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Surtsey

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   Surtsey, sixteen days after the onset of the eruption
   Enlarge
   Surtsey, sixteen days after the onset of the eruption

   Surtsey ( Icelandic: " Surtur's island") is a volcanic island off the
   southern coast of Iceland. At 63.30° N 20.62° W it is also the
   southernmost point of Iceland. It was formed in a volcanic eruption
   which began 130 metres below sea level, and reached the surface on 14
   November 1963. The eruption may have started a few days earlier and
   lasted until 5 June 1967, when the island reached its maximum size of
   2.7 km². Since then, wind and wave erosion has seen the island steadily
   diminish in size: as of 2005 it is only 1.4 km² in size.

   The new island was named after the fire giant Surtur from Norse
   mythology, and was intensively studied by volcanologists during its
   creation and, since the end of the eruption, has been of great interest
   to botanists and biologists as life has gradually colonised the
   originally barren island. The undersea vents that produced Surtsey are
   part of the Vestmannaeyjar (Westmann Isles) submarine volcanic system,
   part of the fissure of the sea floor called the Mid-Atlantic Ridge.
   Vestmannaeyjar also produced the famous eruption of Eldfell on the
   island of Heimaey in 1973. The eruption that created Surtsey also
   created a few other small islands along this volcanic chain, such as
   Jolnir and other unnamed peaks. Most of these eroded away fairly
   quickly.

Precursors to the eruption

   Surtsey in southwest Iceland
   Enlarge
   Surtsey in southwest Iceland

   At 07:15 UTC+0 on 14 November 1963, the cook of Ísleifur II, a trawler
   sailing off the Vestmannaeyjar archipelago south of Iceland, spotted
   something south-west of the boat, which turned out to be a rising
   column of dark smoke. The vessel went to investigate the smoke, the
   captain thinking it might be a boat on fire, but instead they
   encountered explosive eruptions giving off black columns of ash,
   indicating that a volcanic eruption had begun beneath the sea.

   Although the eruption was unexpected, there had been some indications
   before it began that volcanic activity was imminent. A week beforehand,
   a seismograph in Reykjavík recorded weak tremors, but their location
   was not determined. Two days before the eruption began, a marine
   research vessel noted that the sea in the area was somewhat warmer than
   normal, and at the same time, people in the coastal town of Vík on the
   mainland 80 km away had noticed a smell of hydrogen sulphide.

   It is likely that the eruption had begun some days before 14 November.
   The sea floor is 130 metres below sea level, and at this depth
   explosive eruptions would be quenched by the water pressure. As the
   eruption built up a volcano approaching sea level, the explosions could
   no longer be quenched, and the eruption broke the surface.

Early days

   Surtsey's ash column rises over the newly forming island
   Enlarge
   Surtsey's ash column rises over the newly forming island

   By 11:00 on 14 November 1963, the eruption column had reached several
   kilometres in height. At first the eruptions took place at three
   separate vents along a north-east by south-west trending fissure, but
   by the afternoon the separate eruption columns had merged into one
   along the erupting fissure. Over the next week, explosions were
   continuous, and after just a few days the new island, formed mainly of
   scoria, measured over 500 metres in length and had reached a height of
   45 metres. The new island was named after the fire giant Surtur from
   Norse mythology. As the eruptions continued, they became concentrated
   at one vent along the fissure and began to build the island into a more
   circular shape. By 24 November, the island measured about 900 metres by
   650 metres. The violent explosions caused by the meeting of lava and
   sea water meant that the island consisted of a loose pile of volcanic
   rock ( scoria), which was eroded rapidly by north Atlantic storms
   during the winter. However, eruptions more than kept pace with wave
   erosion, and by February 1964, the island had a maximum diameter of
   over 1300 metres.

   One interesting event early in the island's life was the landing of
   three French journalists representing the magazine Paris Match on 6
   December 1963. They stayed for about 15 minutes before violent
   explosions encouraged them to leave. The journalists jokingly claimed
   French sovereignty over the island, but Iceland quickly asserted that
   the new island belonged to it, having appeared in Icelandic territorial
   waters. Ferdinandea, near Sicily, is another island created by volcanic
   eruptions which has been subject to disputes over sovereignty.

