Experts said a volcano in Iceland’s countryside may be preparing to erupt.

The volcano called Grímsvötn is the most active on the island and is almost completely covered in ice.

It last erupted in 2011 and released a cloud of ash into the air at an altitude of 12 miles (20 km), causing 900 flights to be canceled.

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Plumes of smoke from Grimsvoten volcano, which is located under the Vatnajökull glacier, about 120 miles (200 km) east of the capital, Reykjavik, which erupted in 2011

The eruption of Grimsvoten volcano sends thousands of tons of volcanic ash into the sky on 23 May 2011 over Iceland.

Another Icelandic volcano, Eyjafjallajökull, erupted in 2010 causing further disruptions, disrupting about 100,000 flights.

This is despite the fact that Eyjafjallajökull is much smaller than Grímsvötn.

Scientists have recorded signs of disturbances in the area, where seismic activity indicates swelling of magma in the volcano’s tubes.

Dr Dave McGarvey, a volcanologist at Lancaster University, adds in an article by Dr. Conversation: “The increased thermal activity has caused more ice to melt, and there has also been a recent increase in earthquake activity.”

It last erupted on Grímsvötn in 2011 (pictured) and released an ash cloud 12 miles (20 km) into the air, causing 900 flights to be canceled.

All of these signs indicate an impending eruption, and the next sign that experts are watching is “a severe swarm of earthquakes lasting for a few hours”.

This will indicate that the magma is moving up and preparing to erupt.

The Icelandic Meteorological Office (IMO) has already increased the volcano’s flight color code from green to yellow as a precaution.

This is evidence that experts fear an upcoming eruption that would later cause mild disruption to air travel.

In a statement, the International Maritime Organization said: “Multiple data sets now indicate that Grímsvötn volcano has reached a level of turbulence.”

The city of Grímsvötn experiences a massive eruption, like that of 2011, about once every century. But, according to Dr. McGarvey, she has smaller bangs roughly once every decade.

If Grimsvoten’s previous pattern of large occasional eruptions continued with more volcanic eruptions occurring in the future, then the next eruption should be small (given a large eruption in 2011).

Grímsvötn’s ice ceiling means that volcanic eruptions are not as catastrophic as those that have occurred at other volcanoes.

Ash from the explosion collides with a wall of ice, which can be up to 850 feet (260 meters) thick, and coalesce.

Instead of being a soft debris remaining in the atmosphere, it becomes wet and sticky and drops from the air quickly, which limits turbulence and damage.

“Therefore, clouds of ash travel only a few dozen kilometers from the site of the explosion,” says Dr. McGarvey.

“This is a good scenario for Icelanders as well as for air travel, because it prevents the formation of large ash clouds that could drift off and block the airspace.”