The Campi Flegrei caldera: unrest mechanisms and hazards

Abstract

In the last four decades, Campi Flegrei caldera has been the world's most active caldera characterized by intense unrest episodes involving huge ground deformation and seismicity, but, at the time of writing, has not culminated in an eruption. We present a careful review, with new analyses and interpretation, of all the data and recent research results. We deal with three main problems: the tentative reconstruction of the substructure; the modelling of unrest episodes to shed light on possible pre-eruptive scenarios; and the probabilistic estimation of the hazards from explosive pyroclastic products. The results show, for the first time at a volcano, that a very peculiar mechanism is generating episodes of unrest, involving mainly activation of the geothermal system from deeper magma reservoirs. The character and evolution of unrest episodes is strongly controlled by structural features, like the ring-fault system at the borders of the caldera collapse. The use of detailed volcanological, mathematical and statistical procedures also make it possible to obtain a detailed picture of eruptive hazards in the whole Neapolitan area. The complex behaviour of this caldera, involving interaction between magmatic and geothermal phenomena, sheds light on the dynamics of the most dangerous types of volcanoes in the world. et al. 2001), while the subsequent largest event, which generated the Neapolitan Yellow Tuff

Distributed-Temperature-Sensing Using Optical Methods: A First Application in the Offshore Area of Campi Flegrei Caldera (Southern Italy) for Volcano Monitoring

“…2016, 8,674 3 of 15 An improvement of the offshore geophysical monitoring will provide new data acquisition, which is crucial to obtain a more complete picture of caldera unrest mechanisms and of the caldera's extension in the submarine area. Finally, we highlight that fiber-optic sensing could potentially be the solution for the increasing demand to have reliable multi-parametric sensors (such as strain and temperature) since it provides remote sensing and high networking capabilities in the volcanic environment.…”

“…This sector is marked by the presence of minor, normal faults that subsided the apical dome possibly by diffuse pore fluid circulation along the higher permeability zones [24][25][26][27][28][29][30][31][32]. As regards the thermal state of the caldera, there is surface evidence of the presence of a high temperature geothermal system, which is mainly developed in the central part of the caldera at Solfatara crater [6][7][8][9][10][11]. This roughly corresponds to the zone of major collapse filled by volcano-clastic deposits of post-caldera volcanic activity, as testified by gravity anomalies and seismic and geological surveys [33,34].…”

High-resolution morpho-bathymetry of Pozzuoli Bay, southern Italy

“…Petrologic and geophysical evidence (e.g. Battaglia, Troise, Obrizzo, Pingue, & De Natale, 2006;Caliro, Chiodini, & Paonita, 2014;De Natale et al, 2006) suggest (for the Campi Flegrei caldera) the occurrence of a sill-like reservoir of fluids at a depth of 3 -4 km, associated with a deeper feeding magma reservoir located at a depth of ca. 8 km.…”

“…The Campi Flegrei district is an active volcanic area that covers about 200 km 2 of the coastal zone of SW Italy, a large part of which develops off the Gulf of Naples, and is characterized by at least one large caldera collapse structure. The caldera is represented by a quasi-circular area of 8 km in diameter in the central sector of the Campi Flegrei, including the Pozzuoli inland area and Pozzuoli Bay (Carlino & Somma, 2010;Dello Iacono, Zollo, Vassallo, Vanorio, & Judenherc, 2009;De Natale et al, 2006;Orsi, De Vita, & Di Vito, 1996;Rosi & Sbrana 1987;Sacchi et al, 2009;Scandone, Bellucci, Lirer, & Rolandi, 1991;Sacchi et al, 2014).…”

The Campi Flegrei deep drilling project (CFDDP): Caldera structure and hazard

“…In this case, deep drilling provides the best mean to obtain direct information on processes occurring at depth and represents a key tool for reconstructing the caldera structure and understanding the volcano dynamic and volcanic risk assessment [10]. The highly urbanised Campi Flegrei Caldera have been experiencing decades of unrest, with uplift rates up to 1 m/y, thousands of microearthquakes per year [11] and strong geochemical anomalies [12], leading to people evacuation of Pozzuoli town in [1982][1983]. At the present, the alert level for the caldera has been moved from 'base' (ordinary activity of volcano) to 'attention' status.…”