Objectif Some andesitic volcanoes at subduction plate margins experience periods of sub-continuous eruption during years, decades, or centuries (open-vent activity periods). Such long-lived periods typically include outgassing events, extrusion of viscous lava flows and domes, and explosive activity of low to moderate intensity. This background activity can be disrupted by violent explosive events of short duration (violent strombolian to subplinian in style), with potential generation of pyroclastic flows. In populated areas these explosions may be highly hazardous because they take place with little or no warning during ongoing open-vent activity. The conditions of magma transfer and controls on fragmentation associated with both the background explosive phases and the paroxysmal events are poorly constrained. To address these questions we propose to combine (1) morphological studies of particles from tephra fall deposits of background and paroxysmal explosive eruptions of Tungurahua volcano (Ecuador) which have known an open-vent activity period since 1999 with (2) analogue decompression experiments of 3-phase flows. Quantitative analyses of the shape and surface structure of pyroclastic material will be performed using innovative tools for morphological analyses (Malvern Morphologi G3 instrument for the study of the shape, and MeX metrology software for the 3D analysis of the surface roughness). The decompression experiments will be set up using a viscous solution of acetone, gum-rosin and particles to simulate the ascent of an expanding 3-phase flow. The morphology data and the analogue experiments will allow us to decipher the fragmentation mechanisms and to investigate the physical conditions of magma ascent in the conduit to the surface. This work will inform not only hazard assessment for andesitic volcanoes but will also help to constrain source terms for models of ash dispersion from volcanic plumes. Champ scientifique natural sciencescomputer and information sciencessoftwarenatural sciencesearth and related environmental sciencesgeologyvolcanologysocial sciencessociologygovernancecrisis management Programme(s) FP7-PEOPLE - Specific programme "People" implementing the Seventh Framework Programme of the European Community for research, technological development and demonstration activities (2007 to 2013) Thème(s) FP7-PEOPLE-2012-IEF - Marie-Curie Action: "Intra-European fellowships for career development" Appel à propositions FP7-PEOPLE-2012-IEF Voir d’autres projets de cet appel Régime de financement MC-IEF - Intra-European Fellowships (IEF) Coordinateur UNIVERSITY OF BRISTOL Contribution de l’UE € 231 283,20 Adresse BEACON HOUSE QUEENS ROAD BS8 1QU Bristol Royaume-Uni Voir sur la carte Région South West (England) Gloucestershire, Wiltshire and Bristol/Bath area Bristol, City of Type d’activité Higher or Secondary Education Establishments Contact administratif Audrey Michael (Mrs.) Liens Contacter l’organisation Opens in new window Site web Opens in new window Coût total Aucune donnée