Surtsey: Evolution of an Island

For the past half-century, the Icelandic island of Surtsey has been the ultimate laboratory.  Not only were scientists able to watch the live birth of a volcanic island as it emerged newborn from the ocean floor in late 1963, but they have been able to observe the development of the island as plant and animal life have slowly colonised the formerly barren landscape with minimal human interference.

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Iceland, as many of you are aware, is one of the most volcanically-active places on the planet; the largest piece of land produced by the constant spreading of the seafloor away from the Mid-Atlantic Ridge.  Just off Iceland’s southwest coast lies the Vestmannaeyjar  archipelago, a group of small volcanic islands formed over the past 10-20 000 years.  Approximately 80 separate craters have formed in the chain, of which 17 or 18 have broken above sea level.  On 15 November 1963, the cook of a fishing trawler sailing near the south end of the Vestmannaeyjar noticed a column of dark smoke in the distance.  Believing it to be a nearby ship on fire, the trawler’s captain headed for the smoke column only to discover that the smoke was from a submarine volcanic eruption breaking through the ocean surface.  The lava from the eruption slowly built up a volcano, and by the end of the week, the volcano had not only broken through the surface but built itself into a loosely-consolidated scoria island 500 m (1 640 ft) in length and 45 m (147 ft) in height.

The porous scoria was easily eroded by the action of sea waves, but by the beginning of 1964 the island grew high enough that sea waves could no longer infiltrate the lava vents.  This allowed a harder cap of lava flows to cover the centre of the island; having no contact with water as it emerged and cooled, the new rock being formed was far less porous and thus far more resistant to erosion.  Named for Surtur, a Norse mythological figure associated with fire, the eruption would continue intermittently until 5 June 1967, and Surtsey would reach a maximum size of 2.7 km² (1.04 sq mi).

Surtsey in relation to Reykjavik.

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Source: Pinpin, http://commons.wikimedia.org/wiki/File:Topographic_map_of_Surtsey-fr.svg.  Licensed under the Creative Commons Attribution-Share Alike 3.0 Unported licence.

Today, Surtsey is less than 1.4 km² (0.54 sq mi) in size, and the highest point remains 155 m (508 ft) above sea level.  With no volcanic activity feeding its growth, Surtsey is being eroded at the rate of 1 ha (3 acres) per year, although the rate is slowing as the waves encounter the harder layers of rock formed from the later lava flows, as well as the hardened palagonite tuff core of the island that has settled, consolidated, and been chemically altered.  The most telling evidence of erosion other than the sheer decrease in size is the sand spit that has formed on the north shore of the island, consisting of materials eroded away from the south shore that have been carried northward and deposited by wave action.  Eventually, the tuff core that comprises about one-third of the island will be all that’s left (likely within the next 160 years), but based upon the structures of the other Vestmannaeyjar islands the core should remain intact and above water for several thousands of years, producing a small island surrounded by steep cliffs.  Compare this to other recently-active new volcanic islands such as Tonga’s Home Reef and Solomon Islands’ Kavachi, which have emerged from the ocean periodically over the years only to be washed away within a year or two due to the lack of a hard lava cap.


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Surtsey in winter with the north spit, Norðurtangi, in the foreground.  Note the two separate craters on the island and the vegetated patch at the south end.

Even as the eruption was taking place, the scientific opportunities possible on Surtsey were readily apparent.  The budding island was declared a nature reserve by the Icelandic government in 1965, and all non-scientific travel to the island was banned (scientific operations are conducted from a solitary solar-powered hut).  This would be a chance for the world to see just how quickly nature would find its way to a brand-new, untouched island.  The answer would come that same year in the form of a searocketfound growing near the shoreline, growing from a seed likely carried over the ocean from the island of Heimaey, 18 km (11 mi) away, or the Icelandic coast 32 km (20 mi) away.  Other seeds from grasses, plants, and ferns would come via winds blowing south from the mainland, or from the droppings of birds that stopped on the island.

Vegetative colonisation took off on Surtsey once birds began to form active colonies on the island rather than simply using it as a migratory stop.  It is believed that birds and their droppings are responsible for 75% of all seed dispersal on Surtsey (as opposed to 16% wind and 9% sea).  A gull colony that formed on the southern part of island in 1985 resulted in that part of Surtsey having a biomass level 10 to 40 times great than in the barren portion of the island; the grassland that has formed as a result is now more than 10 ha (25 acre) in size, growingly rapidly, and can be seen easily from satellite photos.  With Atlantic puffins and meadow pipits have also established their own nests on the islandover the past decade, the amount of vegetation is expected to further increase.  69 species of plant have now been documented on Surtsey, of which 32 have become entrenched (a difficult task in the barren, nutrient-deficient ground).  (Click here for a photo gallery of vegetation from the official Surtsey research website.)

In addition to birds, seals are commonly found on Surtsey, particularly the north spit which has been used as a breeding ground since at least 1983.  Insects were present on Surtsey also from the beginning, with flying insects arriving first followed by bugs and spiders that came via driftwood, washed-up animal carcasses, and floating chunks of grass and soil that had broken off from nearby landmasses and washed ashore.  Fungi in the form of mosses were seen by 1967 and lichens were present in 1970; today, these cover much of the island.  The colonisation continues with earthworms and slugs now present since the 1990s.

This is not to say that human interference hasn’t been detected.  During the mid-1970s, an improperly discarded bowel movement from someone who had been eating tomatoes led to a tomato plant taking root in the soil; it was quickly removed once discovered.  Later in the 1970s, a group of boys from Heimaey snuck onto the island by boat and planted some potatoes; these, too, were removed.

Below, a Radio-Canada piece on Surtsey.  (NOTE:While the video is narrated in French, the interviews are conducted in English and readily understood even with overdubbing.)

Further Reading

Blask, S. (2008).  Iceland’s new island is an exclusive club – for scientists only.  Christian Science Monitor, 24 October 2008.  Available at http://www.csmonitor.com/The-Culture/2008/1024/iceland-s-new-island-is-an-exclusive-club-for-scientists-only.  Accessed 26 May 2012.

Magnússon, B., S.H. Magnússon, and S. Fridriksson (2009).  Development in plant colonization and succession on Surtsey during 1999-2008.  Surtsey Research 12: 57-76.  Available at http://www.surtsey.is/SRS_publ/2009-XII/low_res/2009-XII_057-076_Developments–lw.pdf.  Accessed 26 May 2012.

Petersen, Æ. (2009).  Formation of a bird community on a new island, Surtsey, Iceland.  Surtsey Research 12: 133-148.  Available at http://surtsey.is/SRS_publ/2009-XII/high_res/2009-XII_133-148_Formation–hi.pdf.  Accessed 26 May 2012.

Surtsey Research Society (2012).  Surtsey – The Surtsey Research Society.  Available at http://www.surtsey.is/index_eng.htm.  Accessed 26 May 2012.

UNESCO World Heritage Centre (2012).  Surtsey.  Available at http://whc.unesco.org/en/list/1267.  Accessed 26 May 2012.

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