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What's the speed limit?: An assessment of the decompression rate of the VEI 6 eruptions at Colli Albani and mafic volcanoes worldwide

Corin Jorgenson1,2 , Katherine Dobson2, Guido Giordano3, Michael Stuckelberger4, Giovanni Fevola4, Mónica Ágreda-López5, Gero Falkenberg4,6, Tizian Kaiser4,6, Fabian Wilde7, Gregor Weber8, Luca Caricchi1

  • Affiliations: 1Department of Earth Science, University of Geneva, Geneva, Switzerland; 2 Department of Civil and Environmental Engineering, University of Strathclyde, Glasgow, UK; 3Department of Science Geology, University of Roma Tre, Rome, Italy; 4Centre for X-ray and Nano Science, Deutsches Elektronen-Synchrotron DESY, Hamburg, Germany; 5 Department of Physics and Geology, University of Perugia, Perugia, Italy; 6 Department of Physics, University of Hamburg, Hamburg, Germany; 7 Helmholtz-Zentrum Hereon, Geesthacht, Germany; 8School of Earth Sciences, University of Bristol, Bristol, UK

  • Presentation type: Poster

  • Presentation time: Tuesday 16:30 - 18:30, Room Poster Hall

  • Poster Board Number: 100

  • Programme No: 3.16.27

  • Theme 3 > Session 16

Abstract

The key driver of explosive mafic volcanism remains an enigma in volcanology. One key aspect often pointed to is the role of rapid magma ascent, as rapidly ascending magma allows for the volatiles to remain coupled with the melt. Such is the case for Colli Albani (Italy), a mafic-alkaline caldera complex with seven VEI 6-7 eruptions during its eruptive history. Clinopyroxene chemistry, melt inclusion vapor bubble volume fraction, and volatile contents of melt inclusions point to an initially volatile rich bubble-bearing magma, which was rapidly transported to the surface, resulting in an extremely explosive eruption (Jorgenson et al., 2024). However, a robust quantification of decompression rates is still missing for Colli Albani. Furthermore, the overall relationship between eruption intensity, magma composition, and decompression rate for mafic explosive eruptions is poorly understood in the literature. We collected high-resolution X-ray tomography to characterize vesicle textures, including bubble number density, which can be used as a proxy for decompression rate (Toramaru 2006). We will present a collection of decompression rates from mafic tephra to clarify the role of magma ascent in modulating the intensity of mafic explosive eruptions and develop a framework for the explosivity of the Colli Albani volcano.