Volcanic eruption is a natural phenomenon considered a means of observing what happens inside the Earth despite generally representing major natural disasters.
Many of us believe volcanoes erupt under or from inside the mountains. However, a volcano can erupt under an ice sheet or underwater. Such volcanoes are called Subglacial Volcanoes.
These subglacial volcanoes are very different from the other types, as they usually have steep sides and a flat top. Volcanoes that erupt under the ice can be highly explosive and produce a lot of fine ash.
Due to their proximity to glaciers, these volcanoes are more common in Antarctica and Iceland, although some older volcanoes are found in Canada.
One such example of volcanic eruption is the Icelandic Bardarbunga volcano eruption of 2014 and the Eyjafjallajokull volcano eruption of 2010.
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History of Volcanic Eruption under Ice Sheet (Subglacial Volcano)
1. Iceland’s Bardarbunga volcano eruption, 2014
On the surface of the mighty ice sheet, one can hardly imagine anything of the 700-meter-deep collapse crater, the caldera.
Over a width of one kilometer, lava flowed from a crevice in the Holuhraun lava field three kilometers to the northwest.
In the course of the eruption, the lava field had reached a size of 85 sq km. It is roughly equal to the area of the Portuguese capital Lisbon.
During the roughly six-month eruption, the caldera of the Bardarbunga, hidden under the ice, sank by another 40 to 60 meters. Luck was that the lava did not rise vertically and emerged from under the glacier.
If it had come into contact with suddenly released masses of meltwater, there would have been a devastating water vapor explosion. So the eruption was “peaceful.” It was partly due to the relatively thin basaltic magma erupting in Iceland.
2. Eyjafjallajokull volcano eruption, 2010
When the Icelandic Eyjafjallajokull volcano erupted in 2010, it emitted a giant ash cloud that paralyzed airports in most Europe for six days. The authorities canceled more than 100,000 flights.
According to Oxford Economics Study for Air travel, air traffic impacts the economy by around five billion dollars. Tourism in Iceland also came to an almost complete standstill.
The number of foreign tourists fell by 22 percent in April and 15 percent in May compared to 2009.
Nine months after the eruption, authorities in Reykjavik officially declared the eruption to be over.
The Eyjafjallajokull off the south coast of Iceland is one of the largest glaciers on the Atlantic island, with a height of 1,666 meters and an area of around 80 square kilometers. It hides a volcano underground.
The previous eruption under Eyjafjallajokull in 1821 lasted about 13 months. About 30 volcanoes are active in Iceland.
3. Deception Island Volcano Eruption, 1969
Deception Island belongs to the South Shetland Archipelago in the Southern Ocean. It is situated about 120 km north of the Antarctic Peninsula.
Deception features a horseshoe-shaped caldera that formed over 10,000 years ago during an explosive eruption that emitted more than 30 sq km of material.
It was discovered by British Captain William Smith in 1820 and was later used in seal and whale hunting before finding its modern vocation as a scientific and tourist site.
Once coveted by the United Kingdom, Chile, and Argentina, Deception offers an exceptional enclosed environment to study and monitor a “volcano under the ice.”
However, two successive eruptions in 1967 and 1969 surprised everyone and caused severe damage to existing scientific infrastructures.
The island has a glacier about 100 meters thick that sits on the ocean floor. During its ascent, lava moves slowly and has high water content.
As a result, it causes the glacier to melt, which, in addition to steam, pours out mudflats that have destroyed the British and Chilean science stations.
Future Subglacial Volcanoes Waiting to Awake- Antarctica
Scientists and volcanologists knew that Antarctica’s ice sheet hides an extensive system of volcanoes comparable to those in eastern Africa and North America.
Over the years of studying Antarctica, scientists have discovered 47 volcanoes.
Experts from the University of Edinburgh made the recent discovery of more volcanoes.
In August 2017, experts discovered a cluster of 91 more volcanoes 2 km below the ice sheet in West Antarctica.
If any of these volcanoes begin to erupt, scientists say it will destabilize the glaciers in western Antarctica.
Anything that can cause ice to melt will cause the melted ice to drain into the sea. So the main question now is, how active are these volcanoes?
The discovery will help scientists understand how volcanoes can influence long-term variations in the ice sheet.
“A better understanding of volcanic activity may explain its impact on past, present and future ice in Antarctica and on other rift systems [plate tectonic separation zones] that give rise to volcanoes around the world,” said the geologist Robert Bingham, professor at the University of Edinburgh, in a statement.
How many of the volcanoes are active is not yet known. Still, the volcanic activity could increase if the ice in Antarctica melts– which is possible, according to experts, considering the current global warming scenario, in which the region is the most affected in the world.
Grimsvotn volcano, Iceland
The Grimsvotn is one of the most active volcanoes in Iceland but mostly remains invisible because its eight-kilometer crater is generally covered by the approximately 200-sea-thick ice sheet of the Vatnajokull glacier.
