Through high-resolution geoelectrical surveys, the surface structure of the subsoil of the Pisciarelli area, the area of greatest fumarolic and hydrothermal emission of Campi Flegrei, was defined in 3D.
Electrical geophysical investigations have allowed the creation of a new 3D image of the most superficial part of the Pisciarelli hydrothermal system.
Using high-resolution tomographic techniques, a team of researchers from the Vesuvius Observatory of the National Institute of Geophysics and Volcanology (OV-INGV) has reconstructed the structure of the subsoil in the area of maximum gas emission of the Campi Flegrei volcano.
The results of the study "The Pisciarelli main fumarole mechanisms reconstructed by electrical resistivity and induced polarization imaging”, carried out within the INGV 'Dynamic Planet - Working Earth' project and the INGV-DPC 2-2019 B2021 Convention, have just been published in the journal 'Scientific Reports'.
The fumarolic field of Pisciarelli and the nearby Solfatara currently represent the most active volcanic sector of the Campi Flegrei caldera both for the flow of gaseous emissions and for the most recent seismic activity.
In the last decade, the Pisciarelli area has shown considerable morphological changes witnessed by the opening of new fumarolic vents, by variations in the geochemical characteristics of the fluids and by some episodes of mud emission. As a result, access to the area has long since been closed to the public for safety reasons.
"We carried out high-resolution tomographic surveys”, explains Antonio Troiano, researcher at the INGV Vesuvius Observatory and first author of the research. "From the 3D model obtained from these new geoelectric investigations, we were able to reconstruct the structure of the subsoil in the area of maximum gas emission, containing the main fumarole (so-called "head") and the mud puddle which, over time, has changed and expanded".
"In this research”, specifies Roberto Isaia, researcher at the INGV Vesuvius Observatory, “we have shown that the main way of ascent of the fluids takes place from a deeper reservoir through a conduit, in the upper part of which there is a formation of clayey material. The geometry of the structures surveyed provides fundamental information to clarify the processes that regulate the circulation of fluids and the emission of gases or vapors in the area under examination".
"Thanks to the high sensitivity of the resistivity and the electrical chargeability in detecting the presence of fluids inside the buried structures”, continues Antonio Troiano, "it was possible to create the first conceptual model capable of explaining the mechanisms governing the emission activity of the Pisciarelli complex".
The 3D image of Pisciarelli and the proposed model represent a significant scientific contribution to understand the evolution of the volcanic phenomena taking place in the area, to evaluate the associated risks and to improve the monitoring strategies of this fumarolic field.
A contribution that could be useful in the future to refine the forecasting and prevention tools of civil protection but which at the moment has no direct implication on measures concerning the safety of the population.
link:
---
A new 3D model of the subsoil of an area of Campi Flegrei
Through high-resolution geoelectrical surveys, the shallow structure of the subsoil of the Pisciarelli area, the fumarolic field with most intense hydrothermal emission of the Campi Felgrei caldera, was defined in 3D.
Electrical geophysical investigations have allowed the reconstruction of a new 3D image of the most shallower part of the hydrothermal system of Pisciarelli.
Using high-resolution tomographic techniques, a team of researchers from the Vesuvius Observatory of the National Institute of Geophysics and Volcanology (OV-INGV) reconstructed the structure of the subsoil in the area of maximum gas emission of the Campi Flegrei volcano.
The results of the study "The Pisciarelli main fumarole mechanisms reconstructed by electrical resistivity and induced polarization imaging", supported by the INGV Project 'Pianeta Dinamico - Working Earth' and the B2 INGV-DPC 2019-2021 Convention, have just been published in 'Scientific Reports' journal.
The fumarolic field of Pisciarelli and the nearby Solfatara currently represent the most active volcanic sector of the Campi Flegrei caldera both for emissions and more recent seismic activity.
In the last decade, the Pisciarelli area has shown significant morphological changes including the opening of new fumarolic vents, variations in the geochemical characteristics of the fluids and some episodes of mud emissions. As a result, access to the area has long been forbidden to the public for safety reasons.
"We carried out high-resolution tomographic survey", explains Antonio Troiano, researcher at Osservatorio Vesuvano, INGV, and first author of the study. "From the 3D model obtained from these new geoelectric investigations, we were able to reconstruct the structure of the subsoil in the area of maximum degassing, containing the main fumarole (so-called "Soffione") and the mud pool which, over time, has changed and expanded".
"In this research", explains Roberto Isaia, researcher of the Vesuvius Observatory, INGV, "we have highlighted that the main way of uprising fluids occurs from a deeper reservoir through a channel, surmounted by a clay-cap formation. The geometry of the detected structures provides fundamental information to clarify the processes that regulate the shallow fluids circulation and the emission of gases or vapors in the study area".
"Thanks to the high sensitivity of resistivity and electrical chargeability in detecting the presence of fluids inside buried structures", continues Antonio Troiano, "it was possible to create the first conceptual model capable of explaining the mechanisms that govern the activity emission of the Pisciarelli complex ".
The new 3D image of Pisciarelli and the related conceptual model can help to understand the evolution of volcanic phenomena taking place in the area, to provide an evaluation of the associated hazards, and to better monitor the processes occurring in the Pisciarelli fumarolic field.
A contribution that may be useful in the future to refine the tools for forecasting and prevention of civil protection but which at the moment has no direct implication on measures concerning the safety of the population.
link:
Fig. 1 – Graphical representation of the 3D model obtained by electrical resistivity tomography.
Fig.1 - Sketches of the 3D resistivity model.
Fig. 2 - Map of the Phlegraean caldera. The black rectangle highlights the position of the Pisciarelli fumarolic field, site of the geophysical investigations.
Fig 2 - Map of the Campi Flegrei caldera. The black box outlines the location of the PFF site.
Fig. 3 - Structural model of Pisciarelli's fumarolic field.
Fig.3 - Structural setting of the PFF feeding system.