A new study in collaboration between the University of Roma Tre and INGV just published on Communications Earth & Environment, shows that the seismicity of the Campi Flegrei is concentrating in a specific area of the crust: a sign of the formation or reactivation of a fault. This process explains the increase in bradyseism and indicates that the crust no longer responds purely elastically.
I Campi Flegrei They are an active volcanic caldera that, since the second half of 2005, has shown clear signs of disequilibrium: ground uplift, local shallow seismicity, and increased gas flows from fumarolic zones. This process, known as bradyseism, has intensified significantly since 2023, especially in the central area of the caldera between Pozzuoli and Bagnoli, with increasingly frequent and intense earthquakes. Several events have reached and exceeded magnitude (Md) 4, causing great concern among the population and localized damage.
A recent study, entitled Birth and growth of a volcanotectonic fault during the current volcanic unrest at Campi Flegrei caldera (Italy), published in the prestigious magazine Communications Earth & Environment from the publishing house Nature, has documented the transition - starting in 2023 - from widespread microseismicity throughout the caldera to a more concentrated distribution along a plane that can be interpreted as the nucleation or reactivation of a fault.
The research, the result of collaboration between the University of Roma Tre and the National Institute of Geophysics and Volcanology (INGV), provides an important contribution to the understanding of the seismic mechanisms at work.The observed phenomenon is fundamental to explain the localization and focal mechanisms of earthquakes. - explains Guido Giordano, full professor at the University of Roma Tre and coordinator of the research - and suggests that the crust's behavior has changed over time. This may have significant implications not only for strengthening monitoring, but also for defining the maximum expected magnitude.".
The study follows other independent research that had already highlighted a change in the relationship between seismicity frequency and uplift intensity; the new interpretation now offers a physical explanation linked to the formation of a fault.Our investigation – underlines Francesca Bianco, Research Director of the INGV - It benefited from a huge amount of high-quality experimental data, analyzed with innovative methodologies. Here too, the combination of monitoring and scientific research proved essential for gaining new insights into the processes underway at Campi Flegrei, providing potential clues. reading even for small-scale anomalies, such as those recorded in the Monte Olibano area".
In addition to Professor Giordano, Professor Francesco Salvini and Dr. Giada Alfonsi participated in the research for Roma Tre, while in addition to Dr. Bianco, Dr. Anna Tramelli, Dr. Mauro Di Vito, and Dr. Claudio Chiarabba participated for the INGV.
figure - Geographic distribution of earthquake epicenters detected by the INGV-Osservatorio Vesuviano seismic network between 2018 and 2024. Each image also shows the depth position of the earthquake hypocenters, seen along the north-south and east-west directions.
