Surtsey is a volcanic island located in the Vestmannaeyjar archipelago off the
southern coast of Iceland. At 63.303°N 20.605°W﻿ / 63.303; -20.605, Surtsey is
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 lasted until 5 June 1967, when the island reached its maximum size
of 2.7 km2. Since then, wave erosion has caused the island to steadily diminish
in size: as of 2002, its surface area was 1.4 km2. The most recent survey
shows the island's maximum elevation at 155 m above sea level.
The new island was named after Surtr, a fire jötunn or giant from Norse
mythology. It was intensively studied by volcanologists during its eruption, and
afterwards by botanists and other biologists as life forms gradually
colonised the originally barren island. The undersea vents that produced Surtsey
are part of the Vestmannaeyjar 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 Jólnir and unnamed other peaks. Most of these eroded away fairly
quickly. Geology
= Formation = The eruption was unexpected, and almost
certainly began some days before it became apparent at the surface. The sea
floor at the eruption site is 130 metres below sea level, and at this depth
volcanic emissions and explosions would be suppressed, quenched and dissipated
by the water pressure and density. Gradually, as repeated flows built up a
mound of material that approached sea level, the explosions could no longer be
contained, and activity broke the surface.
The first noticeable indications of volcanic activity were recorded at the
seismic station in Kirkjubæjarklaustur, Iceland from 6 to 8 November, which
detected weak tremors emanating from an epicentre approximately west-south-west
at a distance of 140 km, the location of Surtsey. Another station in Reykjavík
recorded even weaker tremors for ten hours on 12 November at an undetermined
location, when seismic activity ceased until 21 November. That same day, people
in the coastal town of Vík 80 km away noticed a smell of hydrogen sulphide. On
13 November, a fishing vessel in search of herring, equipped with sensitive
thermometers, noted sea temperatures 3.2 km SW of the eruption center were 2.4°C
higher than surrounding waters. Eruption at the surface
At 07:15 UTC on 14 November 1963, the cook of Ísleifur II, a trawler sailing
these same waters spotted a rising column of dark smoke southwest of the
boat. The captain thought it might have been a boat on fire, and ordered the
vessel to investigate. Instead, they encountered explosive eruptions giving
off black columns of ash, indicating that a volcanic eruption had begun to
penetrate the surface of the sea. By 11:00 the same day, the eruption column
had reached several kilometres in height. At first the eruptions took
place at three separate vents along a northeast by southwest 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.
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, 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. 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. The new island was named after the fire
jötunn Surtur from Norse mythology. Three French journalists representing
the magazine Paris Match notably landed there on 6 December 1963, staying 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.
Permanent island 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 from
being washed away rapidly. Effusive eruptions continued until 1965, by which
time the island had a surface area of 2.5 km2.
On 28 December 1963 submarine activity 2.5 km to the north-east of Surtsey
caused the formation of 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. Subsequent volcanic activity
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. The new island was washed
away during early June, but reappeared on 14 June. Eruptions at Syrtlingur were
much smaller in scale than those that had built Surtsey, with the average rate
of emission of volcanic materials being about a tenth of the rate at the main
vent. Activity was short-lived, continuing until the beginning of
October 1965, by which time the islet had an area of 0.15 km2. Once the
eruptions had ceased, wave erosion rapidly wore the island away, and it
disappeared beneath the waves on 24 October.
During December 1965, more submarine activity occurred 0.9 km southwest of
Surtsey, and another island was formed. It was named Jólnir, and over the
following eight months it appeared and disappeared several times, as wave
erosion and volcanic activity alternated in dominance. Activity at Jólnir was
much weaker than the activity at the main vent, and even weaker than that
seen at Syrtlingur, but the island eventually grew to a maximum size of 70
m in height, covering an area of 0.3 km2, during July and early August 1966.
Like Syrtlingur, though, after activity ceased on 8 August 1966, it was rapidly
eroded, and dropped below sea level during October 1966.
Effusive eruptions on the main island returned on 19 August 1966, with fresh
lava flows 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 at that time.
