Magmatic overpressure and reservoir rupture conditions of the Nisida eruption (3.98 ka): implications for magma-driven unrests at Campi Flegrei caldera
Jacopo Natale 1, Stefano Vitale2
Affiliations: 1 Department of Earth and Geoenvironmental Sciences, University of Bari \"Aldo Moro\", Italy; 2 Department of Earth, Environmental and Resources Sciences, University of Naples \"Federico II\", Italy
Presentation type: Poster
Presentation time: Thursday 16:30 - 18:30, Room Poster Hall
Poster Board Number: 193
Programme No: 1.8.24
Abstract
Volcanic eruptions occur when magma-filled fractures break through the Earth's crust reaching the surface. Reconstructing the geometry of feeder dykes can provide insights into physical parameters such as overpressure and inform about reservoir rupture conditions, which are pivotal for volcano monitoring purposes. This is extremely relevant in highly urbanized volcanic areas such as the Campi Flegrei caldera (southern Italy), which experienced several volcanic unrest in the last decades. This work focuses on the low-moderate magnitude Nisida fissure eruption (3.98 ka), which precedes the only historical eruption in 1538 CE. We combined new structural evidence associated with dyke-induced deformation with existing petrological, geochemical and geophysical data. Based on suitable crustal and magma properties, and the geometry of the feeder dyke, we estimate the dyke overpressure. On these grounds we evaluate the volume and storage depth of the magma feeding chamber, yielding values consistent with those derived from petrologic constraints. Therefore, we could quantify the minimum volume, i.e. the excess pressure, necessary to rupture the reservoir and promote dyke initiation, which in turn, eventually leads to propagation and eruption. Hence, for the first time, we suggest a threshold for reservoir rupture at Campi Flegrei, linked to geodetically detectable magma movements that may anticipate impending eruptions.