Magma transfer at Campi Flegrei caldera (Italy) before the 1538 AD eruption

Abstract

Calderas are collapse structures related to the emptying of magmatic reservoirs, often associated with large eruptions from long-lived magmatic systems. Understanding how magma is transferred from a magma reservoir to the surface before eruptions is a major challenge. Here we exploit the historical, archaeological and geological record of Campi Flegrei caldera to estimate the surface deformation preceding the Monte Nuovo eruption and investigate the shallow magma transfer. Our data suggest a progressive magma accumulation from ~1251 to 1536 in a 4.6 ± 0.9 km deep source below the caldera centre, and its transfer, between 1536 and 1538, to a 3.8 ± 0.6 km deep magmatic source ~4 km NW of the caldera centre, below Monte Nuovo; this peripheral source fed the eruption through a shallower source, 0.4 ± 0.3 km deep. This is the first reconstruction of pre-eruptive magma transfer at Campi Flegrei and corroborates the existence of a stationary oblate source, below the caldera centre, that has been feeding lateral eruptions for the last ~5 ka. Our results suggest: 1) repeated emplacement of magma through intrusions below the caldera centre; 2) occasional lateral transfer of magma feeding non-central eruptions within the caldera. Comparison with historical unrest at calderas worldwide suggests that this behavior is common.

A Physical Model of Sill Expansion to Explain the Dynamics of Unrest at Calderas with Application to Campi Flegrei

“…This result is in agreement with recent studies that highlight the important role of sill intrusions in the evolution of calderas and volcanic fields (Michaut and Jaupart, 2006;Rivalta, 2010;Corbi et al, 2015;Richardson et al, 2015;Di Vito et al, 2016;Le Mével et al, 2016;Papale et al, 2017). …”

Space‐weighted seismic attenuation mapping of the aseismic source of Campi Flegrei 1983–1984 unrest

“…Seismic attenuation tomography using coda‐normalized direct energies at Tenerife Island reveals that low‐attenuation anomalies are related to the position of potential ancient magma reservoirs [ Prudencio et al , ]. As shown by Di Vito et al [] using the historical, archeological, and geological record of Campi Flegrei caldera, progressive magma accumulation has been acting under the caldera center in a 4.6 ± 0.9 km deep source. This pattern is consistent with the deformation source shown in Figure b (18 Hz) [ Amoruso et al , ].…”

“…There is general disagreement regarding the nature (fluid, gaseous, or magmatic) of a 3–4 km deep high‐attenuation [ De Siena et al , ], high‐density [ Amoruso et al , ], low [ Vanorio et al , ] seismic volume located under Pozzuoli ( P , Figures a–c). This is the main source of deformation during past and recent unrests [ Battaglia et al , ; Amoruso et al , ; Woo and Kilburn , ; Amoruso et al , , ; Di Vito et al , ], producing ground uplift of ∼1.8 m during the 1983–1984 unrest [ Del Gaudio et al , ]. Nevertheless, scientists generally agree that a stable hydrothermal reservoir permeates the upper 3 km of the caldera, feeds on meteoric and deep magmatic sources, and responds to caldera unrests [e.g., De Siena et al , ; Chiodini et al , ; D'Auria et al , ; Petrillo et al , ].…”

An Approximate Approach to Nonisothermal Emplacement of Kilometer‐Sized Kilometer‐Deep Sills at Calderas

“…This seems to be hardly reconcilable with the emplacement of magmatic sills at low injection rates. In the case of Campi Flegrei multiple about‐equally‐large sill emplacements at low injection rates, like those possibly occurred in the last centuries (e.g., Amoruso et al, ; Amoruso, Crescentini, & Sabbetta, ; Amoruso et al, ; Bellucci et al, ; D'Auria et al, ; Di Vito et al, ), might have been permitted by a favorable thermal structure related to a flat kilometer‐sized relict thermal anomaly (Amoruso et al, ) dating from the last eruptive period (∼5.6 to ∼3.7 ka, e.g., Orsi et al, ). This last eruptive period was probably associated with high magma injection rates at about 3–4 km depth (e.g., Arienzo et al, ); magma temperature was ∼950 °C (Iovine et al, ; Masotta et al, ).…”