The merger of glaciers could trigger more explosive eruptions worldwide

The merger of glaciers can silently prepare the ground for more explosive and frequent volcanic eruptions in the future, according to research on six volcanoes of the Chilean Andes.

A study to be presented on Tuesday July 8 at the Goldschmidt conference in Prague suggests that hundreds of dormant underglacial volcanoes worldwide – especially in Antarctica – could become more active because climate change accelerates the retreat of glaciers.

The link between retired glaciers and the increase in volcanic activity has been known in Iceland since the 1970s, but this is one of the first studies to explore the phenomenon in continental volcanic systems. The results could help scientists better understand and predict volcanic activity in the regions covered with glacier.

Researchers from the University of Wisconsin-Madison, United States, used the dating of Argon and the analysis of crystals in six volcanoes in southern Chile, including the Mocho-Choshuenco volcano now sleeping, to study how Patagonian’s advance and retreat influenced volcanic behavior. Work is in collaboration with researchers from the University of Lehigh, the University of California Los Angeles and Dickinson College.

By precisely leaving the previous eruptions and analyzing the crystals in exploded rocks, the team followed how the weight and pressure of the ice ice modify the characteristics of the magma underground.

They found that during the summit of the last glacial period (around 26,000 to 18,000 years ago), thick ice cover removed the volume of eruptions and allowed a large magma reservoir rich in silica to accumulate 10 to 15 km below the surface.

While the glacial cap quickly founded at the end of the last ice age, the sudden weight loss made the crust and the gases in the magma expand. This pressure accumulation has triggered explosive volcanic eruptions from the deep tank, causing the formation of the volcano.

Pablo Moreno-Yaeger from the University of Wisconsin-Madison presents research at the Goldschmidt conference. He said: “The glaciers tend to remove the volume of the eruptions of volcanoes below. But as glaciers withdraw due to climate change, our results suggest that these volcanoes continue to burst more frequently and more explosively.

“The main requirement for increased explosiveness is initially a very thick glacial blanket on a magmatic chamber, and the trigger point is when these glaciers begin to withdraw, releasing the pressure – which currently occurs in places such as Antarctica.

“Our study suggests that this phenomenon is not limited to Iceland, where increased volcanity has been observed, but could also occur in Antarctica. Other continental regions, such as parts of North America, New Zealand and Russia, also deserve more in-depth scientific attention.”

Although the volcanic response to the glacial fusion is almost instant in geological terms, the process of changes in the magma system is progressive and occurs over the centuries, giving a little time for monitoring and early alert.

Researchers also note that an increase in volcanic activity could have global climatic impacts. In the short term, eruptions release aerosols (small particles in gases) which can temporarily cool the planet. This was observed after the 1991 eruption of Mount Pinatubo in the Philippines, which reduced global temperatures by around 0.5 ° C. But with multiple eruptions, the effects are reversed.

“Over time, the cumulative effect of multiple eruptions can contribute to long-term global warming due to an accumulation of greenhouse gases,” said Moreno-Yaeger. “This creates a positive feedback loop, where the melting of the glaciers triggers eruptions, and the eruptions could in turn contribute to additional warming and fusion.”