The Fagradalsfjall volcano has been rumbling and causing earthquakes for a year, but over the past 72 hours, the situation has intensified. The volcano has been producing over 1,000 earthquakes a day, which researchers believe could be a sign of an impending eruption.

Fire and earth

Volcanic earthquakes are often a prelude to an eruption. They can indicate magma movement and a build-up of gas pressure within the Earth that can indicate an upcoming eruption. In the first part of Monday alone, there were around 900 earthquakes.

The 4,000 people in the nearby village of Grindavik had already been evacuated, forming lines that went on for kilometers. Even without an eruption for now, huge cracks formed in the ground, causing damage to buildings.

“The National police chief … declares a state of emergency for civil defence due to the intense earthquake (activity) at Sundhnjukagigar, north of Grindavik,” the Department of Civil Protection and Emergency Management said in a public statement.

“Earthquakes can become larger than those that have occurred and this series of events could lead to an eruption,” the administration warned. Just a few residents were allowed to enter their homes for no more than five minutes to pick up personal belongings.

A tunnel of magma

In 2021, the Fagradalsfjall volcano erupted for the first time after a slumber of over 6,000 years. It created fountains of lava and striking flows. But scientists fear an even larger eruption may be upcoming.

The volcano lies in the Reykjanes peninsula, some 20 miles (32 km) from the capital Reykjavik. Geophysical measurements suggest that a tunnel of magma some 9 miles long (14.5 km) was connected to the volcano, feeding it with magma and creating the earthquakes and pressure build-up. If this is the case, the likelihood of an eruption is pretty high. The fact that some earthquakes were already over 5 degrees magnitude also suggests some serious activity.

However, it is not clear where the eruption would happen (if it does happen). There is a chance that it could happen at sea or farther away from Grindavik. However, authorities are not taking any risks.

Volcanologist Armann Hoskuldsson told state broadcaster RUV: “This is very bad news. One of the most serious scenarios is an eruption in the town itself, similar to that in Vestmannaeyjar 50 years ago. This would be much worse.”

Iceland is shaking

If an eruption does happen, it could take weeks for it to unfold. At this time, there are few guarantees. If it does happen, it will likely not be as bad as the 2010 eruption of the Eyjafjallajokull volcano. Even so, it could well obliterate Grindavik, which lies very close to the volcano’s activity.

So how likely is an eruption?

Magnús Tumi Guðmundsson, a professor of geophysics, told RÚV the chances of an eruption were considerable. The seismic activity “started off really fast and thankfully has slowed down a bit”, he said. “However, that does not tell us anything about what happens next.” The eruption could happen near the town or — less likely — out at sea, he said.

Iceland is by far the most volcanically active country in Europe. The country is uniquely positioned atop the Mid-Atlantic Ridge, where the North American and Eurasian tectonic plates are slowly drifting apart. This divergent plate boundary is a seam in the Earth’s crust, where new crust is continually being formed as magma rises from the mantle below. The movement of these plates creates fissures and cracks, allowing magma to reach the surface, leading to frequent volcanic eruptions.

Adding to the tectonic drama is the Iceland hotspot, a plume of hot mantle material rising towards the surface. This hotspot fuels the volcanic fire, providing a steady supply of molten rock. When this magma finds its way to the surface, it results in the formation of volcanoes. The combination of the Mid-Atlantic Ridge and the Iceland hotspot makes the island one of the most volcanically active places on Earth.

There have been three eruptions on the Reykjanes peninsula since 2021. Thankfully, all have been far away from any infrastructure or populated areas.

The situation in Iceland is still unfolding. This article may yet be updated.