Photo: solar-system
Mount Etna is over half a million years old, yet this massive stratovolcano on Sicily remains highly active — and scientists have finally explained why.
Rising to about 3,400 meters, Etna is the most active volcano in Europe, erupting several times a year despite its age. It is known for producing alkaline lava, unlike most stratovolcanoes, and does so far more frequently than expected given the time usually required to form such magma.
For decades, researchers struggled to explain Etna’s behavior. Despite extensive studies and monitoring, no known geological process could fully account for how the volcano formed or where it continuously gets such large amounts of alkaline magma.
A new study by scientists from the University of Lausanne has uncovered important clues. They found that Etna is likely fed by a rare magmatic mechanism that was previously unknown and had only been associated with small underwater volcanoes.
The analysis suggests that Etna formed and operates differently from most volcanoes. Researchers believe it may be a unique geological system, where magma is released from a zone of low seismic wave velocity and transported to the surface in an unusual way.
These findings are important not only for volcanology but also for assessing risks associated with Etna, which lies near densely populated areas such as Catania and Messina.
Typically, volcanoes form when mantle material melts into magma and rises through the Earth’s crust. This usually happens in one of three ways:
- tectonic plates moving apart
- one plate sliding beneath another (subduction)
- hotspots formed by superheated mantle plumes
However, Etna does not fully fit any of these models. Although it sits above a subduction zone, the chemical composition of its lava resembles that of hotspot volcanoes — even though no known hotspot exists nearby.
By analyzing rock samples, scientists reconstructed the chemical profile of Etna’s lava over the past 500,000 years. Surprisingly, its composition has remained remarkably stable despite tectonic changes that would normally affect volcanic systems.
The data suggest that Etna does not rely on newly formed magma like most volcanoes. Instead, it likely draws from a slow, steady supply of pre-existing magma trapped between the upper mantle and the base of tectonic plates, about 80 kilometers below the surface.
Although alkaline magma typically forms slowly and in small quantities, Etna appears to access a unique reservoir. Researchers conclude that it may belong to a newly identified category of volcanoes (described in 2026), characterized by magma being extracted from mantle “pockets.”
This is unusual, as such systems are typically associated with small volcanic features — not massive structures like Etna.
