The Deep Architecture of the Campi Flegrei Caldera (Italy) and Its Structural Control on Magmatic-Hydrothermal Processes as Revealed by 3D Multichannel Seismic Data
Abstract
The Campi Flegrei caldera (CFc) - situated in southern Italy at the border of the densely populated city of Naples - represents one of the world's highest volcanic risk areas as proven by its history of catastrophic eruptions, caldera resurgence, as well as recent volcanic unrest. Despite ample research in the last decades, the genesis of the CFc as well as its structural framework and eruption mechanisms remain strongly debated.
Here, we present the first 3D multichannel seismic dataset (25 m line spacing; 10-100 Hz) from a (partly) submerged caldera, providing the unique opportunity to image the entire caldera's architecture down to 2 km subsurface depth. Our data show clear evidence for the existence of a ~1 km deep caldera depression filled with ignimbrites and reworked volcanoclastic/sedimentary deposits, which is bordered by a ~2 km wide, arcuate ring-fracture zone. We propose that the ring-fracture zone represents an eruption site of the Campanian Ignimbrite (CI) leading to a coeval caldera collapse. As the location and style of the high-impact CI eruption remains strongly debated, this finding contributes significantly to our knowledge on the caldera's formation and associated eruption kinematics. Moreover, our data suggest that the ring-fracture zone has a strong control on the post-collapse ascent of hydrothermal fluids and magma as evidenced by the presence of intrusions, submarine vents, and shallow subsurface fluids. Hence, the caldera ring-fault zone depicts a key location for the interconnectivity between the surface and the deep magmatic-hydrothermal system. In fact, it may also play an important role during the recent unrest episodes e.g. by acting as stress-release pathways. Moreover, since the fracture zone has been prone to the rise of magma, it may represent a favourable site for future eruptions with crucial implications for the hazard and risk assessment. Overall, this study demonstrated the effectiveness of 3D seismic data in providing reliable constraints on the structural framework and magmatic-hydrothermal processes in (partly) submerged volcanic settings. Our work clearly showed that the submerged portion must be considered to be able to fully understand magmatic, hydrothermal, and volcanic processes at partly marine or lacustrine calderas.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.V13D0191S
- Keywords:
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- 1295 Integrations of techniques;
- GEODESY AND GRAVITY;
- 7280 Volcano seismology;
- SEISMOLOGY;
- 8178 Tectonics and magmatism;
- TECTONOPHYSICS;
- 8485 Remote sensing of volcanoes;
- VOLCANOLOGY