Iceland is formed by spectacular contrasts of rugged landscapes: crystal blue ice caves, natural hot springs, mesmerising waterfalls and blasting volcanoes.
The land of Fire and Ice hosts a number of volcanic systems, most of which have exploded at one point during their existence. Some are considered dormant, whilst others, like the most recent eruption of Fagradalsfjall in 2021, are still closely monitored.
Want to learn more about Iceland’s volcanoes? How many are there, the frequency of their eruption and the most dangerous ones amongst them all? If so, then read on.
Why Are There Volcanoes in Iceland?
Iceland’s volcanic activity is due to the country’s geo location, sitting directly on the Mid-Atlantic Ridge, that separates the North American and Eurasian tectonic plates. These tectonic plates are detached one from another allowing magma to fill the space that is created. This results in the creation of one or more volcanic systems, that, once filled up are ready release pressure and produce a volcanic eruption.
Number, type and frequency of eruptions
Iceland is home to 32 volcanic systems, comprising of about 130 active and dormant volcanoes, which cover the entire territory except for the Westfjords as the no longer show any volcanic activity. 18 of them have shown activity and recorded eruptions during the country’s existence. Some of them are considered to be extinct because they have not erupted for more than 10,000 years and are not expected to do so in years to come.
The most common volcanoes in Iceland are composite or stratovolcanoes, which extend in a line and often over large areas. Shield-shaped volcanoes, which have the shape of a warrior’s shield placed on the ground, are also common. The 1963 eruption of Surtsey in the Westman Islands is a good example of a shield volcano.
There are caldera eruptions such as Askja and flat mountains such as Herðubreið, known as the Queen of the Mountains! Glorious Hekla is a stratovolcano. There have been many fissure eruptions, the most famous being the eruption of Eyjafjallajökull. Katla volcano has also ejected the largest volume of lava from a single eruption in the world.
Volcanic eruptions in Iceland are unpredictable, but occur fairly regularly and, although not accurately predicted, can to a certain extent be anticipated. The last known eruption in Iceland that occurred in March 2021 was Fagradalsfjall on Reykjanes Peninsula. The subglacial stratovolcano Bárðarbunga erupted in 2014. Grimsfjäll also recorded a brief eruption in 2011, while the better-known Eyjafjallajökull volcano caused worldwide airspace disturbances in 2010.
According to data collected by geologists, there have also been numerous subglacial volcanic eruptions in different parts of the country in the last 10 years that have not broken the ice sheet at the surface, such as Katla in 2017.
How dangerous are Iceland's volcanoes?
Because of their unpredictability, glacial floods known as jökulhlaups, remain one of the most dangerous aspects of Icelandic volcanic activity. As mentioned above, eruptions under the ice are not always detected, so these flash floods can occur without warning. Although most volcanoes are far from densely populated areas, there’s always a risk of them reaching urbanised regions. Even if this happens, Iceland’s emergency measures prove extremely effective, as seen in the 1973 eruption at Heimaey on the Westman Islands.
Heimaey is the only inhabited island there and is a volcanic archipelago. At the time of the volcanic eruption, there were more than 5200 people that lived nearby. In the early hours of January 22, a fissure began to open on the outskirts of the town and lava spewed through the center of town, destroying roads and swallowing hundreds of buildings. Although this occurred late at night and in the dead of winter, the evacuation of the island was carried out quickly and efficiently with the help of rescue teams from the US Army. By continuously pumping seawater into the lava flow, they not only managed to divert it away from many houses, but also prevented the harbor from being blocked, which would have been disastrous for the evacuation process as well as the Icelandic economy.
Iceland's most active volcanoes
This list of volcanoes in Iceland includes active and dormant volcanic mountains, of which 18 have erupted since human settlement of the country began around 900 AD.
