HR: 11:40h
AN: V42B-06    [Abstracts]
TI: Release of Kinetic Energy During Explosive Events at Popocatepetl Volcano (Mexico): Constraints From Fragmentation Experiments
AU: * Alatorre-Ibarguengoitia, M A
EM: alatorre.miguel@gmail.com
AF: Instituto de Geofisica, Universidad Nacional Autonoma de México, Circuito Exterior, Ciudad Universitaria, Coyoacan, Mexico, DF 04510, Mexico
AU: Delgado-Granados, H
EM: hugo@tonatiuh.igeofcu.unam.mx
AF: Instituto de Geofisica, Universidad Nacional Autonoma de México, Circuito Exterior, Ciudad Universitaria, Coyoacan, Mexico, DF 04510, Mexico
AU: Ulrich, K
EM: lesulis@gmx.net
AF: Centro de Vulcanologia e Avaliação de Riscos Geologicos, University of the Azores, 9501 - 801 Ponta Delgada, Portugal
AU: Ulrich, K
EM: lesulis@gmx.net
AF: Department of Earth and Environmental Sciences, Ludwig-Maximilians-University Munich, Theresienstrasse 41, Munich, 80333, Germany
AU: Dingwell, D B
EM: dingwell@lmu.de
AF: Department of Earth and Environmental Sciences, Ludwig-Maximilians-University Munich, Theresienstrasse 41, Munich, 80333, Germany
AB: The potential energy of gas overpressure in bubbles may cause magma fragmentation, creating new surface. The surplus of energy is transformed into kinetic energy for ejection of particles. The efficiency of the fragmentation process to transform the potential energy into kinetic energy during explosive eruptions is a key parameter for hazards assessment. In order to investigate the fragmentation behavior, we performed rapid decompression experiments at high temperature (850°C) using natural samples from Popocatepetl volcano, Mexico. The minimum pressure differential that leads to complete sample fragmentation (fragmentation threshold) is inversely proportional to the porosity, in accordance with previous studies (Spieler et al., 2004). Further, we used several approaches to characterize the fragmentation efficiency as a function of open porosity/ applied pressure: Grain-size distribution, surface increase, and fractal analysis. SEM images of the resulting pyroclasts show that brittle deformation dominates due to the high decompression rates. These images also show that the experimental pyroclasts have similar morphology to natural ashes from Popocatepetl volcano. On the other hand, we calculated the launching velocities of the ballistic projectiles ejected during explosive events at Popocatepetl volcano using a ballistic model considering the drag coefficient for volcanic particles. Combining both approaches (potential energy from scaled experiments and kinetic energy from the distribution of the ballistic projectiles) we constrain the exsolved volatile content and provide information on the release of kinetic energy during explosive events at Popocetapetl volcano. In this way, hazard assessment could be refined.
DE: 8414 Eruption mechanisms and flow emplacement
DE: 8428 Explosive volcanism
DE: 8434 Magma migration and fragmentation
DE: 8445 Experimental volcanism
DE: 8488 Volcanic hazards and risks
SC: Volcanology, Geochemistry, and Petrology [V]
MN: 2007 Joint Assembly