Publication Date:
2021-12-16
Description:
Phreatic and hydrothermal eruptions are small energetic explosive events that generally
have few to no precursors and represent a considerable hazard in tourist and urban areas. At the Campi
Flegrei caldera, these events have occurred at the Solfatara volcano and have likely occurred at the
nearby Pisciarelli site, where the most powerful hydrothermal phenomena are located. Here, increased
hydrothermal activity has caused relevant morphological changes that has led local authorities to deny
access to the site. Stratigraphic, structural, and geophysical investigations have allowed us to reconstruct
the volcano-tectonic setting of the area. In particular, we have recognized a fault system and related
damage zones that act as the preferred pathway for hydrothermal fluids in the caldera. At the surface,
these faults control the migration and/or accumulation of deep-seated gases into the subsoil and the
formation of fumaroles and mud pools. We have recognized two main fault systems with different ages
that show variable displacements. The electrical anomalies identified by electrical resistivity tomography
further highlight the main fault pattern and show the interplay between volcano-tectonic structures and
fluid circulation. Host rocks and fault zones may be involved in self-sealing processes and/or rock failure
phenomena capable of modifying the fluid pathways and establishing favorable conditions, leading
to overpressure and/or rapid decompression of fluids and triggering an explosive event. Furthermore,
stratigraphic mapping shows fossil mud pool sediments embedded in an old debris flow located above
the modern hydrothermal system. This implies that they were at a higher elevation when they formed.
The morphotectonic evolution and intense rock alterations in the area could promote further landslide
episodes, producing debris-flow deposits that can cover the active area and possibly trigger hydrothermal/
phreatic events.
Description:
Published
Description:
e2020TC006227
Description:
2V. Struttura e sistema di alimentazione dei vulcani
Description:
JCR Journal
Keywords:
fault system
;
hydrothermal fluids
;
geoelectrical image
;
volcanic hazard
;
04.08. Volcanology
;
04.02. Exploration geophysics
;
04.04. Geology
Repository Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Type:
article
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