Subglacial volcano

A subglacial volcano, also known as a glaciovolcano, forms when a volcano erupts beneath a glacier or ice sheet. The heat from the lava melts the ice above it, creating a lake of water. This water then quickly cools the lava, shaping it into special forms similar to those found underwater.

These volcanoes are most common today in Iceland and Antarctica, but older examples exist in British Columbia and Yukon Territory, Canada. In 1996, a volcano in Iceland called Grímsvötn melted a large amount of ice, causing a big flood.

Subglacial volcanoes have a unique shape, often flat on top with steep sides, because the surrounding ice and water support them. If the volcano breaks through the ice, it can leave behind flat lava flows. In Canada, these volcanoes can look either cone-shaped or flat, and the flat-topped ones are called tuyas, named after a place called Tuya Butte.

Jökulhlaups

Subglacial eruptions can cause big floods of water, called jökulhlaups. In November 1996, the Grímsvötn Volcano under the Vatnajökull ice sheet erupted and created a flood that covered more than 750 km². This flood damaged several bridges. Experts warn that when a volcano erupts under ice, the mix of hot lava, ice, and water can create very dangerous situations.

Antarctica eruption

In 2008, scientists from the British Antarctic Survey reported that a volcano erupted under the ice in Antarctica about 2,200 years ago. This was the largest eruption in Antarctica in the past 10,000 years. They found volcanic ash on the ice near the Hudson Mountains, close to Pine Island Glacier. The heat from the eruption melted the ice above it.

On Mars

Many scientists think there might be liquid water far below the surface of Mars. Right now, we can't drill deep enough with our rovers to check. Two scientists, Meredith Payne and Jack Farmer from Arizona State University, looked at pictures from the Viking and Mars Orbiter cameras. They searched for possible subglacial volcanoes that might bring tiny living things to the surface.

Ice cores

We can learn about big eruptions under ice by looking at ice cores, like the Vostok core. These eruptions leave special layers in the ice with lots of certain chemicals, such as NO⁻₃ and SO²⁻₄.