A permanent island

   Surtsey as seen from above
   Enlarge
   Surtsey as seen from above

   The explosive phreatomagmatic eruptions caused by the easy access of
   water to the erupting vents threw rocks up to a kilometre away from the
   island, and sent ash clouds as high as 10 km up into the atmosphere.
   The loose pile of unconsolidated tephra would quickly have been washed
   away had the supply of fresh magma dwindled, and large clouds of dust
   were often seen blowing away from the island during this stage of the
   eruption.

   By early 1964, though, the continuing eruptions had built the island to
   such a size that sea water could no longer easily reach the vents, and
   the volcanic activity became much less explosive. Instead, lava
   fountains and flows became the main form of activity. These resulted in
   a hard cap of extremely erosion-resistant rock being laid down on top
   of much of the loose volcanic pile, which prevented the island being
   washed away rapidly. Effusive eruptions continued until 1965, by which
   time the island had a surface area of 2.5 km².

   28 December 1963 saw the onset of submarine activity 2.5 km to the
   north-east of Surtsey, which formed a ridge 100 m high on the sea
   floor. This seamount was named Surtla, but never reached sea level.
   Eruptions at Surtla ended on 6 January 1964, and it has since been
   eroded from its minimum depth of 23 m to 47 m below sea level.

The eruption gradually dies down

   The eruption vents today
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   The eruption vents today

   In 1965 the activity on the main island diminished, but at the end of
   May that year an eruption began at a vent 0.6 km off the northern
   shore. By 28 May an island had appeared, and was named Syrtlingur.
   Eruptions at Syrtlingur continued until the beginning of October 1965,
   by which time the islet had an area of 0.15 km², but it was rapidly
   eroded away once the eruptions had ceased, disappearing beneath the
   waves on 24 October.

   During December 1965, more submarine activity occurred 0.9 km
   south-west of Surtsey, and another island was formed. It was named
   Jólnir, and over the following eight months it grew to 70 m in height,
   covering 0.3 km². Like Syrtlingur, though, after activity ceased on 8
   August 1966, it was rapidly eroded, and dropped below sea level during
   October 1966.

   19 August 1966 saw the return of effusive eruptions on the main island,
   giving it further resistance to erosion. The eruption rate diminished
   steadily though, and on 5 June 1967, the eruption ended. The volcano
   has been dormant ever since. The total volume of lava emitted during
   the three-and-a-half-year eruption was about one cubic kilometre, and
   the island's highest point was 174 metres above sea level.

   Since the end of the eruption, erosion has seen the island diminish in
   size. A large area on the south-east side has been eroded away
   completely, while a sand spit called Norðurtangi (north point) has
   grown on the north side of the island. It is estimated that about 0.024
   km³ of material has been lost due to erosion – this represents about a
   quarter of the original above sea level volume of the island.

The settlement of life

   A classic site for the study of biocolonisation from founder
   populations that arrive from outside ('allochthonous'), Surtsey was
   declared a nature reserve in 1965 while the eruption was still in
   active progress. Today only a small number of scientists are permitted
   to land on Surtsey; the only way anyone else can see it closely is with
   a small plane.

Plant life

   Life settled slowly on the island. The first life to appear was moss
   and lichen, which began to appear on the island as early as 1965.
   Mosses and lichens now cover much of the island. During the island's
   first 20 years, 20 species of plants were observed at one time or
   another, but only 10 became established in the nutrient-poor sandy
   soil.

   As birds began nesting on the island, soil conditions improved, and
   more advanced species of plants were able to survive. In 1998, the
   first bush was found on the island – a Salix phylicifolia bush, which
   can grow to heights of up to 4 metres. In total at least 60 species of
   plant have been found on Surtsey, of which about 30 have become
   established. More species continue to arrive, at a typical rate of
   roughly 2–5 new species per year.

Birds

   The first puffin nests were found on Surtsey in 2004
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   The first puffin nests were found on Surtsey in 2004

   The expansion of bird life on the island has both relied on and helped
   to advance the spread of plant life. Birds use plants for nesting
   material, but also assist in the spreading of seeds, and fertilise the
   soil with their guano. Birds began nesting on Surtsey three years after
   the eruptions ended, with fulmar and guillemot the first species to set
   up home. Eight species are now regularly found on the island.

   A gull colony has been present since 1986, although gulls were seen
   briefly on the shores of the new island only weeks after it first
   appeared. The gull colony has been particularly important in developing
   the plant life on Surtsey, and the gulls have had much more of an
   impact on plant colonisation than other breeding species due to their
   abundance. An expedition in 2004 found the first evidence of Atlantic
   Puffins nesting on the island. Puffins are extremely common in the rest
   of the archipelago.

