After a long-simmering summer where Redoubt Volcano had been at alert level warning and aviation code yellow, the Alaska Volcano Observatory on Tuesday morning lowered the level to normal and the aviation code to green.

"The volcano appears to have returned to its normal background condition and for now poses no immediate threat of eruptive activity," AVO scientists said in a volcanic activity notice issued about 10:45 a.m. Sept. 29.

The volcano 75 miles northwest of Homer first erupted with a gas and steam explosion on March 15. Between March 22 and April 4 it blew again, with ash and gas rising as high as 65,000 feet.

The April 4 explosion dropped ash about 1/8-inch thick on much of Homer. Mud and ash, or lahars, flowing down Redoubt Valley forced the Drift River oil terminal to be shut down.

Since the April 4 explosion, a lava dome near Redoubt's summit had been growing, ultimately reaching 91 million cubic yards in volume. In earlier alerts, AVO had warned that there was a risk of the lava dome collapsing and causing ash clouds and downstream flooding from lahars. Evidence of dome instability has declined and the dome has not grown since late July. Scientists said they now believe the possibility of dome collapse is small.

The area around the dome remains hazardous, AVO cautioned, with a risk of rock falls and steaming near the dome. High levels of sulfur dioxide, carbon dioxide and hydrogen sulfide could occur, with sulfur being smelled nearby and steam plumes seen.

Scientists will continue to monitor Redoubt and other Cook Inlet volcanoes. If Redoubt becomes active again, instruments on Redoubt would show an increase in background level hours or even days before a potential eruption.

For more information, visit AVO's Web site at www.avo.alaska.edu.

Michael Armstrong can be reached at michael.armstrong.@homernews.com.