Redoubt volcano simmered down Monday after a rumbling weekend, but scientists are still anticipating a possible eruption, according to the Alaska Volcano Observatory.

A marked increase in seismic activity led scientists to upgrade the aviation color code for Redoubt from yellow to orange Sunday, indicating an eruption may be imminent. Seismic activity lessened a bit early Monday but was still above "background" or normal levels, and the AVO kept the aviation code at orange.

Geologists flew over the volcano Monday and found it huffing out a diffuse plume made up of sulfur gasses and water vapor.

There are several holes in the ice that covers the 10,197-foot peak where the warm gases have escaped. Scientists checked to see if the holes had widened overnight. They hadn't, said Chris Waythomas USGS geologist at AVO.

"There is little change from yesterday," he said.

Redoubt is 50 miles west of Kenai and 100 miles southwest of Anchorage. It last erupted over a five-month period from December 1989 through April 1990, dusting Anchorage with ash.

The continued eruption warning prompted city officials to send out information about dealing with volcanic ash. They urged residents to prepare ahead by outfitting homes with a supply of respirators, extra food, water and other supplies. They also encouraged stocking up on large plastic bags to cover appliances, extra air filters for cars, and windshield washer fluid.

During an ash fall, people and pets should remain indoors, they said.

In the last eruption, the ash plume disrupted air traffic and dumped ash on the city and other nearby communities.

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