The disappearance of ice could awaken dormant volcanoes, reveals a study conducted in the Chilean Andes. This phenomenon, long observed in Iceland, would now extend to other continents due to global warming.
Researchers have been studying the interactions between glaciers and volcanoes for decades. An international team analyzed six Chilean volcanoes, including Mocho-Choshuenco, to understand how melting ice influences their activity. Their results, presented at the Goldschmidt conference, suggest an increased risk of explosive eruptions in several regions of the world.
A pressurized mechanism
During the last ice age, a thick layer of ice compressed magma chambers, limiting eruptions. Crystalline analyses show that silica-rich magma accumulated between 6 and 9 miles (10-15 km) deep.
The rapid melting of ice 13,000 years ago released this pressure, causing violent eruptions. Expanding gases in the magma then fragmented the rock, generating powerful explosions. This scenario could repeat today in Antarctica, where about a hundred volcanoes are covered by ice.
Global consequences
In the short term, eruptions release climate-cooling aerosols. However, their repetition could accelerate warming through greenhouse gas emissions. Researchers describe a vicious cycle: melting ice triggers eruptions, which then worsen climate disruption.
Regions like Alaska or New Zealand, home to subglacial volcanoes, require increased monitoring. Isotopic data reveals these systems react with a delay of several centuries after melting, providing a window to anticipate risks.
Going further: How does ice suppress volcanoes?
The colossal weight of glaciers exerts constant pressure on the Earth's crust, like a lid on a pressure cooker. This compression prevents magma from rising to the surface and limits eruptions. Studies show a 4,900-foot (1,500 m) thick ice layer can halve volcanic activity.
When ice melts, this pressure drops abruptly, releasing forces contained in magma chambers. Dissolved gases like CO₂ and water vapor then expand, shattering rock into millions of particles. This mechanism explains why post-glacial eruptions are often more violent and ash-rich.
This phenomenon was observed in Iceland after the last ice age, with a 30-fold increase in eruptions. Today, Antarctica and other icy regions could follow the same scenario. Geochemical data reveals this process takes decades or even centuries, providing time to anticipate risks.
Article author: Cédric DEPOND