The current crisis
A new uplift phase of the Phlegraean Fields caldera began in 2005 and is continuing. So far, as of November 2023, the maximum uplift achieved in the Rione Terra in Pozzuoli (the point of maximum deformation of the caldera) is about 118 cm, of which 85 cm since January 2016. From January to November 2023, the registered uplift is 17 cm.
Since 2018, this phenomenon has been followed by a gradual increase in seismic activity, the number of earthquakes, and their magnitude.
Seismicity. In 2023, while most events had low magnitudes (about 90% had magnitudes below 1.0), there was a new increase in the frequency of earthquakes. Most of the events occurred between Astroni, Solfatara-Pisciarelli-Agnano, Pozzuoli, and Gulf of Pozzuoli, with maximum depths of about 4 km, primarily concentrated in the first 2 km. The sequence peaked with the events of September 27 (Md 4.2) and October 2 (Md 4.0), located between Bagnoli and Pozzuoli and in the Pisciarelli-Solfatara area, respectively. No major magnitude events were recorded in the first months of 2024 compared with the two events in September and October 2023.
Comparison with the bradyseismic crisis of the 80's. The current situation is marked by ground uplifts and earthquakes of a magnitude comparable to those experienced in the bradyseismic crisis of 1982-84, while in terms of impact on buildings and infrastructure, the picture is very different. The crisis of the 1980s produced extensive damage to buildings, especially in the municipality of Pozzuoli, enough to require the evacuation of the population from their homes in the historic center, just as it happened during the bradyseismic crisis of the 1970s for the inhabitants of the Rione Terra.
The current bradyseismic crisis has not caused substantial significant damage so far. The reasons are to be found in the different vulnerabilities of the buildings and the different evolution of the phenomenon in the frequency of quakes and the rate of uplift. Most of the structures in the area today consist of buildings not exceeding three stories, mostly made of reinforced concrete or masonry, which have undergone seismic retrofitting interventions since the 80's. To this end, with the Ministerial Decree issued by the Ministry of Public Works on March 7, 1981, the municipalities in the Phlegraean area were classified as seismic with the mandatory observance of technical regulations for construction.
Initial response to the crisis. The recent escalation of the bradyseismic crisis, culminating in September and October 2023 events, required the strengthening of volcano monitoring activities by Ingv and other Centers of Expertise and, more generally, a tightening of preventive measures by the Civil Protection System.
The opinion of the National Major Risks Commission. In the last months of 2023, the Department has called the National Major Risks Commission - Volcanic and Seismic Risk Sector several times to know its opinion on the current situation and to perform further analysis and investigations, given the complex nature of the issue and the potential evolution of the volcano's dynamics. Several national and international experts were also involved to have further assessment elements.
As a result of these meetings, the Commission found that the scientific findings reinforce the evidence for the presence of deep-seated magma as the root cause of the current bradyseismic crisis. However, without evidence of rising magma, it was concluded to confirm "the yellow alert level for volcanic risk." Therefore, the Commission believes that monitoring activities by the Centers of Expertise and prevention activities by the various components of the National Service should be further strengthened and prepared for the potential need to increase the alert level.
The issuance of the decree-law. Simultaneously, to provide an organic response to the effects of the ongoing bradyseismic crisis with both structural and nonstructural prevention measures, the government approved Decree-Law No. 140 of October 12, 2023, "Urgent measures for the prevention of seismic risk related to the bradyseism phenomenon in the Phlegraean Fields area," which was subsequently converted into Law No. 183 of December 7, 2023. The decree defines the main actions the Civil Protection System must implement to effectively respond to a complex risk situation such as the one in the Phlegraean Fields area.