An earthquake swarm struck the Campi Flegrei area in southern Italy on June 30, 2025, with the strongest tremor recorded at a magnitude of 4.6. This quake, the most powerful in the region in four decades, surpassed earlier tremors of magnitudes 4.4 that occurred in March and May of the same year.
The epicenter of the earthquake was located near Bacoli, at a depth of 4 km (2.5 miles). The National Institute of Geophysics and Volcanology (INGV) noted that the event was part of a series of seven seismic occurrences. The quake struck around 12:47 local time (10:47 UTC), causing panic among residents in Naples, prompting evacuations, and leading to disruptions in train services throughout the region.
The Italian Civil Protection Agency confirmed that while there were evacuations and transport delays, initial checks indicated no significant damage to infrastructure. Schools, including the Righi Institute in the Fuorigrotta district, were evacuated in response to the tremors. Mayor of Pozzuoli, Luigi Manzon, emphasized the ongoing monitoring of the situation, confirming that no requests for assistance had been made by residents, although protocols for schools were activated.
Trenitalia, Italy’s state-owned railway operator, advised passengers to expect potential delays of up to 120 minutes or cancellations across various train services due to the earthquake’s impact.
Campi Flegrei is a highly populated area, housing over 500,000 residents, raising significant concern among civil protection authorities regarding volcanic or seismic activity. The region has witnessed a notable increase in seismic events, with two recent 4.4 magnitude earthquakes preceding the June 30 incident.
Interestingly, seismic swarms in the Campi Flegrei caldera have been linked to bradyseism, which involves vertical ground displacement due to the movement of underground magma or hydrothermal fluids. Recent studies suggest that managing groundwater extraction may alleviate some pressure in the reservoirs, potentially limiting seismic events.
Given the historical context of the region, which faced notable bradyseismic activities during the 1970s and 1980s that led to significant ground uplift and the evacuation of thousands, authorities remain vigilant as they navigate through this seismic swarm. With effective monitoring and intervention, there is hope that the impact of such events can be minimized for the safety of the residents.