As a result, the eruptions of the Grimsvotn harbor a double risk: They can emit vast clouds of steam and ash and cause destructive floods of meltwater.
Now there are increasing signs that another major eruption is imminent on Grimsvotn.
According to the Icelandic Meteorological Office, the weather authority responsible for volcanoes, there are several indications of increasing volcano activity.
The earthquakes’ frequency was significantly higher than usual, and the crater’s subsurface rose significantly. The degree of this uplift is already surpassing that of the 2011 eruption.
Another sign of eruption is the increased release of volcanic gases in the glacier area above Grimsvotn.
The heat flow and geothermal activity in the volcanic area have increased, which are considered to be the signs of an impending volcanic eruption.
The volcanologists are also concerned about another symptom: the water level in the subglacial lake above Grimsvotn has risen significantly.
The increasing volcanic heat melts the glacier ice and causes this 100-meter deep reservoir to fill up.
In the meantime, the level has already reached higher values than in 2004 and 2010, as reported by the Meteorological Office.
It means that there is now a risk of such a flash flood. Should that happen, it could provoke an outbreak of the Grimsvotn.
Because if the meltwater lake above the volcano suddenly empties, there is a sudden pressure relief, which destabilizes the volcano and causes the eruption.
A consequence of Volcano Eruption under Ice Sheet
Volcanoes under snow and ice cover pose particular risks, as sudden snowmelts can trigger mudflows.
When a volcanic eruption occurs, gases such as water vapor, carbon and sulfur dioxide, and hot rock are generally released.
In the case of glaciated (subglacial) volcanoes, however, the hot rock slurry (magma) often encounters a very thick layer of ice. In these contact areas, the ice is melted and hollowed out.
The ice layer sinks from above, and a trough filled with meltwater is created. Post-flowing lava is cooled extremely quickly when it comes into contact with the glacier water, creating oval rock structures, which are also known as pillow lava.
However, these pillows break and fall down the volcano’s slopes in these eruptions.
In its first phase, the magma melts part of the glacier and forms a cavity filled with water in the lower part of it.
Over time the eruption can break through the glacier and create a lake. If the eruption is persistent, the volcano increases in size as it expels lava and melts the ice more and more, creating a significant layer of water on the glacial surface and emitting a cloud of ash.
The last time there was a massive volcanic eruption under the ice, it occurred at the Grímsvotn volcano (which is not far from Bardarbunga ) in 1996, and it burned through about 2,000 meters of ice.
Researches Indicate melting ice sheets and glaciers could increase the frequency of volcanic eruptions in glaciated areas.
Based on a study published in Nature Communications, volcanic eruptions cool the global climate, but they can also increase the melting of ice sheets.
Researchers analyzing ice cores and meltwater reservoirs found that ancient eruptions caused immediate and significant ice sheet melting that covered much of northern Europe at the end of the last ice age.
“Over a period of 1,000 years, we found that volcanic eruptions generally correspond to greater melting of the ice sheets in about a year,” says lead author Francesco Muschitiello, a research scientist at Columbia University’s Lamont-Doherty Earth Observatory in New York, United States.
These were not volcanoes that only erupted on, under, or near the ice sheet but were thousands of kilometers away in some cases.
The eruptions threw huge clouds of ash into the sky, and when the ash fell on the ice sheet, its darker color caused the ice to absorb more solar heat than average.
“We know that if you have darker ice, you reduce the reflectance, and it melts faster. It’s basic science. But so far, no one could demonstrate this direct link between volcanism and ice melt when it comes to ancient climates “. Muschitiello explains.
Muschitiello and his teammates studied a period ranging from 12,000 to 13,200 years ago when the last ice age transitioned to today’s warm climate.
They specifically focused on volcanic eruptions in high northern latitudes, similar to the 2010 eruptions of Iceland’s Eyjafjallajokull volcano.
Although that eruption was relatively minor, its massive ash cloud shut down air traffic in most of Europe for about a week.
Another interesting implication is that previous research suggested that melting ice sheets could augment the frequency of volcanic eruptions in glaciated regions by lightening charges on the Earth’s crust, allowing underlying magma to rise.
Suppose the link between volcanic eruption and ice sheet melting is found. In that case, it could indicate the presence of a “positive feedback loop” in which eruptions increase melting, and more melting causes more volcanic eruptions, and so on.
Muschitiello believes the study may reveal clues to the mechanisms at play at a time when rapid climate change is expected.
Volcanic eruptions under ice sheets are nothing new; history suggested the eruption of such volcanoes thousands of years ago. Numerous findings of the newly active volcano under the thick ice sheet of Antarctica and the glacier mountains of Iceland have placed the researchers on edge for the disastrous consequences.
Apart from being natural phenomena, these volcanic eruptions are also triggered by climate change and global warming.
Volcanologists suggested appropriate actions to minimize global warming to delay the eruptions of such volcanoes.
(Last Updated on April 17, 2022 by Sadrish Dabadi)