HR: 11:20h
AN: V22A-05    [Abstracts]
TI: Analysis of Ballistics from the Vulcanian Eruptions of 1999 and 2003 of Volcán de Colima: Physical Modelling and Estimate of the Kinetic Energy.
AU: * López, M
EM: mario_lopez@ucol.mx
AF: Universidad de Colima, Carr. Colima-Coquimatlán km-9, Coquimatlán, Col 28040, Mexico
AU: Varley, N R
EM: nick@ucol.mx
AF: Universidad de Colima, Av. 25 de julio 985, Colima, Col 28045, Mexico
AB: The vulcanian-style explosions of Volcán de Colima have intensified since 1998 and are characterized by the ejection of fragments of juvenile material and dome. After the effusive phase, which begun in November of 1998, three explosions of larger magnitude occurred during 1999; then a further effusive phase started in 2001, which was followed by three explosions in July and August 2003. The object of this study is to analyze the ballistic projectiles of these explosive eruptions, to characterize them and propose physical models that can help to understand the eruptive mechanisms. The study is assisting in the improvement of the continuous monitoring strategy and risk analysis. The influence of the drag force within the atmosphere is considered since it modifies the trajectories of the projectiles. It depends on factors like: the initial velocity, shape, ruggedness and density of the fragments or blocks as well as the direction and velocity of the wind. Analysis shows initial sub-sonic velocities (<1Mach) for an ideal sphere, which implies a drag coefficient of 0.5. The maximum and minimum diameters of impact craters for the explosions of 1999 and 2003 were 10.2 and 0.15 meters, and 9.3 and 0.15 meters, respectively. For the explosions of 2003 diameters of ballistics were measured in the range 14cm to 1.43m; the maximum calculated height for the projectiles was 835m above the crater; the maximum range measured in horizontal projection was 2.2 km and the kinetic energy liberated by the total mass was 4.21x107 joules. The kinetic energy liberated during the explosions of July and August 2003, is compared to the seismic energy quantified with the broadband record.
UR: http:www.ucol.mx/volcan
DE: 0370 Volcanic effects (8409)
SC: Volcanology, Geochemistry, and Petrology [V]
MN: 2007 Joint Assembly