At the meeting, Ramsey reported on the success of ASTER in studying recent activity at the Soufrière Hills Volcano, with colleagues at the University of Hawaii, and the Bezymianny Volcano in Russia, with researchers from the Geophysical Institute/Alaska Volcano Observatory, University of Alaska.

Remote monitoring of volcanoes is important, said Ramsey, estimating that 500 million people worldwide live near volcanoes. Advance notice of eruptions can avert calamity, and ASTER, Ramsey believes, is an important new tool.

A picture of Bezymianny Volcano on the Kamchatka Peninsula, Russia, taken by ASTER on May 1, 2000. Overlain is Short Wave Infrared data, acquired on Oct. 25, 2000. The image is colored red to highlight the active thermal anomaly.

Built in Japan for the Ministry of Economy Trade and Industry, ASTER is aboard the NASA satellite Terra, which was launched in December 1999, as part of NASA’s Earth Observing System, a project whose goal is to obtain a better understanding of the interactions between the Earth’s biosphere, hydrosphere, lithosphere, and atmosphere.

ASTER combines three imaging technologies: visible/near infrared (VNIR); short-wave infrared (SWIR); and thermal infrared (TIR). These three systems each take “snapshots” of the Earth’s more than 1,000 volcanoes about every two weeks, though Ramsey said the time can be adjusted to about every five days.

The IVIS lab combines the data from all three systems to provide researchers with a thermal “picture” of the areas being studied.

“Each of these wavelength regions tells us something very different about the state of the volcano,” Ramsey explained. “In the TIR, we can look at cooler temperatures — under 300 degrees Celsius — the mineralogy of the volcano, and the textures of the lavas. In the SWIR, much hotter temps — from 500 to1200 degrees Celsius—can be measured as well as giving us fundamental information about minerals such as sulfur, clays, and other high-temperature minerals.

“These are important because they occur in areas where there is a lot of hydrothermal activity. Finally, in the VNIR, we can look at the volcano very much like you would with a photograph, except here we have more information on iron-bearing minerals and the surrounding vegetation.”

Ramsey and his colleagues reported that they were able to observe changes to the two volcanoes, which increased their activity substantially during the last part of 2000. Ramsey praised the high spatial and spectral resolution of ASTER as ideal for detecting changes in the Earth’s temperature and as a means of monitoring volcanoes worldwide.

“The brightness temperatures will be used to estimate thermal fluxes and, hence, eruption rates,” Ramsey said. “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.”

Currently, Ramsey and other volcanologists involved in remote sensing use satellites and programs run by the National Oceanic and Atmospheric Administration (NOAA), such as the Advanced Very High Resolution Radiometer AVHRR or the Geostationary Operational Environmental Satellite (GOES), which are designed primarily for weather forecasting.

Despite some of ASTER’s new capabilities, Ramsey said they won’t abandon using the NOAA images.“Because ASTER doesn’t have the fast repeat times that AVHRR or GOES does, we aren’t in a position to watch eruptions begin and progress,” said Ramsey. “But with the other abilities of ASTER, we can observe changes on the week time scale. This is very important after the initial eruption and the formation of a lava dome. These act like corks in many ways and subtle changes in their temperature, composition, or texture reveal information about potential upcoming eruptions.”

For more information, to view ASTER images, or to read more about Ramsey’s work, log on to http://ivis.eps.pitt.edu/projects/nopac/.

—John Fedele