Since the end of the eruption, erosion has seen the island diminish in size. A
large area on the southeast side has been eroded away completely, while a
sand spit called Norðurtangi 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. Its maximum elevation has diminished to 155 m.
= Recent development = 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 one 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 1.0 hectare of its surface area each year.
= Future = This island is unlikely to disappear
entirely in the near future. The eroded area consisted mostly of loose tephra,
easily washed away. 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. Estimates of how long Surtsey will
survive are based on the rate of erosion seen up to the present day. Assuming
that the current rate does not change, the island will be mostly at or below
sea level by 2100. However, the rate of erosion is likely to slow as the tougher
core of the island is exposed: an assessment assuming that the rate of
erosion will slow exponentially suggests that the island will survive for many
centuries. 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. Biology
= Settlement of life = A classic site for the study of
biocolonisation from founder populations that arrive from outside, Surtsey was
declared a nature reserve in 1965 while the eruption was still in active
progress. Today only a few scientists are permitted to land on Surtsey; the
only way anyone else can see it closely is from a small plane. This allows the
natural ecological succession for the island to proceed without outside
interference. In 2008, UNESCO declared the island a World Heritage Site, in
recognition of its great scientific value.
Plant life In the spring of 1965 the first vascular
plant was found growing on the northern shore of Surtsey, mosses became visible
in 1967 and lichens were first found on the Surtsey lava in 1970. Plant
colonisation on Surtsey has been closely studied, the vascular plants in
particular as they have been of far greater significance than mosses,
lichens and fungi in the development of vegetation.
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 vascular plant
species were able to survive. In 1998, the first bush was found on the island—a
tea-leaved willow, which can grow to heights of up to 4 metres. By 2008, 69
species of plant had been found on Surtsey, of which about 30 had become
established. This compares to the approximately 490 species found on
mainland Iceland. More species continue to arrive, at a typical rate of roughly
2–5 new species per year. Birds
The expansion of bird life on the island has both relied on and helped to advance
the spread of plant life. Birds use the plants for nesting material, but also
continue to assist in the spreading of seeds, and fertilize the soil with their
guano. Birds first began nesting on Surtsey three years after the eruptions
ended, with fulmar and guillemot the first species to set up home. Twelve
species are now regularly found on the island.
A gull colony has been present since 1984, 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 nesting Atlantic puffins, which 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 Europe and Iceland.
Species that have been seen briefly on the island include whooper swans,
various species of geese, and common ravens. Although Surtsey lies to the
west of the main migration routes to Iceland, it has become a more common
stopping point as its vegetation has improved. In 2008, the 14th bird species
was detected with the discovery of a common raven's nest.
According to a 30 May 2009 report, a golden plover was nesting on the island
with four eggs. 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 harbour seals, but both are now well established. The
presence of seals attracts orcas, 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
carcasses 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. However, the next year earthworms were not found.
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.
Human impact The only other significant human impact
is a small prefabricated hut which is used by researchers while staying on the
island. The hut includes a few bunk beds and a solar power source to drive an
emergency radio and other key electronics. All visitors check
themselves and belongings to ensure no seeds are accidentally introduced by
humans to this ecosystem. It is believed that some young boys tried to introduce
potatoes, which were promptly dug up once discovered. An improperly handled
human defecation resulted in a tomato plant taking root which was also
destroyed. In 2009 a weather station for weather observations and a webcam were
installed on Surtsey. See also
Geography of Iceland Iceland plume
List of islands of Iceland List of new islands
List of volcanoes in Iceland Volcanology of Iceland
References External links
Website of The Surtsey Research Society Weather observations on Surtsey
Webcam on Surtsey Aerial photos, maps and volcanic geology
of Surtsey. Visit Westman Islands
Surtsey Topography The Surtsey Research Society, which
administers the island A notice from the Environmental & Food
Agency declaring Surtsey a protected area
Explore North site illustrates postage stamps.
Extensive information about plant and bird life on the island