Magma Transfer at Campi Flegrei Caldera (Italy) After the 1538 AD Eruption

Abstract

Shallow magma transfer is difficult to detect at poorly monitored volcanoes. Magma transfer before the last 1538 eruption at Campi Flegrei caldera (Italy) was exceptionally tracked using historical, archeological, and geological data. Here, we extend that data set to 1650 to uncover any magma transfer during post-eruptive subsidence. Results show two post-eruptive subsidence phases, separated by a previously undocumented uplift during 1540–1582. Uplift highlights the pressurization of the central (∼3.5 km depth) and peripheral (∼1 km depth) pre-eruptive sources, suggesting an aborted eruption. The subsidence events mainly require the depressurization of the central source and pressurization of a deeper magmatic layer (∼8 km depth). Therefore, despite the overall post-eruptive deflation, after 1538 the deeper reservoir experienced continuous magma supply, with magma almost erupting between 1540 and 1582, challenging the common assumption of post-eruptive deflation. This underlies the importance of monitoring the deeper magmatic systems, also after eruptions, to properly assess their eruptive potential.