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Surtsey
Surtsey's ash column rises over the newly forming island
Vesstmannaerjar, Iceland
Earth's Natural Wonders in Europe & Middle East
Elevation of island: 570 feet (174 m)
Diameter of island: 0.93 miles (1.5 km)
Area of island: 1.08 square miles (2.8 sq. km.)
 
Surtsey Eruption[1]

 

The eruption vents in 1999
In November 1963, fishermen setting their nets about 20 miles south of Iceland's main island noticed things were not as they should be. Not long afterward a volcano erupted from the seabed, gentle at first, but more explosive as it reached the surface, with volcanic bombs and dust ejecting above the vent. It was not alone. Three other vents were active at the same time: Syrtlingur and Jolnin each formed an island that was later worn away by the sea, while Surtla never pushed above the surface. Surtsey, however remained, and was named after Surtur, a giant of fire in Norse mythology [3]
The eruption vents in 1999 [2]

 

Surtsey (Icelandic: "Surtur's island") is a volcanic island off the southern coast of Iceland. It is also the southernmost point of Iceland. It was formed in a volcanic eruption which began 130 metres (426 ft) 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 (1.0 sq mi). Since then, wind and wave erosion have caused the island to steadily diminish in size: as of 2002, its surface area was 1.4 km2 (0.54 sq mi).

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 biologists as life forms 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 Jólnir and other, unnamed peaks. Most of these eroded away fairly quickly.

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 thought it might have been 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. From 6 to 8 November, weak tremors were detected at Kirkjubaejarklaustur from an epicentre measured to be 140 km (87 mi) distant (approximately the distance of Surtsey), while on 12 November, a seismograph in Reykjavík recorded weak tremors for ten hours, but their location was not determined.[3] Two days before the eruption began, a marine research vessel noted that the sea in the area was somewhat warmer than normal,[4] and at the same time, people in the coastal town of Vík on the mainland 80 km (50 mi) 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 (426 ft) 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 contained, and activity broke the surface.

Early days

Surtsey's ash column rises over the newly forming islandBy 11:00 on 14 November 1963, the eruption column had reached several kilometers 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 (1640 ft) in length and had reached a height of 45 metres (147 ft).[5]

The new island was named after the fire jötunn Surtr 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 (2950 by 2130 ft). 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 (4265 ft).

One notable 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.


Permanent island
The explosive phreatomagmatic eruptions caused by the easy access of water to the erupting vents threw rocks up to a kilometer (0.6 mi) away from the island, and sent ash clouds as high as 10 km (6 mi) 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 (0.97 sq mi).

On 28 December 1963 submarine activity 2.5 km (1.5 mi) to the north-east of Surtsey caused the formation of a ridge 100 m (328 ft) 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 (75 ft) to 47 m (154 ft) below sea level.


Eruption gradually dies down

The eruption vents in 1999In 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 (0.37 mi) off the northern shore. By 28 May an island had appeared, and was named Syrtlingur (Little Surtsey). 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 (0.058 sq mi). 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 (0.56 mi) south-west 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 (230 ft) in height, covering an area of 0.3 km2 (0.12 sq mi), 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 (0.24 cu mi), and the island's highest point was 174 metres (570 ft) 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 (0.0058 cu mi) of material has been lost due to erosion – this represents about a quarter of the original above-sea-level volume of the island.[1]

 

You Tube Video

Beginning in November 1963, a violent eruption of ash and lava from the seafloor off the coast of Iceland forms a new volcanic island, Surtsey.

 

BritannicaOnline
February 07, 2007

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References
 
1- Wikipedia- Surtsey-retrieved 7/18/2009
2. Wikimedia Commons-Surtsey Eruption-retrieved 7/18/2009
3. Wikimedia Commons- Surtsey Craters-retrieved 7/18/2009
4. 1,001 Natural Wonders You Must See Before You Die 2005-p. 281- Michael Bright-retrieved 6/22/2009
 
 
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