NE Lau Spreading Center (NELSC). The NELSC is a back-arc spreading center
in the northeast part of the Lau Basin.
Tafu rises to about 1400 m below sea level at the NE end of the ridge
segment, and Maka reaches 1560 m below sea level
at the SW end of the ridge segment. A November 2008 NOAA Vents Program
expedition discovered submarine
hydrothermal plumes consistent with very recent (days to weeks?) submarine
lava effusion from Maka volcano.
A return visit in May 2009 documented the freshly emplaced lava flow at
Maka.
Incandescence
and a plume rise above the Hades vent of West Mata,
a submarine volcano rising to within 1174 m of the sea surface, in May
2009. Courtesy of NSF and NOAA
Ocean Exploration Program, 2009.
West
Mata, a submarine volcano rising to within 1174 m of the sea surface,
is located in the northeastern Lau Basin
at the northern end of the Tonga arc, about 200 km SW of Samoa. West Mata
volcano lies about 7 km west of another
submarine volcano, East Mata; both lie at the northern end of the Tonga
arc, north of the historically active Curacoa
submarine volcano. The two volcanoes were discovered during a November
2008 NOAA Vents Program expedition, and
West Mata was found to be producing submarine hydrothermal plumes consistent
with a recent or lava effusion.
A return visit in May 2009 documented explosive and effusive activity
from two closely spaced vents, one at the summit,
and the other on the SW rift zone.
An eruption plumes rises from the Prometheus vent at Maka submarine
volcano in May 2009.
A November 2008 NOAA Vents Program expedition to the Lau Basin
had discovered
hydrothermal plumes from an actively erupting site on the summit
of West Mata volcano.
During a return trip in May 2009 explosive and effusive activity
was observed from Hades,
a vent on the SW flank, and explosive activity ejecting ash
and bombs was seen from a
cinder cone at the Prometheus vent at the summit. Courtesy of NSF
and NOAA Ocean Exploration Program, 2009.
It was scene of inferred ongoing eruptions when the volcano was visited
during November 2008 and an unambiguous
eruption at multiple vents when visited during May 2009. West Mata is
located in the NE Lau basin ~ 35 km E of the
closest portion of the Lau spreading center and ~ 70 km NE of a now-erupting
portion of the NE Lau spreading center
(NELSC). Investigations of this site were made on two research cruises
conducted in the region by the Research Vessel
(R/V) Thompson during November 2008 and May 2009.
Photograph
of lava sample collected at West Mata. Courtesy of K. Rubin /GVN.
Among
the many attributes of this event was the unique style of eruption from
multiple active vents. In addition, the lavas
were composed of boninite (a lava of olivine-bronzite andesite composition
containing little or no feldspar), making this the
first observed eruption of a lava of this composition. Such lavas have
previously been seen only on volcanoes over a million
years old, and are thought to represent the early stages of subduction
in primitive island arcs. One of the tasks on the cruise
was to sample an active lava pillow. (Time difference between what
was found - and what it should have been -
reminds of Surtsey back in 1963).
Oceanographers
using the remotely operated vehicle (ROV) Jason discovered and
recorded
the first video and still images of a deep-sea volcano actively
erupting molten lava on the seafloor.
Jason, designed and operated by the Woods Hole Oceanographic Institution
for the National Deep
Submergence Facility, utilized a prototype, high-definition still
and video camera to capture the
powerful event nearly 1.200m below the surface of the Pacific
Ocean, in an area bounded by
Fiji, Tonga and Samoa. Uploaded to Youtube.com by WoodsHoleOceanInst
17. des. 2009
(Courtesy National Science Foundation and , National OOceanic
and Atmospheric Administration, AIVL/WHOI)
Most
of the information given here on the volcanoes of Tonga, are collected
from http://www.volcano.si.edu
Just
couldn't help it - had to include this one From a postcard: "Greetings from the Kingdom of Tonga!
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