Volcanic Activity
Iceland has some of the most active volcanoes in the world. There are about 200 volcanoes, at least 30 of which have erupted since the country was settled in the 9th century AD. On the average there is an eruption every five years. Nearly every type of volcanic activity found in the world is represented in Iceland, the most common being fissure eruptions. One of these, the 30km-long row of craters, Lakagígar, with about 100 separate craters, erupted in 1783. The gases and ashes from this eruption poisoned the grasslands, causing tremendous damage to the countryside. This brought widespread famine and resulted in the deaths of tens of thousands of people through starvation. The lava flows from this eruption are the largest in the world, covering 565 square km.
Shield volcanoes of the Hawaiian type, like Skjaldbreiður near Thingvellir, are also numerous, but the only active one in historical times is the recent Surtsey volcano. Almost all the cone volcanoes of the Fuji type are ice-covered, the largest of them being Öræfajökull (2,119 m), Eyjafjallajökull (1,666 m), and Snæfellsjökull (1,446 m). Craters created by volcanic explosions are also quite common.
The most famous Icelandic volcano is Hekla, which was renown throughout the Catholic world during the Middle Ages as being the gateway to hell. Since its first recorded eruption in 1104, which destroyed vast areas, including the Þjórsárdalur settlement, Hekla has erupted 17 times in recent times continually causing destruction to the surrounding countryside. At the beginning of its eruption in March 1947, a column of smoke and ash rose to 100,000 feet. The eruption lasted 13 months. In May 1970, a number of small craters in Hekla erupted and the lava flow lasted for some two months. There were also a series of eruptions as recently as 1980, 1991 and 2000.
The volcano Katla, hidden beneath the ice of the Mýrdalsjökull glacier, has erupted at least 13 times since the settlement of Iceland, last in 1918. The eruptions of sub-glacial volcanoes cause massive floods which in the case of Katla may exceed the Amazon river in the volume of water. It is well over due to erupt. Askja, in the northeastern highlands, last erupted in 1961, but its eruption in 1875 was the last one to cause great damage. The eruption formed Öskjuvatn (Lake Askja) - the deepest lake in Iceland at 220 m deep.
The most dramatic recent volcanic eruption began on the night of 23 January 1973 in the inhabited Westman Islands. In an incredible operation, the entire population of some 5,300 people was moved to the mainland in a matter of hours, without incident. The eruption lasted until May and half of the town was submerged in lava while the remainder was covered by a thick layer of ash. The harbour and the most important fish-processing plants were saved through a bold experiment by Icelandic scientists, which consisted of cooling the encroaching lava flow by pumping thousands of tons of sea water onto it, which eventually succeeded in stopping the flow. As a result of the eruption, the island was considerably enlarged and the harbour vastly improved. Rescue and restoration work went on ceaselessly, and gradually most of the inhabitants returned to their much-altered domicile.
Sub-marine eruptions are frequent off the coasts of Iceland, especially on the Atlantic Ocean ridge southwest of the Reykjanes peninsula. The last sub-marine eruption, near the Westman Islands, began visibly on 14 November 1963, and created three new islands. One of the islands endured and was named Surtsey. The eruption continued for more than seven years.
Earthquakes are frequent in Iceland, but rarely dangerous. The most disastrous ones occurred in the southern lowlands in 1784 and 1896, leaving many farms in ruins. The village of Dalvík in Eyjafjörður, in the north, was partly destroyed by an earthquake in 1934. A minor volcanic eruption near Krafla in the northeast, where the first major power station utilising natural heat was under construction, started in December 1975, and continued off and on for a number of years. Most recently, there were severe earthquakes in January 1976 that went on for some weeks, damaging part of the fishing village Kópasker, in the northeast.