   As well as providing a home for some species of birds, Surtsey has also
   been used as a stopping-off point for migrating birds, particularly
   those en route between the British Isles and Iceland. Species that have
   been seen briefly on the island include whooper swans, various species
   of goose, and ravens. Although Surtsey lies to the east of the main
   migration routes to Iceland, it has become a more common stopping point
   as its vegetation has improved.

Marine life

   Soon after the island's formation, seals were seen around the island.
   They soon began basking there, particularly on the northern spit, which
   grew as the waves eroded the island. Seals were found to be breeding on
   the island in 1983, and a group of up to 70 made the island their
   breeding spot. Grey seals are more common on the island than common
   seals, but both are now well established. The presence of seals
   attracts killer whales, which are frequently seen in the waters around
   the Vestmannaeyjar archipelago and now frequent the waters around
   Surtsey.

   On the submarine portion of the island, many marine species are found.
   Starfish are abundant, as are sea urchins and limpets. The rocks are
   covered in algae, and seaweed covers much of the submarine slopes of
   the volcano, with its densest cover between 10 and 20 metres below sea
   level.

Other life

   Insects arrived on Surtsey soon after its formation, and were first
   detected in 1964. The original arrivals were flying insects, carried to
   the island by winds and their own power. Some were believed to have
   been blown across from as far away as mainland Europe. Later insect
   life arrived on floating driftwood, and both live animals and corpses
   washed up on the island. When a large, grass-covered tussock was washed
   ashore in 1974, scientists took half of it for analysis and discovered
   663 land invertebrates, mostly mites and springtails, the great
   majority of which had survived the crossing .

   The establishment of insect life provided some food for birds, and
   birds in turn helped many species to become established on the island.
   The bodies of dead birds provide sustenance for carnivorous insects,
   while the fertilisation of the soil and resulting promotion of plant
   life provides a viable habitat for herbivorous insects.

   Some higher forms of land life are now colonising the soil of Surtsey.
   The first earthworm was found in a soil sample in 1993, probably
   carried over from Heimaey by a bird. Slugs were found in 1998, and
   appeared to be similar to varieties found in the southern Icelandic
   mainland. Spiders and beetles have also become established.

The future of Surtsey

   The island of Surtsey in 1999
   Enlarge
   The island of Surtsey in 1999

   Following the end of the eruption, scientists established a grid of
   benchmarks against which they measured the change in the shape of the
   island. In the 20 years following the end of the eruption, measurements
   revealed that the island was steadily slumping vertically and had lost
   about a metre in height. The rate of slumping was initially about 20 cm
   per year but slowed to 1–2 cm a year by the 1990s. It had several
   causes: settling of the loose tephra forming the bulk of the volcano,
   compaction of sea floor sediments underlying the island, and downward
   warping of the lithosphere due to the weight of the volcano.

   The typical pattern of volcanism in the Vestmannaeyjar archipelago is
   for each eruption site to see just a single eruption, and so the island
   is unlikely to be enlarged in the future by further eruptions. The
   heavy seas around the island have been eroding it ever since the island
   appeared, and since the end of the eruption almost half its original
   area has been lost. The island currently loses about 10,000 square
   metres of its surface area each year.
   Other islands in the archipelago show the effects of centuries of
   erosion
   Enlarge
   Other islands in the archipelago show the effects of centuries of
   erosion

   However, the island is unlikely to disappear entirely in the near
   future. The eroded area consisted mostly of loose tephra, easily washed
   away by wind and waves. Most of the remaining area is capped by hard
   lava flows, which are much more resistant to erosion. In addition,
   complex chemical reactions within the loose tephra within the island
   have gradually formed highly erosion resistant tuff material, in a
   process known as palagonitization. On Surtsey this process has happened
   quite rapidly, due to high temperatures not far below the surface.

   While the island will undoubtedly get smaller yet, it will nonetheless
   probably persist for many centuries before being eroded away
   completely. An idea of what it will look like in the future is given by
   the other small islands in the Vestmannaeyjar archipelago, which formed
   in the same way as Surtsey several thousand years ago, and have eroded
   away substantially since they were formed. The Icelandic government
   recently announced its wishes for the island to be listed as a UNESCO
   World Heritage Site.
   Retrieved from " http://en.wikipedia.org/wiki/Surtsey"
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