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Volcano-tectonic controls on the 3D architecture of sub-volcanic magma storage at Campi Flegrei, Italy

Michael Stock 1, Fay Amstutz1, Yasemin Guven1, Clara Hogan1, Victoria Smith2, Roberto Isaia3, Charline Lormand4, Luca Caricchi4, Guido Giordano5

  • Affiliations: 1School of Natural Sciences, Trinity College Dublin, Dublin, Ireland; 2School of Archaeology, University of Oxford, Oxford, UK; 3Vesuvius Observatory, INGV, Naples, Italy; 4Department of Science, Roma Tre University, Rome, Italy; 5Department of Earth Sciences, University of Geneva, Geneva, Switzerland

  • Presentation type: Talk [Invited]

  • Presentation time: Friday 09:45 - 10:00, Room R290

  • Programme No: 3.10.6

  • Theme 3 > Session 10

Abstract

Understanding pre-eruptive magma storage depth(s) is essential for the reliable interpretation of monitoring data at active volcanoes. While geophysical datasets provide important information about the current state of a volcanic system, petrological studies of historic eruptions are essential for determining variability in pre-eruptive conditions beneath long-lived centres. However, as petrological methods rely on pressure-dependent phase equilibria, they provide an inherently one-dimensional insight into magma accumulation depths with no lateral information. Such lateral information may be particularly important in large caldera systems such as Campi Flegrei (Naples, Italy) where recent (<15 kyr) eruptions have been dispersed across a large area, with vents located in diverse volcano-tectonic settings. Here, we present an overview of historic petrological and geophysical constraints on magma storage conditions at Campi Flegrei which reveal a complex multi-level magmatic system. We then use a novel machine learning-based clinopyroxene thermobarometric model to systematically supplement these with new high precision crystallisation depth estimates for post-15 kyr magmas erupted at vents across the caldera. By comparing the crystallisation depths of magmas erupted in different spatial locations, we identify lateral variations in magma storage conditions, gaining a three-dimensional picture of the sub-volcanic architecture which agrees with independent geophysical constraints. Importantly, our results show a difference in magma storage depths which correlates with volcano-tectonic setting, indicating a regional structural control on magma storage and evolution. Our results are important for volcano monitoring, suggesting that pre-eruptive activity in different parts of large volcanic systems might be characterised by distinct signs of unrest.