Volcanic plume height correlated with magma-pressure change at Grímsvötn Volcano, Iceland

• Main Authors: Hreinsdóttir, Sigrún, Sigmundsson, Freysteinn, Roberts, Matthew, Björnsson, Halldór, Grapenthin, Ronni, Arason, Pórdur, Árnadóttir, Thóra, Hólmjárn, Jósef, Geirsson, Halldór, Bennett, Richard, Gudmundsson, Magnús, Oddsson, Björn, Ófeigsson, Benedikt, Villemin, Thierry, Jónsson, Thorsteinn, Sturkell, Erik, Höskuldsson, Ármann, Larsen, Gudrún, Thordarson, Thor, Óladóttir, Bergrún Arna
• Other Authors: University of Iceland Reykjavik, Nordic Volcanological Center, Institute of Earth Sciences, Institute of Earth Sciences University of Iceland, University of Iceland Reykjavik -University of Iceland Reykjavik, Department of Agricultural & Food Economics, University of Reading (UOR), Environnements, Dynamiques et Territoires de la Montagne (EDYTEM), Université Savoie Mont Blanc (USMB Université de Savoie Université de Chambéry )-Centre National de la Recherche Scientifique (CNRS), Department of Earth Sciences Gothenburg, University of Gothenburg (GU)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2014
• Subjects: [SDE.MCG]Environmental Sciences/Global Changes; [SDE.BE]Environmental Sciences/Biodiversity and Ecology; [SDE.IE]Environmental Sciences/Environmental Engineering; [SDE.ES]Environmental Sciences/Environmental and Society; [SHS.GEO]Humanities and Social Sciences/Geography; Grimsvotn; Iceland
• Online Access: https://hal.archives-ouvertes.fr/hal-02011631

International audience Magma flow during volcanic eruptions causes surface deformation that can be used to constrain the location, geometry and internal pressure evolution of the underlying magmatic source(1). The height of the volcanic plumes during explosive eruptions also varies with magma flow rate, in a nonlinear way(2,3). In May 2011, an explosive eruption at Grimsvotn Volcano, Iceland, erupted about 0.27 km(3) dense-rock equivalent of basaltic magma in an eruption plume that was about 20 km high. Here we use Global Positioning System (GPS) and tilt data, measured before and during the eruption at Grimsvotn Volcano, to show that the rate of pressure change in an underlying magma chamber correlates with the height of the volcanic plume over the course of the eruption. We interpret ground deformation of the volcano, measured by geodesy, to result from a pressure drop within a magma chamber at about 1.7 km depth. We estimate the rate of magma discharge and the associated evolution of the plume height by differentiating the co-eruptive pressure drop with time. The time from the initiation of the pressure drop to the onset of the eruption was about 60 min, with about 25% of the total pressure change preceding the eruption. Near-real-time geodetic observations can thus be useful for both timely eruption warnings and for constraining the evolution of volcanic plumes.