Pain in the ash?: Mount Redoubt's messy reminder may have an upside

Posted: Monday, April 06, 2009

Mount Redoubt doesn't have to be a total pain in the ash.

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Photo By Aaron Selbig/Homer News
Photo By Aaron Selbig/Homer News
A surfer wears a surgical mask for protection from ashfall while catching a wave on Kachemak Bay at 1:30 p.m. Saturday.

The plumes of pulverized magma belched out by the volcano can take down airliners, destroy motors, scratch your car, fill your house and damage lungs among many other things.

While the short-term impacts of an ash cloud passing over the central peninsula will likely be less than pleasant, a few positives may come out of an ashfall.

Most notable among the benefits of ash is the boost it can give to plant life.

"It's funny; I was just talking to some hay growers who were saying the best crops they ever had was when Redoubt last erupted," said Stephen Brown, the Division of Agriculture's district agent in the Matanuska-Susitna valleys.

Brown said he had heard similar remarks from farmers on the peninsula as well.

Dr. David Valentine, an associate professor of forest soils at the University of Alaska Fairbanks, said that when the magma is blown out of a volcano, it rapidly cools, trapping minerals within.

The rapid cooling gives volcanic ash its glass-like consistency.

While its abrasive qualities make it a peril to lungs, windshields and internal combustion engines, it also means the ash breaks down very easily.

"Depending on what's in that body of magma that produced the ash, those minerals can weather out relatively quickly," he said.

The minerals and nutrients are released and absorbed, enriching the soil.

John Power, a geophysicist with the Alaska Volcano Observatory in Anchorage noted that some of the richest soils in the world are located near volcanoes.

"Some of the richest agricultural lands in Central America and Africa are close to volcanic centers," he said.

Everything comes in moderation however, Brown said.

"Ash repels water. If you get a thick coat, (water) runs off," he said.

Valentine also noted that ash has properties that can reduce the productivity of soils.

He explained that the allophane, a mineral present in ash, can bind up phosphorous, a key nutrient needed for plant growth. If too much is released, plants will suffer.

Ash isn't just good for plants however.

Ceramics artists have been known to incorporate ash into their glazes.

Ida Cockroft, a local potter, said she used ash deposited from the last Redoubt eruption during its outbursts starting in 1989 through '90.

More recently, she and other peninsula artists have incorporated the ash blown out by Mount Augustine into their work.

"When Augustine went off people were gathering it in the snow and letting it melt and giving me ashes from that and from sweeping it off their porches," she said.

Cockroft said she still has a pail of ash she got from the eruption of Mount Saint Helens in 1980.

"The ash makes mostly a red brown and green glaze because of iron content and manganese," she said.

She said she only uses the ash in a glaze on occasion, the colors aren't particularly appealing and it can be difficult to use.

"As you know it's dusty. If you put just this on as a glaze you have to add something like a binder to hold it in place," she said. "There's several different formulas that we have that can be used."

The fine particulates drifting through the atmosphere can also enhance the beauty of sunset and sunrise, not that this area needs much additional help.

Power said he didn't know if Redoubt's eruptions were putting out enough volume to make noticeable changes, though.

"Following the eruption of Krakatoa in 1883, there were nice sunsets reported in England," Power said, referring to the one of the largest volcanic eruptions in modern times on a small Indonesian island. "Redoubt's eruptions aren't that big."

Power said historically, ash has also been incorporated into pumice for industrial processes as well.

Ash's abrasive qualities make it ideal for smoothing out surfaces to a degree that other materials can't. Power said that it had been used in applications such as the refinement of cylinder chambers for race car engines in the past, though he didn't know if that was still the case.

"There's also been areas of world where they've used volcanic pumice to make stonewashed jeans," he said.

The ash was mined from the side of volcanoes where it could be collected bountifully.

Don't jump to start a new business venture though; Redoubt nor its sister volcanoes will likely supply enough.

"I wouldn't expect anyone in Alaska to do this, there's much better places in the world to get pumice," he said.

Dante Petri can be reached at

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