The groundwater of the Caldera dei Campi Flegrei are the subject of a new studypublished in the magazine Journal of Volcanology and Geothermal Researchedited by a team of the Vesuvian Observatory of the National Institute of Geophysics and Volcanology (Ingv-Ov) in collaboration with various Italian universities. Research, entitled CHemical and Isotopic Characterization of Groundwater and Thermal Waters from the Campi Flegrei Caldera (Southern Italy), examined the chemical composition of subsoil waters, revealing considerable variability. The results made it possible to identify the processes of magmatic origin that influence its characteristics. The data collected are essential to improve the Monitoring networksallowing you to correctly interpret future changes in the chemical composition of the water and therefore identify any signals of recovery of volcanic activity.
The characteristics of the groundwater of the Flegrei fields
The study is the more exhaustive that has been conducted since 2005, when the current lifting phase of the Flegrei fields began due to the phenomenon of bradyseism. The researchers performed the analyzes on 114 samples of groundwateridentifying different types of water that coexist in the area. On the basis of the characteristics of the waters, the researchers were able to identify the processes that determine their composition. The latter is in fact conditioned by the interaction, within the aquifers, among the rocksthe circulating waters heated by magma and gas who get rid of it. These mechanisms depend in turn on chemical-physical factors that vary in space and time. The result is one great variety in composition underground waters, typical of volcanic areas. In the area of the Campi Flegrei, in particular, the presence of many faults and fractures facilitates the mixing between the superficial and deep underground waters, richer in gas and with greater salinity.
Under the caldera they are present cold waters of meteoric origin rich in bicarbonate, thermal waters originated from the interaction in depth with the gas of volcanic origin, chlorinated waters deriving from the mixing of rainwater and marine waters climbed by major depths, hot waters rich in sulphates characteristics of theSolfatara-Pisciarelli area. In this area the escape of gas and hot water from the ground is particularly intense, rather than in other areas of the caldera. Physical simulations suggest that intense episodes of magma dejugation, increasingly frequent in recent years, are the probable cause of the current lifting of the caldera.
What is the use of studying the groundwater of the Flegrei fields
“The work has made it possible to recognize the complex processes that control the different characteristics of the waters, including the addition of volcanic-hydrothermal gases and their dejections processes, contributing to the definition of the geochemical model of the system” explains Stefano Caliro, technologist manager Head of geochemical monitoring of the Campania volcanoes at the Ingv-Ov. This model will be fundamental for interpret any future changes in the chemistry of the groundwater of the Flegrei fields. These variations will be intercepted by one permanent monitoring network which will control different chemical-physical parameters of groundwater. The variations of these parameters could constitute precursor phenomena who promise the ascent of magma towards the surface.
