3D structure of the Campi Flegrei caldera central sector reconstructed through short-period magnetotelluric imaging.

The Campi Flegrei caldera experienced an unrest phase dating to 2005, which primary expression is the impressive ground uplift, accompanied by increasing degassing and seismic activities. Such last two phenomena developed mainly in the caldera central sector, including the Solfatara-Pisciarelli complex. However, the inner structure of such an area is still not defined, and this originates a poor understanding of the ongoing unrest. This paper describes the results of a new magnetotelluric survey performed in the Campi Flegrei caldera central sector. Through the inversion of data collected in 47 independent soundings, a 3D model of the electrical resistivity has been retrieved, which evidenced a partition of the investigated structure. The Agnano-Astroni area seems to be associated with a liquid-dominated geothermal reservoir, whereas the Solfatara-Pisciarelli area seems to be characterized by a single mixed liquid and gasses-dominated geothermal reservoir, which supplies the main caldera fumaroles. The proposed reconstruction of the geometrical characteristics of the hydrothermal system and the primary fluid rising pathways gives substantial clues about the significance of the detected structures in the evolution of the caldera unrest.

The Pisciarelli main fumarole mechanisms reconstructed by electrical resistivity and induced polarization imaging.

Pisciarelli, together with the adjacent Solfatara maar-diatreme, represents the most active structure of the Campi Flegrei caldera (Italy) in terms of degassing and seismic activity. This paper aims to define the structure of the Pisciarelli hydrothermal system (down to a 20 m depth) through electrical resistivity and time-domain-induced polarization tomography and self-potential mapping. The retrieved 3D image of the area helps reconstruct the Pisciarelli subsurface in its area of maximum degassing, containing the main fumarole ("soffione") and the mud pool. In particular, a channel has been identified in which fluids stored in a deeper reservoir rise toward the surface. Such a structure seems to be surmounted by a clay-cap formation that could govern the circulation of fluids and the abundance of gases/vapors emitted by the soffione. Based on this new reconstruction of the Pisciarelli fumarolic field structural setting, the first conceptual model has been suggested that is capable of simultaneously explaining the mechanisms governing soffione activity and elucidating the role played by the fluid/gas of deeper origin in the shallow fluid circulation system. The proposed model can potentially help to better monitor the processes occurring throughout the Pisciarelli fumarolic field and provide an evaluation of the associated hazards.

Publisher Correction: Deep Electrical Resistivity Tomography for a 3D picture of the most active sector of Campi Flegrei caldera.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Deep Electrical Resistivity Tomography for a 3D picture of the most active sector of Campi Flegrei caldera.

The central sector of the Campi Flegrei volcano, including the Solfatara maar and Pisciarelli fumarole field, is currently the most active area of the caldera as regards seismicity and gaseous emissions and it plays a significant role in the ongoing unrest. However, a general volcano-tectonic reconstruction of the entire sector is still missing. This work aims to depict, for the first time, the architecture of the area through the application of deep Electrical Resistivity Tomography. We reconstructed a three-dimensional resistivity model for the entire sector. Results provide useful elements to understand the present state of the system and the possible evolution of the volcanic activity and shed solid bases for any attempt to develop physical-mathematical models investigating the ongoing phenomena.

[Degree of hepatitis C infection risk in the health care setting]. / Entità del rischio infettivo per virus dell'epatite C in ambito sanitario.

BACKGROUND: Hepatitis C virus is the most important aetiologic agent for non A-non B hepatitis. The study of the prevalence of hepatitis C in health care workers is of primary interest because of the possible chronic evolution and the risk of cirrhosis and liver cancer. OBJECTIVES: The purpose of this study was to determine the prevalence of HCV among health care workers in 5 main hospitals and local health units in Turin and analyze the influence of occupational and non occupational risk factors. METHODS: Health care personnel were administered anonymous questionnaires and testing for anti-HCV antibody was performed. RESULTS: Prevalence rates in 4517 health care workers was 1.97%; the prevalence was higher in elderly workers (> 45 years) than in younger ones. The risk analysis did not reveal any significant correlation between HCV seroconversion and accidental blood exposure. However, a significant correlation was found with non-occupational risk factors. Unapparent infection was an unimportant risk factor for seroconversion. CONCLUSIONS: Hepatitis C prevalence in the population under study was comparable to that found in the general population. These results point to the need to reconsider the assumption that there is an increase of risk of seroconversion for health-care workers, in the absence of any occupational accidental exposure to hepatitis C virus.