M. Ramsey, Department of Geology and Planetary Science, 200 SRCC Building, University of Pittsburgh, Pittsburgh, PA 15260

Dehn, J., Geophysical Institute/Department of Geology and Geophysics, University of Alaska Fairbanks, 99775

The surfaces of both active and inactive silicic domes commonly show convoluted textural, compositional, and thermal mixing patterns. On active lava surfaces, these patterns indicate a potential change in the extrusion rate, cooling, and/or degassing of the magma. Capturing quantitative information on these parameters during an eruption can also be critical for determining the hazard state of the dome. However, eruptive activity commonly precludes any direct sampling. Field and spaceborne thermal infrared (TIR) data provide a measure of safety and are uniquely sensitive to texture, composition, and temperature. Simple retrievals of these parameters from TIR data is complicated by the mixing that occurs at all scales on the dome surface.

Because domes frequently form the late stage products of an eruption sequence, their presence can either signal the cessation of explosive activity or the beginning of a period of growth and collapse. The activity of Bezymianny and Sheveluch volcanoes has been examined in detail during the past four years with TIR remote sensing and during one field campaign. Thermal and textural anomalies seen on the surface of the lava domes change markedly during the restive state prior to larger eruptions. The movement of low-grade thermal features represent may the appearance of new fumaroles. Dome growth phases were inferred by the appearance of lower vesicularity lava (exogenous) and larger-scale heating (endogenous). Newly developed modeling techniques coupled with field and space-based TIR measurements of active domes has proven successful. It is expected these tools could add significantly to a volcano monitoring program.

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Submitted: IAVCEI General Assembly, Pucón, Chile
Date: November 14 - 19, 2004