The most famous and active volcano in Iceland is mount Hekla, which has erupted 18 times since 1104, the last time in 2000. The name Hekla is believed to derive from “lace”, a sleeveless garment, which the mountain resembles . Interestingly enough, in Icelandic “lace” is “að hekla”, so there seems to be a linguistic connection as well.
Hekla is considered and referred to as the “Gateway to Hell”. In the Middle Ages, Europeans often referred to Hekla in this way as they feared the destruction that the eruption of this volcano could cause.
In the 16th century, the German scholar Caspar Peuker wrote that the gates of hell were found in the “the bottomless abyss of Hekla Fell”.This was a place of purification where the souls of criminals, infidels and those who had drowned or died in a brutal way, carrying their devils and demons on their backs, went. It is said that the devil roamed the ice with their souls, roasting them in the fire. The picture described is highly demonic: it is said that the meetings of the witches were held on Hekla, that black as coal ravens with iron beaks flew around the hellfire of Hekla. It is still believed that witches gather on Hekla for Easter.
Katla is the name of a famous witch and sorceress who was the housekeeper of the abbot of Þykkvabæjarklaustur. Legend presents her as a big and bad woman who possessed a pair of magic breeches. When she wore them, she could run faster than the wind and never tire.
Many feared Katla and were wary of her. Barði was the Abbot’s shepherd, but in Katla’s eyes he could do no good and often incurred her wrath. One day when Barði could not find the sheep that Katla had ordered him to bring, he despaired and put on her magic breeches. With them he was able to escape the wind, and very soon he brought all the sheep home. When Katla returned, she realised that he had borrowed her clothes, her rage knew no bounds, and she drowned him in a vat of whey, letting his body sink to the bottom. In order to hide her crime, every time she approached the vat of whey, people would hear her mutter, “Barði will appear soon,” of course, she knew he could not appear.
When she realized that her secret was about to be revealed, she put on her breeches and rushed up to Mýrdalsjökull , where she threw herself into a canyon, and it has been called “Katla’s Canyon” ever since. Soon after, a huge and terrible glacial flood was unleashed, inundating the entire southern coastal area. Thus the huge and terrifyingly active volcano below Mýrdalsjökull was named Katla, and people speak of the cruel deeds of the evil witch Katla. Katla, has erupted about 20 times since the settlement of Iceland.
Eyjafjallajökull also erupted in 1612, and there was a series of eruptions between 1821 and 1823. There were medium-sized jökulhlaups or glacial runs, and the ash contained an unusually large amount of fluorine, which above a certain dose is toxic to both humans and livestock.
The 2010 eruption of Fimmvörðuháls, which preceded that of Eyjafjallajökull by several days, was not a subglacial eruption. At the northern end of the Fimmvörðuháls pass, at the hiking trail between Þórsmörk and Skógar, a 0.5 km long fissure has opened. Two new craters have formed, which are named Móði and Magni after the sons of Þór, the Norse god of thunder. The new lava field is called Goðahraun.
Eyjafjallajökull is the stratovolcano whose name rolled off the tongues of news readers when the ash from the 2010 eruption restricted international flights. In late February, unusual seismic activity and rapid crustal expansion warned that the magma chamber was filling rapidly. On April 14, 2010, an eruption began from the crater beneath the ice cap, the resulting glacial runs disturbing local rivers, and 800 people were evacuated. Electrical storms led to some spectacular lightning shows. These were accompanied by loud explosions as melted water entered the volcanic vent. The ice water caused the lava to fragment into extremely fine silica particles, which are particularly dangerous to aircrafts. This thin ash rose unusually high into the upper atmosphere. The wind then carried it into the world’s busiest air traffic zones resulting in the partial closure of international airspace.
Grimsvötn is a basaltic central volcano located in the mountains of southeastern Iceland beneath the Vatnajökull glacier, which has erupted more frequently than any other Icelandic volcano. Most eruptions are below glaciers. The system extends more than 100 km from southwest to northeast and is more than 20 km wide, making it the longest volcano in Iceland.
