M4.4 earthquake triggers seismic swarm at Italy’s Campi Flegrei caldera

A shallow magnitude 4.4 earthquake struck the Campi Flegrei caldera west of Naples, Italy, triggering a seismic swarm in the Gulf of Pozzuoli. The Italian National Institute of Geophysics and Volcanology (INGV) reported the quake occurred at a depth of approximately 3 kilometers and was the strongest in a sequence of 12 earthquakes that unfolded offshore between the Pozzuoli and Bacoli sectors. The main shock was widely felt across the Naples metropolitan area, prompting precautionary measures including school closures in the Bagnoli-Fuorigrotta “Red Zone” and inspections of public and private buildings. The seismic activity is part of an ongoing bradyseismic unrest at Campi Flegrei, a large volcanic caldera known for its ground deformation and frequent earthquake swarms. Since the onset of the current crisis, INGV has recorded around 23,000 earthquakes through 2024, underscoring the region’s heightened volcanic and seismic volatility. Campi Flegrei spans roughly 12 kilometers across and includes over 20 craters and volcanic structures, such as the Solfatara crater. Its geological history features two major explosive eruptions, including the Campanian Ignimbrite event approximately 39,000 years ago and the Neapolitan Yellow Tuff eruption about 15,000 years ago, with the most recent eruption forming Monte Nuovo in 1538. The caldera lies beneath one of Europe’s most densely populated volcanic regions, with about 3 million residents in the greater Naples area and several hundred thousand living within or adjacent to the caldera itself. This makes Campi Flegrei one of the world’s highest volcanic-risk urban environments. The recent seismic swarm highlights the ongoing need for vigilant monitoring and preparedness in the region, as the potential for volcanic activity poses significant risks to the local population and infrastructure. Authorities continue to assess the situation closely to mitigate hazards and ensure public safety.