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

Intermediate to silicic lava domes commonly found capping active volcanic conduits can preserve an enormous quantity of information on the system's activity state. Such data could include the pressure, temperature, flow rate, and degassing state of the lava as it is extruded. Further, similar lavas found on inactive systems can serve as analogs for active domes thereby mitigating potentially hazardous field work while validating models. The clear objective is to collect data and refine models/techniques at the inactive sites so as to better understand the data from active systems, which reveal the potential hazard state of the volcano. However, in order to study both systems under similar conditions, a set of data collection techniques must be equally applicable to both. One obvious choice is remote sensing, which mitigates hazards to scientists in the field, can be collected relatively cheaply under most conditions, and can be an effective monitoring tool. In the past several years, new airborne and space-based instruments have provided data in multiple wavelength regions never before collected over volcanic flows and domes. One of the most promising satellite instruments for volcanology is the ASTER instrument launched by NASA in late 1999. Because it is the first spaceborne sensor to acquire high spatial resolution data from the visible to thermal infrared (TIR) wavelength region and has the ability to generate digital elevation models, it is particularly useful for numerous aspects of volcanic remote sensing. For example, its multispectral TIR capability is critical for monitoring low temperature anomalies and mapping both chemical and textural variations on the dome surfaces. However, the ability to derive this level of quantitative information currently relies on accurate field based data collection, laboratory modeling, and the development of new computer-based tools.

Over the past three years, ASTER data acquired over the active dome-forming eruptions of Bezymianny and Sheveluch Volcanoes (Kamchatka, Russia) and Soufrière Hills Volcano (Montserrat) have been analyzed. Data have also been collected for inactive silicic lava domes at Unzen Volcano (Japan), Black Peak Caldera (Alaska), and Medicine Lake Caldera (California). Data from the active sites were used to both monitor eruptions and map the volcanic products. It was found that thermal anomalies varied significantly on the active domes and clearly show the onset of new phases of activity as well as the semi-quiescent hydrothermal background. However, these anomalies complicate the extraction of surface emissivity, which reveals information about the petrology and texture of the lava. The accurate separation of remotely-acquired field and spaceborne TIR radiance data into temperature and emissivity is critical for quantitative volcanological modeling. The focus of this work is to further refine the extraction of accurate temperature and emissivity from TIR data. Field-based validation as well as spectral analysis of the reconstructed emissivity has been performed to better quantify the chemistry and texture of the lava surfaces.

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Submitted: American Geophysical Union Spring Meeting
Date: May 17 - 21, 2004