Before modern scientific geological findings, people knew very little about this volcano. The caldera is 650 m deep and the lake in the middle is considered one of the most particular geological formations in the world. Every few years, the ice shell breaks, unleashing a major flood known as Skeiðarárhlaup, where the surface of the lake drops by 100 m, causing a sudden drop in pressure that triggers increased earthquakes. Sometimes this occurs several weeks after the eruption has ended, when the caldera’s capacity to hold the melted water has been substantially exceeded. In 1996, a fairly large section of the Ring Road was washed away. Although the eruption had stopped, geologists knew that a major flood was imminent and closed the road. At least nine eruptions occurred in the 20th century, although none occurred between 1938 and 1983. There were eruptions in 1996, 1998, 2004 and 2011. The most recent eruption was much larger than predicted.
Askja is a 50km2 caldera (sunken crater), in the Dingüfjöll mountains, and a part of the central highlands in North Iceland. The region is home to a plethora of craters and stunning natural landscapes. It is the centre of a volcanic system with numerous fissures, including the Sveingjár crater line.
Like most volcanoes, the mountains were formed during eruptions under an ice cap through the glacial period. Askja itself was formed for the most part at the end of the glacial period in a major ash eruption that led to the collapse of the magma chamber roof at the heart of the central volcano.
A deep circular depression was left, which gradually began to fill with lava from subsequent eruptions along the rim of the depression. At present, the bottom of Askia is 1100 m above sea level, while the rim is 1300-1500 m above sea level. The term Askja (the Icelandic word for caldera) is used in the names of many similar formations elsewhere. Lake Askja is the deepest lake in Iceland with a depth of over 200 m. It was formed in 1875 when a powerful eruption took place in the southern part of the caldera. In just a few hours, almost 2.5 cubic kilometres of volcanic material poured out of the spring. The process was similar to the sequence of events that originally created Askja. After the eruption, the ceiling of the magma chamber began to lower, finally stopping at almost 250 meters below its original level. The depression filled with groundwater and formed Lake Askja.
Between 1922 and 1929, several small eruptions occurred around the edge of the new depression. Askia has erupted several times in history. After 1875 it played an important role in driving people out of East Iceland. The most recent eruption at Askja was in 196. American astronauts trained in this area – the landscape was thought to be similar to that of the Moon. Askja is still active and its base continues to gradually sink. This unique natural phenomenon is certainly alive and will continue to remind people from time to time that Iceland is still in a state of constant geological formation.
Iceland's most recent eruption
Fagradalsfjöll is the first active volcano in the UNESCO Reykjanes Global Geopark area in 800 years. It became a very talked about topic worldwide on 19 March 2021 when an eruptive fissure opened in the Geldingdalir valley. The eruption was active for a full six months and was declared over on September 21st, 2021.
The fissure was initially reported to be up to 700 metres long, with a lava field covering about one square kilometre, before soon forming into an increasingly taller crater. Although no one knew exactly where or when the volcanic eruption would occur, it had been declared inevitable after more than 53,000 tremors rocked Reykjavík and its surroundings in the preceding weeks. Although one of these tremors reached 5.7 on the Richter scale and several others came close, there were no significant injuries. The eruption itself poses little to no threat on infrastructure or airspace for two main reasons. Firstly, lava is not erupting from the ground in an explosion of ash, rock and fire as with Eyjafjallajökull. Instead, the eruption appears as an open fissure, releasing much softer lava flows in the form of molten rivers. Secondly, the eruption occurs in a relatively sheltered valley – Geldingdalur is mostly uninhabited and without significant infrastructure, making it one of the most convenient locations for hosting volcanic activity in the region.
Iceland has 130 volcanoes, with an eruption occurring on average once every 4 to 5 years. Whilst past eruptions have caused devastation and disruption in other countries, they have become more predictable with closer monitoring and advance in technology. Although country’s most recent eruption Fagradalsfjall is considered to be over, another one is just around the corner.