What causes a volcano to erupt? World watches as Iceland prepares for impending eruption


The world is watching as Iceland prepares for a possible volcanic eruption following more than several hundred small earthquakes that have affected the North Atlantic island country. 

The staggering seismic activity has shut down tourist spots in Iceland, fissured roads and prompted the Icelandic government to evacuate a town in the potential path of an eruption, according to multiple news sources. 

To answer questions about this type of natural phenomenon, Fox News Digital reached out to two science experts for insights and information.

Eruptions happen for a number of reasons.

Here’s what’s at work.

What causes a volcano to erupt? Are there precursors that cause an eruption or natural events that create the perfect storm for it to happen?

“Sometimes molten rock (magma) rises after it is formed within the Earth because it is less dense than the rock surrounding it. This is thanks to magma being hot and full of dissolved gases,” said Erik Klemetti, PhD, an associate professor of Earth and environmental sciences at Denison University in Granville, Ohio. 

Eruptions can be triggered by a number of events.

Magma will also form bubbles as it rises because the magma is feeling less pressure from the rock above it, he said. 

“Think of this like a bottle of soda, where twisting the cap releases pressure and bubbles form from all the carbon dioxide that was previously dissolved in the soda,” Klemetti added. 

Eruptions can be triggered by a number of events. 

Sometimes a new batch of magma will rise into a volcano and mix with existing magma, causing an eruption, he said.

“Sometimes it is just the pressure from magma accumulating in the Earth’s crust that causes an eruption to occur.”

What are the most recent US eruptions?

The most recent eruption in the U.S. is occurring right now, said Klemetti.

“Great Sitkin in Alaska is erupting small lava flows, while another three in Alaska are on elevated alert because they show signs of unrest like earthquakes,” he said.

“Kilauea in Hawaii is also on elevated alert, having last erupted in September of this year,” he also said. 

“At any given moment, there are anywhere from 8 to 12 volcanoes erupting on our planet.”

What must people know about the potential eruption right in Iceland?

Iceland is one of the most volcanically active places on Earth, Dr. Klemetti said.  

The Reykjanes Peninsula, where the current earthquakes are happening, has experienced two sets of eruptions over the past few years, he said. 

If it happens, “we’ll likely see lava flows and fountains similar to what happens in Hawaii.”

“This new unrest near Grindavik, mainly thousands of earthquakes a few miles beneath the surface, appears to be caused by magma rising up under the region,” he said.

The Icelandic Meteorological Office, which monitors volcanoes in Iceland, thinks an eruption is likely in the very near future, possibly within days.

“If that happens, we’ll likely see lava flows and fountains similar to what happens in Hawaii,” Klemetti said.

Do volcanoes occur in tandem with other disasters like earthquakes and tsunamis? 

Arianna Soldati, PhD, an assistant professor of volcanology in the department of marine, Earth and atmospheric sciences at North Carolina State University in Raleigh, told Fox News Digital that volcanic eruptions are almost always preceded by earthquakes. 

“People picture an empty volcanic conduit, and magma occasionally rising through it, but this is very rarely the case,” Soldati said.

“The Earth’s crust is solid, full. Magma has to open up its own pathway to reach the surface, and it does so by fracturing the crust and then filling those cracks. The fracturing creates earthquakes.” 

Volcanic eruptions are almost always preceded by earthquakes. 

Sometimes, volcanic eruptions can be accompanied by tsunamis — but only if the volcano is on the coast, on an island, or underwater, she noted.

“Tsunamis of volcanic origin are related to large amounts of material quickly entering the ocean: Think catastrophic flank collapse,” she said. 

“This is fairly rare.”

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