BY MICHAEL ARMSTRONG

STAFF WRITER

The Alaska Volcano Observatory on Monday afternoon downgraded the caution level to watch and the aviation code to orange for Mount Redoubt. According to an activity notice, current seismicity suggested a sudden explosive eruption wasn't imminent. After Saturday's explosion that dumped ash on Homer, Redoubt is now emitting a minor amount of ash. Satellite and radar images showed a small steam and ash plume at an altitude of about 20,000 feet, AVO scientists said in an update on Tuesday afternoon.

After Saturday's explosion, Redoubt continues to extrude lava and build up the summit dome, as measured in "drumbeat" seismicity on webicorders on the volcano.

"You might think of the volcano as a little steam engine," U.S. Geological Survey geologist Margaret Mangan explained in a press conference Monday afternoon. "It's pushing out lava as well as gas. Each one of those resonances is the puff of the steam engine."

Mangan said an overflight of Redoubt showed ice still in the summit crater, with the potential for more melting and lahars, or muddy flows of ice and debris. The overflight also measure levels of sulfur dioxide and carbon dioxide twice as high after the April 4 explosion as from before.

Redoubt remains in a highly unpredictable phase of its eruption. As the lava dome builds up, it could collapse, causing further explosions. Scientists do not know yet if the dome collapsed in the April 4 explosion. If Redoubt enters a more steady-state phase, as it did later in the 1989-90 eruption, scientists can forecast its behavior more accurately.

As scientists wrote in previous notices downgrading the alert status, "Additional significant explosive events with accompanying ash clouds, ash fall and mudflows are possible and can occur with little or no warning."

For updates, visit the AVO Web site at www.avo.alaska.edu or call (907) 786-7478.

Michael Armstrong can be reached at michaelarmstrong.@homernews.com.