Bradyseism in the Phlegraean Fields

The Phlegraean Fields are a vast active volcanic area affected by the phenomenon of "bradyseism": a ground deformation involving slow lowering (subsidence) phases alternating with more rapid uplift phases, the latter generally followed by shallow, low-magnitude earthquakes. 

A new uplift phase of the Phlegraean Fields caldera began in 2005 and is still ongoing. Since 2023, the frequency of earthquakes has gradually increased. In the same year, the strongest earthquakes occurred on September 27 and October 2, with magnitudes of 4.2 and 4.0, respectively. In 2024, the most significant event occurred on May 20, with a magnitude of 4.4, leading to the extraordinary mobilization of the National Civil Protection Service in support of the Campania Region. On May 30, 2024, a decree of the Minister for Civil Protection and Maritime Policies enabled the first rescue and aid operations for the affected population. The state of mobilization was declared ended on July 10 by a new decree of the Minister for Civil Protection and Maritime Policies.

As a response to the ongoing bradyseismic crisis, volcano monitoring activities were strengthened, and, more broadly, prevention efforts of the Civil Protection System have been intensified. In particular, Decree-Law No. 140 of October 12, 2023, provided urgent measures to prevent seismic risk related to the bradyseismic phenomenon in the Phlegraean Fields area.

On March 13, 2025, a significant earthquake registering a magnitude of 4.4 occurred during a seismic swarm. Following this event, the Campania Region requested an extraordinary state of mobilization for the National Service. In response, the Minister for Civil Protection and Maritime Policies issued a decree on March 13, 2025, to address the critical situation resulting from the seismic swarm.

Map of Rapid Emergency Planning in the Phlegraean Fields