New research on Europe's most closely monitored volcano published in AGU Advances
A recent study byNational Institute of Geophysics and Volcanology (INGV), published in the scientific journal AGU Advances, has identified a more fragile than expected zone in the Earth's crust beneath the caldera of Campi Flegrei, one of the most active and complex volcanic areas in Europe.
According to the researchers, this weak layer It is located at a depth of between 3 and 4 kilometers and could explain phenomena such as the uplift of the ground and the seismic activity that periodically affect the Phlegraean area.
The study, conducted within the framework of the LOVE CF project () funded by INGV, was born from a collaboration between theINGV, University of Grenoble Alpes e University of Bologna, and is based on in-depth analysis of rock samples extracted from a geothermal well about 3 km deep. The researchers used advanced laboratory techniques and high-resolution three-dimensional images of the subsurface up to 4 km to "observe" what is happening beneath our feet.
"We have identified an important transition at about 2,5–2,7 km 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", explains Lucia Pappalardo, INGV researcher and co-author of the study. “These fluids, trapped, progressively increase in volume and pressure, triggering ground deformations and seismic activity”.
“Numerical simulations have shown that in past eruptive periods, numerous small magma intrusions stopped right in this area, at the transition between the deep carbonate rocks and the more superficial volcanic tuffs, contributing to making it progressively weaker”, he adds Francis Maccaferri, INGV researcher and co-author of the study.
“This weakened layer not only acts as a trap for deep magmatic fluids, but could also condition any future magma ascent”, he specifies Gianmarco Good, INGV researcher and co-author of the study.
In the case of small volumes of magma, these tend to deviate their path and stop near the contact between a rigid substrate, probably calcareous, and the overlying tuffs, cooling before reaching the surface in what is defined as an aborted eruption process. However, if the accumulation of magma occurs more rapidly, it may not have time to cool and, after a phase of stasis at 3-4 km depth, resume its ascent, as observed in the last eruption of the Campi Flegrei in 1538, which led to the formation of Monte Nuovo.
This study, however, does not exclude the possibility that, in the case of the ascent of larger volumes of magma from the deep reservoir (located at about 7-8 km depth), the magma could reach the surface directly, without going through a stasis phase in the weakened crustal layer - a mechanism that could have characterized some eruptions in past eras.
“This research does not directly influence our short-term forecasts, but it is a fundamental piece in understanding the volcano's behavior and improving our ability to monitor it.”, points out Mauro Antonio DiVito, Director of the Vesuvius Observatory (INGV-OV). “Only with an increasingly detailed knowledge of the volcanic system and its dynamics can we hope to anticipate critical signals and reduce risks for people”.
The discovery confirms how important it is to continue to study the Campi Flegrei system in depth and to maintain a high level of attention through continuous and multidisciplinary monitoring.
The article was chosen to be advertised on EOS.org, a recognition of the important scientific content of the publication: .
Image - This model illustrates the structure of the Earth's crust in the Campi Flegrei area, divided into three main domains, defined thanks to the analysis of geothermal well samples and seismic tomography data. It also shows the density map of magmatic intrusions, obtained through simulations (represented with shaded colors), and the distribution of earthquakes that occurred between 2000 and 2025. Earthquakes with a magnitude greater than 3 are concentrated above the weak layer most intensely crossed in the geological history of the caldera by magmatic dikes, at a depth of between 2 and 3 kilometers.