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

Trasatti, Elisa; Magri, Carmine; Acocella, Valerio; Del Gaudio, Carlo; Ricco, Ciro; Di Vito, Mauro A.

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. Plain Language Summary: Today, volcanic activity is monitored by satellite and ground networks. However, very little is known about the pre‐ and post‐eruptive behavior of volcanoes before the instrumental era. Here, we present a unique set of archeological records related to the elevation changes at Campi Flegrei caldera (Italy) during 1515–1650, mainly focusing on its behavior after the last 1538 eruption at Monte Nuovo. After the eruption, subsidence occurred from 1538 to 1540, followed, from 1540 to 1582, by a previously unreported uplift; the latter was followed by renewed subsidence until 1650 at least. Modeling the sources responsible for the deformation, we find that, despite the depressurization of shallow sources, after 1538, a deeper magmatic layer (∼8 km depth) experienced continuous magma supply, with magma almost erupting between 1540 and 1582. This questions the common notion of post‐1538 deflation at Campi Flegrei, where the depressurization of the shallower sources masks the pressurization of the deeper magmatic system for more than a century. Key Points: 20 archeological sites at Campi Flegrei show two post‐1538 eruption subsidence phases, separated by an undocumented uplift in 1540–1582During 1540–1582, a central sill‐like source (∼3.5 km depth) transfers magma below Monte Nuovo, representing an aborted eruptionFrom 1538 to 1650 a deeper magmatic layer (∼8 km depth) experienced continuous magma supply, also during caldera subsidence

MAGMAS; CALDERAS; VOLCANIC eruptions; LAND subsidence; VOLCANOES

Geophysical Research Letters, 2023, Vol 50, Issue 11, p1

0094-8276

Academic Journal

10.1029/2022GL102437