The Geology of Iceland

At the meeting of two plates

The Mid-Atlantic Ridge runs the length of the Atlantic Ocean and marks the boundary between the North American and Eurasian plates. The plates move apart by almost two centimetres a year, and magma rises into the resulting gap to form new crust. In Iceland the plate boundary can be seen with the naked eye, for example at Þingvellir, where Almannagjá and other fissures mark the eastern edge of the North American plate. In the Silfra fissure you can dive or snorkel in crystal-clear spring water between the plates.

A hotspot beneath Iceland

The ocean ridge alone does not explain why Iceland rises above the sea. Beneath the country is a mantle plume, a so-called hotspot, where unusually hot material rises from the Earth's mantle. The combination of the ridge and the hotspot means that magma production here is many times greater than elsewhere along the ridge, and so an entire country has formed. The centre of the hotspot is thought to lie beneath northwestern Vatnajökull.

The age of the land

Iceland is a young country. The oldest rocks are in the Westfjords and in the far east of the Eastfjords, about 13–16 million years old. The closer you get to the volcanic zone, the younger the rock, because the land is still forming there. The bedrock is usually divided into four formations:

Earthquakes

Earthquakes are frequent in Iceland, but most are small and not felt. The largest occur in two transform zones: the South Iceland Seismic Zone and the Tjörnes Fracture Zone in the north. The South Iceland earthquakes of 2000 and 2008 caused considerable damage to buildings but no loss of life. In the great South Iceland earthquake of 1784, however, hundreds of farms collapsed. Although earthquakes are common, Icelandic buildings are built to strict earthquake-resistance standards.

Geosites and geoparks

• Surtsey – an island formed in an eruption in 1963–1967 and added to the UNESCO World Heritage List in 2008. Scientists study how life colonises it.
• Columnar basalt – hexagonal columns form when lava cools slowly; well-known places include Svartifoss, Reynisfjara, Stuðlagil and Hljóðaklettar.
• Katla UNESCO Global Geopark – Iceland's first geopark, recognised in 2011.
• Reykjanes UNESCO Global Geopark – recognised in 2015, where the plate boundary comes ashore.
• Ásbyrgi – a horseshoe-shaped canyon thought to have been carved by catastrophic floods in the Jökulsá á Fjöllum river.
• Pseudocraters – e.g. Skútustaðagígar at Mývatn, which formed when lava flowed over wetland.

Icelandic earth science on the world stage

Icelandic earth science is respected worldwide. Several international scientific terms are Icelandic in origin, such as "geyser" and "jökulhlaup", which are used in scientific papers in many languages. The Institute of Earth Sciences at the University of Iceland and the Icelandic Meteorological Office carry out extensive research on volcanoes, earthquakes and glaciers.