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

A.J.L. Harris, HIGP/SOEST, University of Hawai'i, Honolulu, HI 96822

J. Dehn, Geophysical Institute/Alaska Volcano Observatory, University of Alaska, Fairbanks, AK 99775

D. Pirie, HIGP/SOEST, University of Hawai'i, Honolulu, HI 96822

Volcanic activity at both Soufriere Hills Volcano, Montserrat and Bezymianny Volcano, Kamchatka increased significantly in the latter part of 2000 triggering "thermal alarms" on automatically processed GOES and AVHRR data. Soufriere Hills has been the site of moderate to vigorous dome growth/collapse events since the initial eruption in 1995. These well-documented eruptions have produced numerous pyroclastic flows and rock falls resulting in the evacuation of nearly the entire population of the island. After a major collapse event on March 20, 2000, renewed activity formed the largest dome yet observed, producing new pyroclastic deposits in the Tar River valley. Bezymianny has been one of the most historically active volcanoes on the Kamchatkan Peninsula. A new phase of activity was first detected by way of a thermal anomaly detected in AVHRR imagery on September 21, 2000. Beginning on October 28, energy from B-type earthquakes increased, followed two days later by a gas-steam plume, which increased the alert status for the volcano. Both volcanoes continued in a heightened state of unrest for the remainder of the year.

Short wave infrared (SWIR) and thermal infrared (TIR) data from the new ASTER instrument aboard the Terra spacecraft have been used to monitor both eruptions. Nearly 40 ASTER scenes have been collected from June 1 to February 15 covering both volcanoes. Of these, a subset was chosen that had cloud free, night time images showing obvious thermal anomalies. These anomalies covered tens to hundreds of pixels and were commonly detected down to ASTER band 4 (1.66 microns) with associated recovery pixels attesting to the observed high temperatures. At Soufriere Hills, both dome and pyroclastic-related anomalies were mapped. For Bezymianny, the ASTER-observed thermal anomalies were present from June - December, 2000 (much longer than either AVHRR or Landsat ETM+ data have shown). The high spatial and spectral resolution of ASTER coupled with the excellent radiometric accuracy makes it an ideal tool for thermal anomaly detection and volcanic monitoring. Once calibrated for instrument effects and atmosphere, the brightness temperatures will be used to estimate thermal fluxes and, hence, eruption rates. In addition, the derived thermal emissivity of domes will be examined for textural variations that may be associated with changing rates of magma flux and areas of dome instability.

------------------
Submitted: American Geophysical Union Spring Meeting
Date: May 29 - June 2, 2001