Iceland - The Volcanic Island

Iceland - The Volcanic Island

28.05.2021 | Bára Kristinsdóttir

Iceland’s landscape is shaped by a battle between the destructive nature of glaciers, wind and flowing water and the constructive nature of volcanic activity, leaving us with mountains, fjords, lava fields and numerous waterfalls. Iceland is located on the Mid-Atlantic ridge, a divergent plate boundary that stretches from North to South along the Atlantic ocean. In Iceland the Mid-Atlantic ridge meets the Iceland Hotspot, both contributing to volcanism in Iceland allowing the island to rise above sea level. 

On average, volcanic eruptions take place every 3-6 years in Iceland. The behaviour of the eruptions can be diverse, depending on the properties of the magma and its gases as well as the environment. Some take place on dry land, others below sea level or underneath a glacier. When magma needs to make its way through an ice cap or a body of water, the magma cools rapidly forming small particles, ash, that can be dispersed with the wind if the eruption makes its way above sea level or through the ice. In the Eyjafjallajökull eruption in 2010 the properties of the magma along with the fact that it needed to make its way through the glacier resulted in the formation of fine-grained ash that caused disturbance in flight traffic, grounding several thousands of people for days in northern Europe. 


On March 19th, 2021 a volcanic eruption started in Geldingadalir by Fagradalsfjall, North East of Grindavík on Reykjanes Peninsula. The eruption is small and even though it is located only some 20 km from Keflavík Airport, it hasn’t caused any significant disturbance in flight traffic to and from the airport. 

The eruption in Geldingadalir is the first volcanic eruption that has occurred on Reykjanes Peninsula in 800 years. For over a year prior to the onset of the eruption, there had been some indications of magma movements in the area. In late January 2020 several earthquakes occurred northeast of Grindavík, the largest one of magnitude 3,7. Inflation was also detected in the same area in late January and February, indicating accumulation of magma beneath Mt. Þorbjörn, close to Grindavík. 

Geldingadalir volcanic eruption 

Mid-March 2020, the uplift in Mt. Þorbjörn started again but at a slower rate than before. It decreased at the beginning of April and stopped in mid-April.

In July 2020, an earthquake swarm occurred by Mt. Fagradalsfjall, next to Geldingardalir. The activity had moved further northeast from Grindavík. The largest earthquake was of magnitude 5 but over 20 earthquakes of magnitude 3 or larger were detected during a two day period.

On October 20th, an earthquake of magnitude 5,6 occurred in Núpshlíðarháls, east of Mt. Fagradalsfjall. Around 1700 earthquakes were detected in the area during a 24 hour period but only four days later the activity had decreased significantly

An earthquake of magnitude 5,7 shook Reykjanes Peninsula on February 24th, 2021. It was followed by tens of thousands of earthquakes between Mt. Fagradalsfjall and Mt. Keilir in the next few weeks. The earthquakes occurred along a relatively straight line that stretched between the two mountains, interpreted by earth scientists as the formation of a magmatic dike. Just over three weeks after the large earthquake of magnitude 5,7, the magma reached the surface and a volcanic eruption started on the evening of March 19th, 2021.

Approximately 1200°C hot basaltic magma started flowing from a few hundred meters long fissure in a relatively small eruption. The fissure opened in a valley, Geldingardalir, far enough from any populated area for buildings or roads to be affected by the eruption, at least for the first months after the eruption started. It is however fairly accessible, only about an hour drive from central Reykjavík in addition to a 3-4 hour hike on rough paths.

At first scientists speculated that the eruption would not last very long based on the small volume of magma being erupted from the craters. Chemical analysis made on the newly erupted lava showed that it was relatively primitive indicating that it derived from the mantle and did not dwell in the crust for a long time before reaching the surface. It had some similarities with the lavas forming shield volcanoes, voluminous volcanoes that are formed in long lasting eruptions.

Only time will tell how long the eruption by Fagradalsfjall will last but over two months after it started it is not showing any indications of ceasing. New openings have opened along the fissures, craters have formed around the openings and then the activity has stopped at that particular crater. But the overall volume of magma being erupted per day was pretty steady during the first weeks but has been increasing, even though it's still of a relatively small volume.

A map was published in late April by the Institute of Earth Science at The University of Iceland comparing the volume of magma that has erupted in the five eruptions that have occurred in Iceland since the year 2000 as well as the area covered by lava. The map shows how small the eruption by Fagradalsfjall is compared to Holuhraun in 2014-2015 that lasted for about 180 days and Hekla in 2000 that lasted for 12 days.

Even though it's not a large eruption it is a spectacular one and thousands of people have visited Fagradaldfjall and Geldingadalir since the eruption started. But there are several things that one needs to bear in mind when visiting the active volcanic site since it is where you can witness Mother nature at work, and she can be unpredictable. 

Geldingadalir volcanic eruption 

Off road driving is prohibited as well as parking your car along road 427. Parking areas have been defined close to the beginning of the hiking trail, please park your car in the parking areas.

Check the weather forecast and dress accordingly. Weather in Iceland can change quickly. It is therefore ideal to dress in layers so you can easily add or remove a layer according to the change in weather. Put on a warm base layer, hat and mittens and waterproof pants and jacket. Wear hiking boots, sneakers are not ideal on the rough terrain. If you are travelling after dark, bring headlights with you. Hiking poles might also come in handy since you will be hiking on rough terrain. 

Geldingadalir volcanic eruption 

Bring water and some food with you. Even though the hike should only take around 3-4 hours, one should always assume that it might take longer.

Be aware that volcanic gases are emitted from the crater and the cooling lava. They can accumulate in low lying areas and valleys and can be a threat to your health. Stay on ridges and hills and avoid low lying areas, the gases can be colourless and hard to detect without a gas detector. Walk with the wind in your back when walking towards the eruption site but face the wind when walking back from the site. 

Geldingadalir volcanic eruption 

Stay on marked trails and do not enter closed off areas. Since the eruption started, new cracks have opened causing lava to flow in new places. Some areas close to the eruption are defined as danger zones since the fissures are most likely to open in these areas. Please stay on marked trails and follow the instructions of the police and ICE-SAR people. 

Geldingadalir volcanic eruption 

The outermost layer of the lava turns black when it solidifies, but do not be fooled because underneath it, molten lava might be lurking. It can burst through the black lava and move forwards at a fairly great speed, so don’t go too close to the lava. 

Geldingadalir volcanic eruption 

Bring a fully charged mobile phone and a GPS. The cell phone reception is poor in the area so if you don’t have a GPS, download the map of the trail beforehand. It is accessible on Safe Travel’s website

Geldingadalir volcanic eruption 

It is fascinating to get this close to an active volcano and see Mother nature in action, but you should always put yourself first. If you are not feeling well during the hike, please turn around instead of endangering yourself. Don’t hesitate to seek the assistance of the police or ICE-SAR people who can be identified by their colourful red, blue and yellow clothing.

There are other ways to see the eruption e.g., on a helicopter sightseeing tour, or simply just observe it from a distance.

Geldingadalir volcanic eruption 

Explore Hey Iceland Fire and Ice self-drive tour, where you discover the island‘s unique landscape on inclusive tour of Iceland‘s geological wonders AND see an active volcano with your own eyes.

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