Mount Redoubt, a volcano 100 miles southwest of Anchorage, is rumbling and simmering, prompting geologists to warn that an eruption may be imminent. Scientists from the Alaska Volcano Observatory have been monitoring activity round-the-clock since the weekend.
On Thursday, the observatory said: "Seismicity remains above background and largely unchanged with several volcanic earthquakes occurring every hour." The last time the 10,197-foot peak blew was during a five-month stretch starting in December 1989. It disrupted international air traffic and placed a layer of volcanic dust throughout the Anchorage area.
"The level of seismic activity" has "increased markedly" in recent days at the 10,197-foot peak located about 100 miles southwest of Anchorage, the state's most populous city, according to the Alaska Volcano Observatory. "We don't have a crystal ball," said Peter Cervelli, a research geophysicist with the observatory, which is aggressively monitoring the volcano. But "we expect based on the past behavior of this volcano that this activity is going to culminate in an eruption." The activity has consisted "of a combination of discrete, relatively small earthquakes and periods of more continuous volcanic tremor," Cervelli said.
Scientists raised the alert status Sunday to a "watch" level, the second-highest, based on seismic activity detected January 23. The "watch" status means the "volcano is exhibiting heightened or escalating unrest with increased potential of eruption, time frame uncertain, or eruption is under way but poses limited hazards," according to the U.S. Geological Survey.
Maureen Burke, 29, a coffee shop manager in Anchorage, said she remembers the last eruption and isn't too worried this time. She said living in Alaska and being close to nature, residents just laugh such events off, dealing with them as they come. Falling ash is a potential problem. The best way to protect yourself from the harmful showers of ash is to wear a mask, Missy Moore, 33, said.
Volcanoes in Alaska, including Redoubt, typically erupt explosively, shooting ash almost eight miles high. Volcanic ash features small, jagged pieces of rock and glass. This differs from volcanoes in Hawaii, which usually have slow rolling lava ooze out. The difference is gas trying to escape gets blocked, possibly by a lava dome or a viscous magma that increases the power from beneath, said observatory geologist Jennifer Adleman. "Its pressure keeps building and building," she said.
Depending on wind, the ash plume could be pushed straight at Anchorage, the state's largest city. This has prompted state and city officials to post bulletins on how to deal with the ash. Tips include staying inside, wearing a mask or wet bandanna if going outside and wearing goggles over contact lenses.
s an administrator and supervisor of Starbright Early Learning Center in Anchorage, Moore said, "it's really not anything to worry about just yet."
If Mount Redoubt covers nearby cities with ash, Moore said the school will adhere to the public school district's guidelines.
"If the [public] school district closes schools, our school closes too. The city of Anchorage advises citizens to stay indoors," Moore said. "The ash can get into your engines and mess up your car."
Shana Medcoff, 17, a barista in Kenai, about 50 miles from the volcano, said residents are encouraged to buy air filters for their cars.
Mount Redoubt last erupted nearly 20 years ago, in December 1989, and that lasted until April 1990. Geologists think there could be an eruption "similar to or smaller than the one that occurred in 1989-90." Learn more about Redoubt and its history »
That eruption spread ash in Kenai and Anchorage, where it disrupted air traffic operations. Cervelli said the ash plumes caused engine failure on a jet.
"It's not the closest volcano to Anchorage," Cervelli said, but "it has the potential to disrupt air traffic at Anchorage."
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The 1989-90 volcano also spurred volcanic mudflows, or lahars, that flowed east down the Drift River. The ash fall was seen as far away as Fairbanks and the Yukon Territory border.
The observatory has set up a Web camera near the summit of the volcano and another within Cook Inlet. It plans to do continuous visual surveillance, measure gas output and analyze satellite and weather-radar data.
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