M S Ramsey and J H Fink (Dept. of Geology, Arizona State Univ., Box 871404, Tempe, AZ 85287-1404; ph. 602-965-1790; email: ramsey@elwood.la.asu.edu)

Monitoring lava dome emplacement and growth following eruptions provides insights into further lava extrusion and future eruptive episodes. The dome's surface texture, structure and possibly composition may change dramatically following its initial formation. On site studies of these domes are complicated by heat and gas emission as well as the threat of future eruptions. The use of remote sensing helps to mitigate these hazards and, in addition, provides valuable information on the temporal changes in temperature and surface morphology.

The current study utilizes airborne data that span the EM spectrum from 0.45 to 12.0 microns at high spatial resolution. The future ASTER instrument scheduled for launch in 1998 aboard the EOS-A satellite will gather similar multispectral data over the entire globe. Remote sensing data were acquired over recent (600 - 2500 years BP) silicic domes throughout the southern High Cascade Range. These data not only provide important information on the structure of the domes, but also act as test locales for understanding the effects of vesicularity and vitrification without the complications of degassing, high temperatures and further eruptions. It has been shown that the pumiceous surface of rhyolitic domes varies greatly as a function of dome size, emplacemenet time and volatile content. Mapping of these surface features provides insights into the internal structure and flow dynamics of the dome. Chemical variations due to dike stratification and/or selective tapping and withdrawl can be analyzed to further constrain magma mixing, viscosity contrasts and eruptive dynamics. The effect of glass coupled with vesicularity combine to complicate remote sensing data. These effects must be understood prior to monitoring active dome formation.

Finally, the addition of "artifical" temperature anomalies and the degradation of the spatial resolution of the current data have been performed in order to simulate ASTER data.

This work supported under P R Christensen by NASA grant NAS5-31371.

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Presented at: American Geophysical Union Fall Meeting
Date: 1994