Mount Etna, an active stratovolcano on Sicily’s east coast, is one of the world’s most active volcanoes, with nearly continuous activity. Its presence significantly influences the Sicilian landscape and the lives of nearby residents. Its persistent volcanic activity has led to its designation as a UNESCO World Heritage Site and a Decade Volcano.
Understanding Mt. Etna’s Eruption Patterns
Eruptions have been documented for at least 2,700 years, with records stretching back to 1500 BCE. The volcano exhibits a variety of eruption styles, ranging from relatively mild effusive lava flows to more explosive events. These events can originate from its summit craters or from numerous vents along its flanks.
Eruptions from Etna’s summit craters are typically explosive but seldom pose a direct threat to nearby populated areas. In contrast, flank eruptions, which occur lower down the volcano’s slopes, can emerge closer to or within inhabited regions. Most of Etna’s eruptions are considered moderately small, frequently characterized by Strombolian activity.
The frequency of activity can be quite high, with the volcano sometimes erupting multiple times within a month or even a few weeks. For instance, in 2021, Mount Etna erupted 11 times in just three weeks, and it experienced two major eruptions in 2024 that temporarily closed Catania Airport. While many eruptions are minor, historical records detail more destructive events. The 1669 eruption, for example, destroyed at least ten villages and saw lava flows reach the city walls of Catania. Other significant events include the 1928 eruption that buried the village of Mascali and the 1971 eruption that destroyed the Etna Observatory and threatened several villages.
The Geological Engine Behind Mt. Etna’s Activity
Mount Etna’s frequent activity stems from its complex geological setting, positioned at the convergence of the African and Eurasian tectonic plates. The African Plate is in the process of subducting, or sliding beneath, the Eurasian Plate in this region. This ongoing interaction creates a zone where magma can rise to the surface, fueling the volcano.
The specific nature of Etna’s magma also contributes to its eruptive behavior. The volcano primarily produces basaltic magma, which is typically fluid due to its relatively low silica content. This fluidity allows magma to ascend more easily through crustal weaknesses and rifting processes, leading to frequent, often effusive, eruptions rather than highly explosive ones. While generally fluid, Etna’s magma can still generate explosive events, partly due to the presence of volatile gases and potential interaction with groundwater.
Scientists continue to investigate the precise mechanisms that supply magma to Etna, with theories suggesting a fault line between the African plate and a smaller Ionian microplate, or a “window” in the descending African plate allowing magma to rise from the mantle. This mantle-derived magma is often hotter and more fluid than magma typically found in subduction zones, which further explains the volcano’s characteristic frequent lava flows. This unique combination of a dynamic tectonic environment and fluid basaltic magma ensures Mount Etna remains a consistently active volcanic system.