HR: 15:30h
AN: V33C-07    [Abstracts]
TI: Flow Simulations Reproducing the 1982 Eruption of the el Chichón Volcano, Mexico.
AU: * Capra, L
EM: lcapra@geociencias.unam.mx
AF: Centro de Geociencias, UNAM, Campus Juriquilla, Queretaro, Qro 76230, Mexico
AU: Arce, J
EM: jlarce@geologia.unam.mx
AF: Instituto de Geologia, UNAM, CU, Coyoacan, Mexico DF, DF 04510, Mexico
AU: Macías, J
EM: macias@geofisica.unam.mx
AF: Instituto de Geofisica, UNAM, Cu, Coyoacan, Mexico DF, DF 04510, Mexico
AB: During the March 28, 1982 eruption of El Chichón volcano (México) different types of flows affected several villages, killing more than 2000 people. This disaster showed the need to elaborate a hazard map for this volcano. The observation of the 1982 eruption coupled with the reconstruction of past events, revealed that main hazards at El Chichón consist of block-and-ash flows, surges and lahars. In order to construct a hazard map of the volcano, computer simulations were performed using the pre-1982 topography (10 m in pixel resolution) to mimic past flows and calibrate the different physical coefficients needed as input parameters in the computer routines. Block and ash flow simulations fitted quite well with observed trajectories (FLOW3D with a0: 0.1-0.2) and inundation limits (with TITAN2D, friction angle: 30º, pile volume: 0.01*106-0.1*106 m3). The main uncertainties were in the more distal portions where it was very difficult to obtain reliable results for flow inundation limits and thicknesses. The ENERGY CONE was applied with a H/L of 0.1 giving a distribution for surges consistent with the S1 deposit, the largest surge emplaced during the 1982 eruption. Finally, lahars were reproduced with LAHARZ using volumes of 4, 2 and 1*106 m3, obtaining surprising results on ravines that were not affected during 1982, but that could be threatened in the future. This work evidences that despite some limitations, mainly related to the topography resolution, computer simulations are useful tools during the preparation of volcanic hazards maps. They must be coupled with detailed data obtained by field work, which is crucial to check the reliability of computer simulations.
DE: 8428 Explosive volcanism
DE: 8488 Volcanic hazards and risks
SC: Volcanology, Geochemistry, and Petrology [V]
MN: 2007 Joint Assembly