Located in Sicily, Mount Etna is Europe’s most active volcano. Yet its origin remains largely enigmatic, as no existing geological model fully explains how it formed. In a new study, scientists from the University of Lausanne (UNIL) shed light on these mechanisms and reveal why Mount Etna may in fact be unique in the world.
More than 500,000 years old and rising over 3,000 metres above sea level on Sicily’s eastern coast, Mount Etna erupts several times a year, making it both the most active and one of the most closely monitored volcanoes in the world. Despite this, its origin remains partly mysterious: no known geological process fully accounts for the formation of this giant.
In a new study published in the Journal of Geophysical Research – Solid Earth , scientists from the University of Lausanne (Unil), in collaboration with Anna Rosa Corsaro, a researcher from the Istituto Nazionale di Geofisica e Vulcanologia in Catania, unveil a new hypothesis that could transform our understanding of how Mount Etna formed. Their findings shed new light on the volcano’s unusually frequent eruptions and pave the way for improved volcanic hazard assessment by researchers at INGV in Catania, Italy.
Why Etna Doesn’t Fit Any Category
Volcanoes on our planet form when part of the Earth’s mantle melts into magma, rises to the surface, and solidifies. Until now, it was thought that volcanoes form according to three main mechanisms:
Mount Etna, however, fits into none of these categories. Located near a subduction zone, its chemical composition resembles that of hotspot volcanoes, even though no hotspot is present nearby. The new study shows that, unlike conventional volcanoes—where magma forms shortly before an eruption—Etna is fed by small amounts of magma already present in the upper mantle, some 80 kilometers beneath the surface. These magmas are transported sporadically toward the surface by the complex tectonic movements resulting from the collision between the African and Eurasian plates. The magma rises through fractures in the tectonic plate created as it bends near the subduction zone, much like liquid being squeezed from a sponge.
The Sicilian volcano may therefore belong to a little-known fourth category of volcanoes: so-called “petit-spot” volcanoes, first described in 2006 by Japanese geologists. These tiny submarine volcanoes provide compelling evidence for the existence of pockets of magma at the top of the Earth’s mantle—an idea first proposed in the 1960s—and show that, under certain conditions, such magmas can give rise to volcanoes.
“Our study suggests that Etna may have formed through a mechanism similar to the one that generates petit-spot submarine volcanoes,” explains Sébastien Pilet, Professor at the Faculty of Geosciences and Environment at the University of Lausanne and lead author of the study. “This is unexpected, as such processes had previously only been observed in very small volcanic structures, typically rising no more than a few hundred metres. Mount Etna, by contrast, is a large stratovolcano, whose activity began around 500,000 years ago and which now towers more than 3,000 metres above sea level.”
This discovery opens up new perspectives for understanding how other volcanic systems may form around the world.
Methodology
Scientists collected samples from Mount Etna to reconstruct the chemical evolution of the lavas erupted since the volcano formed, approximately 500,000 years ago, up to the present day. Based on experimental data, they were able to show that the composition of Etna’s magmas has remained largely consistent over time, even as the tectonic regime evolved. These combined observations support the idea that the magmas feeding Etna pre-exist in the upper mantle, and that variations in erupted volumes are primarily controlled by plate movements. This interpretation links Mount Etna’s volcanism to the “petit-spot” mechanism.
Source : S. Pilet, J. Reymond, L. Rochat, R. A. Corsaro, M. Chiaradia, L. Caricchi, O. Müntener, Mount Etna as a leaking pipe of magmas from the low velocity zone , Journal of Geophysical Research - Solid Earth, 2026
Journal of Geophysical Research Solid Earth
Mount Etna as a leaking pipe of magmas from the low velocity zone
7-Apr-2026