An earthquake swarm with the strongest quake registered as an M4.6 quake struck the Campi Flegrei area in southern Italy on June 30, 2025, prompting evacuations and train delays in the region. It was the strongest tremor to strike the region in 40 years, surpassing the M4.4 quakes of March and May.

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A new earthquake swarm began in the Campi Flegrei caldera at 14:23 local time on May 14, 2025, just five hours after Italy’s National Institute of Geophysics and Volcanology (INGV) reported the end of a previous swarm that led to a state of emergency declaration.

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A state of emergency was declared for Italy’s Campi Flegrei area on May 13, 2025, following an M4.4 earthquake within a swarm of earthquakes that produced 49 registered events. The swarm began at 12:06 LT on May 13 and ended during the morning hours of May 14, according to the INGV Vesuvian Observatory. The Campi Flegrei caldera is one of Europe's most closely monitored volcanic areas due to its dense population and history of significant unrest.

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