HR: 0800h
AN: V31A-0599    [Abstracts]
TI: Viscosity Mapping of Lava Flows Using FLIR Imagery
AU: * van Manen, S M
EM: saskia.van-manen@ic.ac.uk
AF: Imperial College, Department of Earth Science and Engineering, South Kensington Campus, Imperial College, London, SW7 2AZ United Kingdom
AU: Dehn, J
EM: jdehn@gi.alaska.edu
AF: Alaska Volcano Observatory, Geophysical Institute, University of Alaska Fairbanks, 903 Koyukuk Drive, Fairbanks, AK 99775-7320 United States
AB: The relationship between viscosity and strain rate in lavas has been examined using data from literature, field observations and laboratory experiments. Handheld infrared imagery of active lavas and analogues are compared to conventional measures of rheology. Field measurements (at virtually fixed effusion rates) and laboratory experiments with honey as a lava analogue have shown that viscosity is of equal or greater importance than strain rate in the creation of surface morphology of lava flows. However, for the pāhoehoe to `a`ā textural transition, strain rate appears the dominant factor. The formation of ropes and pressure ridges occurs when the viscosity of the lava rapidly increases due to cooling of the surface. Shear at the edge of channels continually exposes fresh hot lava, keeping the viscosity of the surface low. Low shear in the center of the flow allows cooling to take place, increasing viscosity which promotes the formation of plugs and rafts. The integration of the thermal IR data and rheology modeling is a new approach that should provide further insight into the nature of lava flow emplacement, cooling and the development of characteristic morphologies.
DE: 8429 Lava rheology and morphology
DE: 8485 Remote sensing of volcanoes
SC: Volcanology, Geochemistry, Petrology [V]
MN: Fall Meeting 2005