What could be more beautiful and relaxing than the lovely pine forests of Mount Etna? Views of deep green, the scents of earth and pine cones, shady paths… and a hidden enemy lying in wait in the heart of this paradise: the Pernicana Fault. Among the many faults crisscrossing the massive bulk of Mount Etna, this is perhaps the most insidious, the most “malicious”—if one can apply such a term to a natural feature that is simply doing what comes naturally! Should we fear the Pernicana Fault? Not necessarily. Here is its story.
Stories of “treacherous” earthquakes
The history of the Pernicana Fault is closely linked to the seismic history of Mount Etna. Over the centuries, numerous earthquakes have affected the volcano’s eastern and northern flanks. Earthquakes generated by this fault are almost always very shallow, meaning they can cause damage to the (few) buildings located along its path.
One of the most significant events associated with the fault occurred in 2002–2003, during one of Etna’s major recent eruptive crises. During that period, alongside volcanic activity, intense seismic activity occurred along several of the volcano’s tectonic structures. Notably, on October 29, 2002, an earthquake with a magnitude of around 4.4 struck the area of the Pernicana Fault. The quake damaged some buildings and highlighted the fault’s significance as a seismically active structure. The crisis continued over the following weeks, with numerous tremors of varying intensity. The event served as a prime example of the interplay between volcanic and tectonic activity.
Between 2018 and 2021, new technologies were tested along the fault; today, these allow for more precise monitoring of the fault’s movements and displacements, as detailed on the IL VULCANICO blog (Italian text only).
Pernicana: a fault “to monitor”
The Pernicana Fault is one of the major tectonic structures on the northeastern flank of Mount Etna. It is a particularly important fault for studying the volcano’s seismicity and evolution, as it cuts through an area heavily affected by fractures and ground movements. The fault extends for several kilometers across the northern and northeastern sectors of the Etna region, primarily affecting the area between the volcano’s higher elevations and the inhabited centers located on its slopes. Its name likely derives from the locality of Pernicana, near Linguaglossa. The structure is not a single, perfectly continuous fracture but rather consists of several segments that form a fault system.
Geologically, the Pernicana Fault primarily exhibits strike-slip movement—characterized by the horizontal sliding of large rock blocks—although vertical components may be present in certain sections. Its activity is closely linked to the complex deformation of Etna’s volcanic edifice. Indeed, the volcano is not a static structure; magma pressure, gravity, and tectonic forces continuously cause crustal deformation. Today, volcanologists use GPS instruments, geodetic stations, and other monitoring systems to measure crustal displacements. These instruments make it possible to determine whether different fault segments are accumulating deformation and to study the relationships between fault movements and those of the volcanic edifice.
The Pernicana escarpments
Another characteristic of the Pernicana route is the significant presence of escarpments and surface fractures, which bear witness to movements that have occurred over time. In some areas, the ground shows clear signs of deformation, such as displacements, fractures, and small morphological steps. These features serve as a sort of natural archive of the area’s tectonic activity.
Studying the Pernicana Fault is also crucial for civil protection efforts. Mount Etna is one of Europe’s most active volcanic and seismic zones, with numerous municipalities situated on its slopes. Understanding fault behavior allows for a better assessment of earthquake-related hazards and the development of monitoring systems and prevention strategies.
Not just an enemy to fight
It is important to note that studying faults does not allow us to predict exactly when an earthquake will occur. However, continuous monitoring makes it possible to detect changes in ground deformation and seismic activity, providing valuable information for understanding the area’s geological evolution.
Thus, the Pernicana Fault represents one of the most interesting elements of Mount Etna’s complex geological structure. Thanks to geological and seismic monitoring, we can now track its evolution and better understand the processes that continuously shape the landscape of Mount Etna.
The Pernicana Fault is not merely an enemy to be combated; it also holds surprises of great beauty. Indeed, just a short distance from the Rifugio Ragabo and Rifugio Brunek resorts in the territory of Linguaglossa lies the Piano Pernicana wood. Trails wind through the woods across flat terrain shaded by pine, oak, and chestnut trees, amidst which stand the tables and benches of a spacious picnic area. At Piano Pernicana, there also stands a delightful chapel dedicated to the Madonna, carved into the rock like an ancient cave; it features an altar and outdoor seating, allowing for ceremonies and masses to be held in the open air—a blend of Christian devotion and deeply pagan animist rituals dedicated to Mother Nature.