HR: 1400h
AN: V33A-06    [Abstracts]
TI: The November 2002 Pyroclastic Flows at El Reventador, Ecuador: Computer Simulations Using the TITAN Thin-layer Code
AU: Burkett, B
EM: Brett Burkett [tarlin@gmail.com]
AF: Department of Geology, 876 Natural Science Complex University at Buffalo, Buffalo, NY 14260, United States
AU: * Sheridan, M F
EM: mfs@geology.buffalo.edu
AF: Department of Geology, 876 Natural Science Complex University at Buffalo, Buffalo, NY 14260, United States
AU: * Sheridan, M F
EM: mfs@geology.buffalo.edu
AF: Center for Geohazards Studies, 876 Natural Science Complex University at Buffalo, Buffalo, NY 14260, United States
AB: On November 3, 2002, El Reventador volcano, located on the eastern flank of the Ecuadorian Andes, produced a sudden, violent eruption culminating in a 17km high column containing mostly steam and ash. Explosions in the initial phase created a summit crater while generating four lithic-rich andesitic pyroclastic flows. The longest of these flows traveled ESE out of the breached caldera, obliquely overriding the 200-400m southern caldera wall, reaching the Quijos River 8km distant. This flow crossed the major oil pipelines of Ecuador, displacing a pressurized crude oil pipeline more than 100m. The flows contained mostly lithic fragments with only minor juvenile pumice. The accompanying ash-cloud surge deposited a thin layer on top of the PF deposit, indicating an abundance of gas within the flow. The eruption came with practically no warning and yet had a large socio- economic impact for Ecuador. While the flows themselves resulted in no loss of life, the lack of significant precursor activity underscores the necessity for detailed pre-eruption knowledge of the potential hazards and risk zones around a particular volcano so as to be prepared in the event of such "surprise" eruptions. In conjunction with field mapping, computer models of volcanogenic flows can be used not only to identify risk zones but to understand the evolution of these flows. A new set of computer simulations using the TITAN (www.gmfg.buffalo.edu) thin-layer code allows a more complete exploration of important flow properties associated with this type of eruption. Realizations of this code simulate the path, extent, flow thickness, velocity, and momentum of the flows given the set of initial conditions (volume, starting location, flux hydrograph, internal friction, and basal friction). The TITAN code was used to simulate the four lithic-rich pyroclastic flows generated at the beginning of the 2002 eruption. Using field estimated volumes and starting positions of the PFs, simulations of the two largest flows, confined in major channels along the northern and southern walls of the old caldera, provided qualitatively good fits to mapped deposits. Specifically, these models produced features comparable to the real flows including overtopping of the southern caldera wall, diversion by topographic obstacles, and channeling. The two smaller flows, while producing narrow, linear deposits, spread much farther laterally in the simulations. This phenomenon may reflect some unmodeled flow dynamic such as yield strength, which might only become substantial with small volumes. Possibly, as the DEM was constructed from a topographic map, the digitization or smoothing may have erased small channels which governed the real flows but could not be represented in simulation.
UR: http:www.gmfg.buffalo.edu
DE: 8414 Eruption mechanisms and flow emplacement
DE: 8428 Explosive volcanism
DE: 8488 Volcanic hazards and risks
DE: 9360 South America
SC: Volcanology, Geochemistry, and Petrology [V]
MN: 2007 Joint Assembly