It happens often—all too often, in fact—that tourists or hikers visiting our volcano encounter prohibitions that prevent them from ascending toward the craters. For visitors, these restrictions become a nuisance, a source of frustration, and a trigger for complaints. “What do you mean? I’m only here for a few days, and you won’t let me go up?” Or perhaps a local resident complains because it was their only day off work, and now they have to cancel their excursion! Arguments immediately erupt on social media, directed against the Regional Etna Park authorities, government officials, and even the volcanologists themselves. But, ladies and gentlemen, the summit of Etna is not an amusement park. When it is closed, there is always a reason!
What Etna Was Like
Mount Etna, located on the eastern coast of Sicily, is one of the most active volcanoes in Europe. Its eruptive activity has been documented since ancient times and has profoundly influenced the history and culture of the local population.
One of the earliest known eruptions dates back to 475 BC, when the volcano produced significant lava flows. Over the centuries, Etna has continued to erupt frequently. Among the most dramatic episodes was the eruption of 1669, during which a massive lava flow reached the city of Catania, destroying numerous buildings and altering the landscape. Another particularly violent eruption occurred in 1928, when lava partially destroyed the town of Mascali.
Interestingly, for thousands of years, Etna had only a single crater at its summit. That crater typically produced eruptions characterized by long lava flows, few explosions, and only rare, violent events. A “quiet” volcano for most of its existence—so much so that it has been nicknamed the “good volcano.” Locals even call it “Mother Etna,” as its eruptions have created fertile soil through the deposition of volcanic ash. Over the last three centuries, Etna has also become a remarkable driver of tourism. For these reasons, the volcano is considered a precious resource for the region and for the lives of those who inhabit it. And yet…
How it is changing
In modern times, Etna has shown a notable trend for a change. Since 1911, its summit has effectively split apart, giving rise to four distinct summit craters. Throughout the 20th century, there were also numerous flank eruptions, with lava flows even overwhelming several settlements (such as Mascali in 1928, Fornazzo in 1971, and Randazzo in 1981). Between 1991 and 1993, a prolonged eruption threatened the town of Zafferana Etnea. Later, in 2002–2003, powerful explosions and lava flows caused damage to tourism infrastructure.
Today, Etna is known precisely for its frequent explosive eruptions—a phenomenon referred to as Strombolian activity or paroxysms. During these events, the summit craters eject lapilli, ash, and fragments of incandescent lava into the air. In some instances, true “lava fountains” form, reaching significant heights and creating spectacular light displays visible from great distances. While lava flows still occur, they are now frequently accompanied by more intense and regular explosive activity. Another significant difference compared to the past concerns monitoring. Today, Mount Etna is under constant surveillance through seismic instruments, satellites, and scientific observation. This makes it possible to detect changes in volcanic activity and alert the population in the event of danger.
Volcanologists based in Catania—experts with few peers anywhere in the world—confirm that the volcano’s “behavior” has changed. And, as it remains in a transitional phase, it is more unpredictable than ever. What is particularly alarming are the pyroclastic flows—phenomena that have suddenly become quite common on Etna!
The danger of Pyroclastic Flows
Pyroclastic flows are highly dangerous volcanic phenomena consisting of a mixture of gas, ash, rock fragments, and incandescent volcanic material that moves rapidly down the flanks of a volcano. They can reach extremely high temperatures and speeds of hundreds of kilometers per hour, making them one of the primary threats associated with volcanic eruptions. The most famous instance is the one that destroyed Pompeii in 79 AD.
Unlike lava flows, which generally move more slowly, pyroclastic flows can travel at great speed, destroying everything in their path. On Mount Etna—one of Europe’s most active volcanoes—such phenomena do occur, though they have never before appeared with the frequency seen today.
On Etna, these flows tend to occur primarily during particularly intense eruptions. While the volcano’s activity is predominantly effusive—characterized by the outflow of lava—it can also produce explosive episodes. During an explosive eruption, a large volume of gas dissolved within the magma is released rapidly, causing the volcanic material to fragment and forming a scorching cloud of gas and particles. Pyroclastic flows can also form when a portion of an eruptive column—the cloud of gas and material rising above the crater—becomes too heavy and collapses toward the ground. Another possible mechanism is the collapse of unstable sections of the volcano’s cone or flanks, which can trigger an avalanche of hot material.
In the case of Mount Etna, the combination of increased eruptive power and the fragility of its summit has recently led to an excessive number of these searing flows. Given that excursions into the Valle del Bove (at the foot of the craters) are very popular among tourists, pyroclastic flows—though not the most frequent phenomenon on Mount Etna—are monitored with great care.
When a prohibition is in place, there is always a good reason for it
There is a highly advanced analysis and alert system, powered by artificial intelligence—which we will discuss in greater detail in another article—that makes it possible to anticipate the risk of pyroclastic flows. While the specific event itself can never be predicted—it is impossible to know exactly when or how one might form—it is possible to determine that the conditions for their formation exist. It is on this basis that decisions are made to close off access to the Valle del Bove or the summit. If such a prohibition is in place, there is always a valid reason for it. So, please respect it!