An international team of researchers has identified under the caldera dei Campi Flegrei a cavity Similar to a fracture, full of high pressure gases or fluids of magmatic origin. It is located under the area of Solfatara and Pisciarelli – then in the center of the volcanic caldera – to one depth of 3.6 kmit is about 1 km long and connects the deep magmatic tank to the origin of bradisism with surface fumaroles. This fracture has a particularity: for seven years “Rise” vibrating the passage of seismic waves of earthquakes that occur at the Flegrei camps. Discovery is important because this behavior helps better understand the internal structure of the Flegrei Campi and to detect its variations and those of the gases inside, which could indicate an increase in risk in the area. The study, published on Nature Communications Earth and Environmentis the result of a collaboration ofUniversity of Pisa with the National Institute of Geophysics and Volcanology (Ingv) and the GFZ Helmholtz Center for Geosciences of Potsdam.
The discovery of the fracture under the Flegrei fields
The fracture in the subsoil of the Campi Flegrei, never identified before, is found to 3.6 km deep under the Solfatara and Pisciarelli areawhere the lifting due to bradisism is maximum and the release of co2 From the ground in correspondence of the flues has increased considerably in recent years. The fracture is inclined, about 1 km long, 650 m widewith an average thickness of 35 cm and a total volume of about 220,000 m3. This structure, where they are accumulated high pressure gas or fluids of magmatic origin (This detail has not yet been clarified), connects the superficial smokes with the deep magmatic tank. The researchers discovered it and called it depth, orientation and geometry by analyzing beyond One hundred seismic events that occurred between 2018 and 2025. During these events, the fracture manifests the phenomenon of resonancethat is, it vibrates in response to the passage of seismic waves. In the seismic signal they are detected like this long -term oscillations (the period represents the time when a wave performs a complete oscillation) Vlp callswith a maximum duration of two minutes and a frequency of 0.114 Hz. According to the study, this happens at least since 2018 and to date the resonance frequency remained constant: this means that the geometry of the fracture and the characteristics of the gases that contains remained the same and that In the fracture the gas accumulates over time without being released.
The implications of the discovery
The fracture is at a depth in correspondence of which a recent study highlighted the presence of one weaker rocky layervery porous and therefore able to encourage the accumulation of fluids of magmatic origin, which when they increase in volume can cause soil deformation. These fluids, as well as those contained in the fracture, have difficulty leaking due to the presence of one rocky layer above waterproof. Consequently, under the Flegrei fields the pressure is gradually increasing and with it also seismicity and soil deformation rate. The resonance within the fracture full of fluids provides information on stress accumulated In the subsoil: the more often the resonance is activated, the greater the accumulated tension. This behavior was observed in other volcanoes, but at the Flegrei camps it was not never been documented first. The importance of the fracture is linked to the fact that it interacts both with a network of superficial faults and with the deep magmatic system, showing that the deep and more superficial layers of the system are behaving as one. Monitor the fracture is then particularly significant for the purposes of risk prevention Also because it is located below a densely inhabited area.
