MAPPING HYDROTHERMAL MINERALS AT THREE SISTERS VOLCANOES, OREGON USING HYPERSPECTRAL IMAGERY
We used 1996 Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) hyperspectral data to map hydrothermal minerals at Three Sisters. Prior to analysis of the data, we applied atmospheric radiation transfer models to remove water vapor and carbon dioxide data from the spectra because of the 20 km altitude at which the AVIRIS sensors were flown. Field spectra were used reduce the data to surface reflectance. Following image classification, resultant maps were warped to a 30 m U.S. Geological Survey DEM (digital elevation model) to produce a three dimensional image showing the distribution of hydrothermal minerals relative to slope. Field samples were collected and spectrally analyzed in the laboratory to check mapping results.