Campi Flegrei: discovered a fragile layer in the earth’s crust that could explain the increase in bradisism and the intense seismic activity of the last few months.
In recent months, The Campi Flegrei have recorded an intense seismic activity and an increase in bradisism. In February 2025 there was a seismic swarm with beyond 1,800 earthquakesthe highest number of the last forty years, with shocks up to magnitude 3.9. March 13, a Earthquake of magnitude 4.4 He hit the area between Pozzuoli and Bagnoli, followed by other minor events. The soil lifting has reached a speed of about 30 mm per monthindicating an active phase of the phenomenon. Despite the intensification, the Ingv experts at the moment they exclude the risk of an imminent eruptionwhile maintaining constant monitoring of the situation.
The study. The phenomenon of bradisism and seismic shocks however is not new. We have always tried to understand what the causes of this phenomenon were. Now, a recent study by the National Institute of Geophysics and Volcanology (Ingv), published in the scientific journal AGU Advancesidentified A more fragile area than expected in the earth’s crust which would be at a depth between 3 and 4 kilometersthis could explain both the lifting of the soil, and the seismic activity which, periodically, affect the Phlegraean area.
The study, conducted as part of the Love-CF project (Long-Term Venting and Eruption at Campi Flegrei), financed by the Ingv, was born from a collaboration between the Ingv itself, the University of Grenoble Alpes and the University of Bologna. It is based on In -depth analysis of rocky champions extracted from a geothermal well about 3 kilometers deep. The researchers used advanced laboratory techniques and three -dimensional high resolution of the subsoil up to 4 kilometers to “reconstruct” what happens under our feet.
Between limestones and tuffs. Explains Lucia Pappalardo, Ingv researcher and co -author of the study: “We have identified an important transition to about 2.5–2.7 km of depth, where a weakening of the crustal layers is observed. Below this threshold, the crust appears more porous and permeable than expected, and therefore less resistant, favoring the accumulation of magmatic fluids». Francesco Maccaferri, Ingv researcher and co-author of the study adds: “The numerical simulations have shown that in past eruptive eras, numerous small intrusions of magma stopped in this area, where there is the transition from deep carbonate rocks and more superficial volcanic tuffs, helping to make it gradually weaker”.
According to Gianmarco Buono, lo weakened layer not only acts as a trap for deep magmatic fluidsbut it could also affect a possible future ascent of magma.
In the case of small volumes of magma, these tend to deviate their path and stop near the contact between a rigid, probably calcareous substrate, and overlying tuffs, cooling before reaching the surface in what is defined an aborted eruption process.
The way of a future eruption. However, if the accumulation of magma takes place more quickly, it may not have time to cool down and, after a phase of stasis at 3-4 km deep, resuming its ascent, as observed in the eruption of 1538, which led to the formation of Mount New.
This study, however, does not exclude that, in the event of a rise in major magma volumes with a deep tank (placed at about 7-8 km deep), the material can reach the surface directly, without crossing a phase of stasis in the weakened crusty layer-a mechanism that may have characterized some eruptions of past eras.
“This research does not directly affect our short-term forecasts, but it is a fundamental piece to understand the behavior of the volcano and improve our ability to monitor it”, underlines Mauro Antonio di Vito, director of the Vesuvian Observatory (Ingv-Ov). “Only with an increasingly detailed knowledge of the volcanic system and its dynamic can we hope to anticipate critical signals and reduce risks”.
