Volcanic activities in Iceland

Shield volcanoes of the Hawaiian type, like Skjaldbreiður near Þingvellir, are also numerous, but the only one active in historical times was the new Surtsey volcano. Almost all the cone volcanoes of the Fuji type are ice-covered, the largest of them being Öræfajökull (2119 m), Eyjafjallajökull (1666 m), and Snæfellsjökull (1446 m). Craters created by volcanic explosion are also quite common.

The most famous Icelandic volcano is Hekla, which was renowned throughout the Catholic world in the Middle Ages as the abode of the damned. Since its first recorded eruption in 1104, which destroyed vast areas, including the Þjórsárdalur settlement, Hekla proper has erupted 17 times in historic times, continually causing damage to the surrounding countryside. At the beginning of its eruption in March 1947, columns 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, the lava flow lasting for a couple of months. Again, as recently as 1980 and 1981, there were series of eruptions.

The volcano Katla, hidden beneath the ice of the Mýrdalsjökull, 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 volume of water. Askja in the northeastern highlands last erupted in 1961, but its eruption in 1875 was the last to cause great damage in the country. This earlier eruption formed Öskjuvatn (Lake Askja), the deepest lake in Iceland (220 m deep).

The most dramatic recent volcanic eruption began the night of 23 January 1973 in the only inhabited island of the Westman group, Heimaey. In an outstanding operation, the entire population of some 5,300 were evacuated to the mainland in a matter of hours without any accidents. The eruption lasted until May and half of the town was submerged in lava while the rest was covered with thick layers of ash. The harbour and the most important fish processing plants were saved by the bold effort of Icelandic scientists to cool the encroaching lava flow with thousands of tons of sea water, 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 non-stop, and gradually most of the inhabitants returned to their much altered domicile.

Submarine eruptions are frequent off the coasts of Iceland, especially on the Atlantic Ocean ridge southwest off the Reykjanes peninsula. The last submarine eruption, near the Westman Islands, started visibly on 14 November 1963, creating three 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 utilizing 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 that went on for some weeks, damaging part of the fishing village Kópasker in the northeast in January 1976.

An eruption in the Westman Islands in 1973.

A geothermal field at Hveravellr, central Iceland.