A new study reveals the groundwater system of the Flegrei fields

“The work represents the first exhaustive study on the geochimic of the Flegrea flap since 2005 the start of the current braiseismic crisis EL, and has made it possible to recognize the complex processes that control the different characteristics of the waters, including the addition of volcanic gases- hydrothermal and their dejection processes, contributing to the definition of the geochemical model of the system” explains Stefano Caliro, technologist manager responsible for the geochimic monitoring of the Campania volcanoes at the Ingv-Ovunderlining how the understanding of these processes is crucial for monitoring volcanic activity.

Map of the temperature of the underground water of the caldera. In the areas of Solfatara-Pisciarelli and Baia Mofete Monte Nuovo are evident the two main thermal anomalies. The symbols and their dimensions identify the different characteristics and temperatures of the water.

“Among the most interesting results there is the integration of the conceptual model with the numerical physical model of the system, which provides for a rise of gas in the Solfatara-Pisciarelli area, and identify the interaction between volcanic fluids and aquifers based on the characteristics of the waters. This area is confirmed as the heart of the hydrothermal activity of the Caldera“, he underlines Giovanni Chiodini, research manager associated with the INGV.

The identified geochemical processes are closely connected, but each dominates in specific regions of the hydrothermal systemtherefore causing the great variability in the composition of the groundwater inside the caldera. In the Flegrei camps, in fact, cold waters of meteoric origin, thermal baking soda water originated from the interaction with gases in the peripheral areas of the system, chlorinated waters derived from saline solutions at high temperature, and, finally, groundwater of the Solfatara-Pisciarelli area , where the condensation of sulfur rich steam plays a decisive role.

“The investigation therefore aimed to better understand the chemical processes that influence the composition of the underground waters. Through the analysis of 114 samples collected in an extensive campaign of measures between 2013 and 2014, we have developed a geochemical model that has made it possible to describe the evolution of the interaction of rainwater with hydrothermal saline solutions and volcanic gases during his underground route“, he adds Alessandro Aiuppa, professor at the University of Palermo.

Conceptual model of distribution of the different types of underground water water, compared with the physical model of the geothermal system of the Flegrei Campi. In the background the characteristics of the geological section of the Caldera.

The collected data therefore allowed to develop An advanced conceptual model useful for highlighting and interpreting any future changes in the chemistry of groundwater and in the dynamics of processes. “The results of this study made it possible to design and create a permanent multiparametric network of water monitoring in the caldera, active from 2018 and in constant evolution, which represents an essential tool for detecting changes in the system and recognizing any signs of the resumption of volcanic activity“, conclude Mauro A. Di Vito, director of the Ingv-Ov.