Iceland Volcano Eruption: Here's Everything to Know

Preparations continue in southern Iceland where the threat of a significant volcanic eruption has led to nearby residents being evacuated from their homes.

Authorities in Iceland have begun building earth walls around the town of Grindavik and a nearby power station to divert lava flows should an eruption occur.

Scientists have been monitoring the elevated tectonic activity since November 10, when a magnitude 4.1 tremor occurred followed by a burst of others. The changes prompted local authorities to evacuate the fishing town of Grindavik, on Iceland's southwest peninsula, while cracks have appeared in the ground and across roads in the area.

Magma has pushed up the ground by as much as an inch; a vertical magma intrusion that has formed close to Grindavik is said to be sitting on molten rock thought to be half a mile or less from the surface.

Meteorologists observing the situation have noted a decrease in magma inflow and seismic activity but have not yet dismissed chances of a surface eruption. With the help of volcanological expertise, Newsweek has examined the current situation and how disruptive such an eruption may be.

What Have Researchers Said?

As of Thursday, the Icelandic Meteorological Office said the likelihood of an eruption in the area near the town of Grindavík had been decreasing daily.

On Tuesday 300 earthquakes were detected along the region's magma intrusion, referring to areas where molten rock has risen up towards but not reached the earth's surface. By Wednesday, this reduced to 100 earthquakes.

Furthermore, the intensity of the earthquakes reaching above magnitude 2.0, referring to earthquakes that may not be felt but can be recorded, had decreased.

The rate of magma flowing toward the intrusion and changes to the crust around were also said to be diminishing. Crustal uplift in Svartsengi, a geothermal hotspot, near the capital Reykjavik, has continued at a similar pace.

Research modeling based on data from November 21 suggested that the influx of fresh molten rock into the magma intrusion was greatest near the Sundhnúkur crater row, about 2.5 miles northeast of Grindavík.

The Met Office added that while a volcanic eruption at some location along the intrusion continued, the likelihood of an imminent disruption was falling.

"Based on the latest data, and considering the evolution of activity since November 10, the likelihood of a sudden eruption within the Grindavík urban area is decreasing daily, and it is presently assessed as low," the Met Office said.

"It can be assumed that newly emplaced magma beneath Grindavík has solidified partially, thereby reducing the likelihood that the magma will reach the surface within the city limits.

"However, we emphasize that the possibility of a volcanic eruption at some point along the length of the intrusion, particularly between Hagafell and Sýlingarfell, remains plausible."

Is The Worst Over?

Geochemistry professor Thomas Algeo of the University of Cincinnati said that there was no simple answer to whether the worst of the volcanic activity in the region was over.

"After an 800-year interval of no eruptions in this region, activity resumed in the spring of 2021: for six months during 2021 and for briefer intervals during the summers of 2022 and 2023," he said.

"The chances are that, even if the present activity tapers off, there will be further eruptions in the Reykjanes Peninsula region during the coming years."

Algeo added, however, that large eruptions were infrequent, and that "as a matter of probability, any individual eruption is likely to be small."

Philip Collins of Brunel University London said the "immediate threat of an eruption has decreased."

"The earthquakes were a reflection of magma intruding into the rock fairly close to the surface, causing it to crack," he said.

"The fact that there are fewer earthquakes suggests less cracking which probably means the pressure of the magma has fallen. It may have cooled a little but, depending on how much magma there is and how well the surrounding and overlying rocks can act as an insulator, it may take a long time to turn into solid rock."

What Disruption Could This Earthquake Cause?

The last time a major eruption occurred in Iceland was in 2010, when the Eyjafjallajökull volcano erupted several times, causing a massive ash cloud to spread over Europe and North America. This led to severe disruption to air travel.

However, experts have said that, unlike 2010, eruptions in the Reykjanes Peninsula would not create disruptive ash clouds.

Algeo told Newsweek that ash and steam clouds were unlikely as there are no large ice caps in the region.

"The ash and steam clouds are a product of eruptions under ice caps, such as Eyjafjallajökull and Vatnajökull further to the east," Algeo said.

Collins added that magma in the region of the Reykjanes Peninsula contained relatively little gas, which affected the creation of ashy particles.

"In explosive eruptions, when the magma gets close to the surface, this gas expands rapidly as the pressure is lower and this can break the cooling magma into fine particles," Collins said.

"It can also happen if there is a lot of water around. If an eruption does happen in the Reykjanes area in the near future, it is very likely to be similar to nearby eruptions over the last couple of years.

"These have been dominated by lava flows. There will still be some gas but the main hazard from this is likely to be poor air quality in the locality.

"This is unlike the Eyjafjallajökull eruption of 2010, which included both lava and volcanic ash and caused major problems for air travel."

As of Friday, the Icelandic Meteorological Office has issued a code yellow aviation warning in the Reykjanes Peninsula.

This cautions plane operators to be alert to volcanic activity that has either increased beyond background levels or activity that's decreased but continues to be monitored. The Reykjanes Peninsula had only days ago received an orange warning, "heightened unrest with increased likelihood of eruption."

There have been three eruptions on the Reykjanes Peninsula: March 2021, August 2022, and July 2023. However, unlike the situation near Grindavik, those three were far away from populated areas.