Watching for a big blowup: Satellite proves worth with detailed views of active volcanoes

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When monitoring some of the most explosive volcanoes in the world, one of the best places to be is 440 miles away.

NASA
Red glows indicate the presence of heat from the Klyuchevskaya volcano top and the Bezymianny volcano (bottom). Though the eruption has subsided, a small plume of ash is still visible in this false-color image. Reds indicate heat, cooler areas are green, the coolest areas are blue. The Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on the Terra satellite captured this image Wednesday.
Click photo for larger image.

And not just because that's a safe distance.

It happens to be the orbital altitude of Terra, a giant satellite launched in late 1999 as part of NASA's Earth Observing System. Among its array of instruments for studying Earth is an infrared camera that is giving scientists some unprecedented views inside some very dangerous volcanoes.

This type of instrument could significantly improve forecasts of eruptions, said Michael Ramsey, a University of Pittsburgh volcanologist who has been using the camera, called the Advanced Spaceborne Thermal Emission and Reflection Radiometer, or ASTER, to study volcanoes in the North Pacific.

Better forecasts would be particularly important for the volcanoes in the Aleutian Arc and Russia's Kamchatka Peninsula. These are some of the most volatile and remote volcanoes in the world, but also lie underneath one of the world's busiest air trade routes.

ASTER has shown promise that it could provide earlier warnings of eruptions, based on observations during its first two years of operation, Ramsey reported at last month's meeting of the American Geophysical Union. Details of ASTER research by Ramsey, director of Pitt's Image Visualization and Infrared Spectroscopy Laboratory, and Jonathen Dehn, a volcanologist at the Alaska Volcano Observatory, also will be published in an upcoming special issue of the Journal of Volcanology and Geothermal Research.

The findings were so encouraging that Ramsey was recently named a full member of the ASTER scientific team and was awarded $600,000 by NASA to create a system linking ASTER with existing weather satellites used to monitor volcanoes of the Aleutian Arc.

NASA
A more conventional view of the Bezymianny Volcano on Russia's Kamchatka Peninsula, which started to erupt violently on January 13. The ash plume, which reached a height of 3.75 miles, shows up clearly in this Moderate Resolution Imaging Spectroradiometer (MODIS) image acquired on the following day by NASA's Aqua satellite. Images of the volcano are posted regularly on a NASA Natural Hazards web page.
Click photo for larger image.

But within a few years, the ASTER mission is set to end and NASA has no concrete plans for a replacement. And no one can be sure how President Bush's call to redirect the space agency to exploration of the moon and Mars will affect future missions.

"There is a lot of uncertainty," acknowledged John LaBrecque, manager of NASA's solid earth and natural hazards program. Savings from ending the shuttle and space station programs are to be diverted to the expanded exploration effort, but it's still too early to know the impact on earth science missions, he said.

Earth remains the best prototype for perfecting methods of planetary exploration, however, LaBrecque said. So NASA likely will continue to sponsor Earth-directed sensors such as ASTER, in part as a means of developing sensors that will be useful in exploring other planets.

"Astronauts' eyes are extremely important, but they can only view a limited portion of the light spectrum," he noted. Infrared cameras, synthetic aperture radars and other space-based instruments provide important, complementary data during planetary exploration.

Getting scientists to agree on which type of instruments to fly, however, can be troublesome, Ramsey said. "It's always this competition among scientists who each have their pet wavelength," he explained. Most earth scientists are much more familiar with -- and supportive of -- instruments that operate at visual wavelengths than they are of heat-sensing infrared cameras.

That is changing, LaBrecque said, and there is interest in flying additional thermal imaging sensors.

U.S. Geological Survey
A view of the Bezymianny volcano from ground level. Scientists will visit the volcano this summer to confirm the accuracy of data on the volcano gained through satellite imagery.
Click photo for larger image.

ASTER, a joint project of NASA and Japan's Ministry of Economy, "is a very successful instrument," he said. In addition to volcanology, it is used to study glaciers, geology, tectonics and urban change.

Ramsey said ASTER is unique among orbiting infrared cameras in terms of its high resolution. Whereas the infrared cameras on weather satellites can view areas only as small as a square kilometer, ASTER can focus on areas as small as 90 square meters. The camera also is capable of stereoscopic imaging, providing topographic information.

For volcano applications, that means scientists can use ASTER to see features within a volcano, such as the growth of lava domes or identifying fractures. The heat sensed by the camera reflects both the temperature of the rock and the rock's "emissivity" -- a combination of texture and composition that determines how well it emits heat.

Ramsey has developed an additional technique that determines the amount of bubbles in the rock. An increasing percentage of bubbles, he noted, is a signal that pressure is building and an eruption may be imminent.

Dehn said the Alaska Volcano Observatory routinely uses weather satellites to keep an eye on about 160 volcanoes, extending from the Oregon north and west along the Aleutian Arc to Russia's Kamchatka Peninsula. Only about 20 of those volcanoes have seismic monitors. Most of the volcanoes are never visited, which makes space observation the only way to keep track of them.

"The only view we have of them is by satellite," he added. "It allows us to cover a lot of ground inexpensively."

Providing an early warning of eruptions is most important for those volcanoes near populated areas. But the ash clouds of even the remote volcanoes are hazards for aircraft. Weather satellites allow volcanologists to warn of eruptions a few hours in advance. In some cases, the warnings can be made a day or two in advance.

But Dehn said ASTER is able to detect signs of eruptions a month or more in advance. Unlike weather satellites, which pass over the Aleutian Arc every few hours, ASTER can provide views of each volcano only every few weeks. Still, it might be reasonable to use such an instrument to extend aircraft warnings up to a week in advance.

The Alaska Volcano Observatory typically sees three or four eruptions each year, though the last year or so has been unusually quiet. The last Aleutian volcano to erupt was Mount Cleveland in 2001.

Last summer, Ramsey and his Alaskan colleagues visited an inactive volcano, Black Peak, to gather rock samples that confirmed measurements they had made with ASTER.

On the Kamchatka Peninsula, however, four volcanoes are erupting now and Ramsey and his colleagues will visit one of those, Bezymianny, this summer to obtain further confirmation that the ASTER readings match those collected on the ground.


Post-Gazette science editor Byron Spice can be reached at bspice@post-gazette.com or 412-263-1578.


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