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Geology

A geologically young land at 16 to 18 million years old, Iceland is the surface expression of the Iceland Plateau, a large igneous province forming as a result of volcanism from the Iceland hotspot and along the Mid-Atlantic Ridge, the latter of which runs right through it. This means that the island is highly geologically active with many volcanoes including Hekla, Eldgjá, Herðubreið, and Eldfell. The volcanic eruption of Laki in 1783–1784 caused a famine that killed nearly a quarter of the island's population. In addition, the eruption caused dust clouds and haze to appear over most of Europe and parts of Asia and Africa for several months afterwards, and affected climates in other areas.

Iceland has many geysers, including Geysir, from which the English word is derived, and the famous Strokkur, which erupts every 8–10 minutes. After a phase of inactivity, Geysir started erupting again after a series of earthquakes in 2000. Geysir has since grown quieter and does not erupt often.

With the widespread availability of geothermal power and the harnessing of many rivers and waterfalls for hydroelectricity, most residents have access to inexpensive hot water, heating, and electricity. The island is composed primarily of basalt, a low- silica lava associated with effusive volcanism as has occurred also in Hawaii. Iceland, however, has a variety of volcanic types (composite and fissure), many producing more evolved lavas such as rhyolite and andesite. Iceland has hundreds of volcanoes with about 30 active volcanic systems.

Surtsey, one of the youngest islands in the world, is part of Iceland. Named after Surtr, it rose above the ocean in a series of volcanic eruptions between 8 November 1963 and 5 June 1968. Only scientists researching the growth of new life are allowed to visit the island.

On 21 March 2010, a volcano in Eyjafjallajökull in the south of Iceland erupted for the first time since 1821, forcing 600 people to flee their homes. Additional eruptions on 14 April forced hundreds of people to abandon their homes. The resultant cloud of volcanic ash brought major disruption to air travel across Europe.

Another large eruption occurred on 21 May 2011. This time it was the Grímsvötn volcano, located under the thick ice of Europe's largest glacier, Vatnajökull. Grímsvötn is one of Iceland's most active volcanoes, and this eruption was much more powerful than the 2010 Eyjafjallajökull activity, with ash and lava hurled 20 km (12 mi) into the atmosphere, creating a large cloud.

A great deal of volcanic activity occurred in the Reykjanes Peninsula in 2020 and into 2021, after nearly 800 years of inactivity. After the eruption of the Fagradalsfjall volcano on 19 March 2021, National Geographic 's experts predicted that this "may mark the start of decades of volcanic activity." The eruption was small, leading to a prediction that this volcano was unlikely to threaten "any population centers".

The highest elevation for Iceland is listed as 2,110 m (6,920 ft) at Hvannadalshnúkur (64°00′N 16°39′W).