On Monday evening, a 4.4 magnitude earthquake took place in Pozzuoli, city and comune of the Metropolitan City of Naples. The tremor was followed by at least 150 others in what authorities say is the most intense seismic activity in 40 years. Sitting next to the Campi Flegrei (Phlegraean Fields), a large volcanic caldera, emergency services are on standby in case of an eruption.
The Campi Flegrei is an active super volcano about 20 kilometres west of Naples, the largest of its kind in Europe. While scientists say an imminent eruption is unlikely, the build-up of magma and gases underneath the earth’s surface is causing the ground to rise and fall, a phenomenon called bradyseism. Bradyseism happens in 2 phases, a slower one, where the ground lowers, and a more rapid uplift phase, the latter being the cause of earthquakes.
A new uplift phase of the Phlegraean Fields caldera began in 2005 and is continuing. Since 2023, the frequency of earthquakes has gradually increased, peaking with Monday’s 4.4 tremor. Previously, the sequence had peaked with the September 27 and October 2 earthquakes, which had magnitudes of 4.2 and 4.0, respectively.
The Civil Protection Department is conducting inspections on public and private buildings to asses their integrity following the seismic activity. In Pozzuoli, 38 properties have been declared unfit for habitation following the earthquake, with hundreds of residents evacuated, while in Bacoli and Naples, evacuations have not yet started.
An €500 million budget has been allocated for wider evacuations, according to an emergency zone map, in the event of an eruption.
The red zone is an area at high risk for pyroclastic flows (hot, typically over 800 °C chaotic mixture of rock fragments, gas and ash), which are extremely dangerous due to their high temperatures and speed. In this zone, in case of “alarm”, preventive evacuation is the only protective measure for the population. Within the area there are approximately 500,000 residents. In case of an eruption, buses of the Campania Region will depart to drive citizens to meeting areas outside the red zone.
The yellow zone is the area exposed to significant volcanic ash fallout in case of eruption. This area may require temporary removals of the population living in vulnerable buildings or challenging to reach due to ash accumulation. In the area, there are over 800,000 residents. Some suburbs of Naples also lie in the red zone, including Chiaia and Vomero, while the of the city lies in the yellow zone.
While travelling to the region is considered safe, those going to the region are advised to follow local news and authorities’ updates on potential evacuations and safety zones. Meanwhile, the National Institute of Geophysics and Volcanology (INGV) has increased monitoring of the Campi Flegrei and installed a new multiparametric observatory for the study of the underwater hydrothermal degassing process of the caldera.
