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Huge landslide threatens at Alaskan volcano.

Jutting steeply out of the waters of Cook Inlet, Alaska's Mount St. Augustine presents a stony profile that seems to transcend time. But a study of this active volcano indicates that every 150 to 200 years, large parts of the mountain have collapsed and fallen into the sea. If the past cycle continues, a major avalanche could come during the next several decades, volcanologists warn.

In light of these new findings, geological researchers question the wisdom of the President's proposed 1993 budget, which seeks far-reaching cuts in programs that monitor earthquake and volcanic hazards in the United States.

Most volcanologists have thought that major landslides occur only rarely on volcanoes, perhaps once or twice in the lifetime of the mountain. But the new study shows at least one volcano has a habit of collapsing. James E. Beget and Juergen Kienle of the Alaska Volcano Observatory and the University of Alaska in Fairbanks report in the April 23 Nature that large landslides have shorn Mount St. Augustine a minimum of 11 times in the past 1,800 to 2,000 years.

"This is the first time this type of behavior has been documented for a volcano," says Beget. He says volcanologists have not studied most of the other volcanoes in the world well enough to know if they behave the same.

Using the carbon-14 dating technique, the Alaskan researchers determined the ages of individual debris layers piled one atop the other. The most recent slide occurred during an eruption in 1883. At that time, the north side of the 1,200-meter-tall volcano slide into the sea, leaving a large horseshoe-shaped crater.

Such an avalanche might have carried away about 10 percent of the volcano, estimates Lee Siebert of the Smithsonian Institution in Washington, D.C.

Since 1883, a series of eruptions has filled in the hole left by the last landslide. With each successive eruption, the top of the volcano grows steeper and more unstable, says Beget, who believes St. Augustine has reached a point where another collapse is possible. Judging from past deposits, the next landslide would barrel down the north side of the volcano. As it crashed into the sea, the debris would generate a tsunami wave heading in the direction of cities and oil platforms in Cook Inlet.

St. Augustine is only one of many active volcanoes in the western states. Despite the potential threat, the proposed 1993 budget for the U.S. Geological Survey would reduce its volcanic hazard program by nearly a quarter and slash 83 percent from current federal funding for the Alaska Volcano Observatory. The earthquake hazard program would also suffer a large cut.
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Title Annotation:Mount St. Augustine
Author:Monastersky, Richard
Publication:Science News
Date:Apr 25, 1992
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