Monitoring Alaska's volcanoes

Scientists plant mountaintop sensors to monitor activity, predict eruptions

Posted: Thursday, December 27, 2001

FAIRBANKS - Standing on top of 14,163-foot Mount Wrangell, Guy Tytgat took in the view. The Wrangell-St. Elias Range stretched out all around him.

The sky was cobalt blue. To the north was 16,237-foot Mount Sanford. To the southeast stood 16,390-foot Mount Blackburn.

Tytgat took in a deep breath - and almost gagged.

You see, the view from the top of Mount Wrangell is much better than the odor, if you happen to be standing in the path of the steam cloud that spews from the vent on the north crater of Alaska's tallest active volcano.

"Whenever the wind was blowing our way it stunk like heck," said Tytgat, a scientist for the Alaska Volcano Observatory who spent a day on the summit last summer putting in a seismic station to detect volcanic activity.

"It smells like rotten eggs," he said. "It's awful."

Mount Wrangell is the latest volcano to join Alaska's growing club of actively monitored volcanoes.

Wrangell Volcano, in the Wrangell-St. Elias National Park and Preserve about 250 miles south of Fairbanks, was added to the observatory's list of seismically monitored volcanoes on Nov. 30, bringing to 23 the number of active volcanoes being studied in Alaska.

 

"That's far more than any other volcano observatory in the world monitors," said scientist John Eichelberger with the observatory in Fairbanks, which is based in the University of Alaska Fairbanks' Geophysical Institute.

Since the Mount Redoubt eruption in 1989, which coated Anchorage with a blanket of ash and seriously disrupted air traffic over Alaska's largest city, the list of seismically monitored volcanoes has increased from four to 23.

"We now have about half the active volcanoes in Alaska monitored seismically," Eichelberger said.

There are about 40 historically active volcanoes in Alaska. On average, Alaska has one to two volcanic eruptions each year.

The sensors such as those installed on Mount Wrangell allow seismologists to predict, within a few days, when an eruption will occur. For example, seismologists alerted people two months before Mount Spurr southwest of Anchorage erupted in 1992, covering the city with ash. When Mount Redoubt blew in 1989, seismologists knew about 24 hours ahead of time that something was going to happen.

"We always get a few days warning," Eichelberger said. "We're usually able to say about a day ahead when something serious is going to happen."

The sensors, which detect earthquakes beneath the volcano, consist of a fiberglass hut about 5 feet tall and 5 feet wide. Seismic equipment inside is powered by a solar panel attached to the outside. Signals are transmitted to a receiving station in Tolsona and finally to the observatory via phone lines. A helicopter is used to transport the hut and equipment to the volcano.

Seismologists also analyze satellite photos of Alaska volcanoes daily for evidence of ash plumes and elevated surface temperatures.

 

The Alaska Volcano Observatory was established in 1988 after a volcano on Augustine Island in lower Cook Inlet blew ash eight miles into the sky and disrupted air traffic in Southcentral Alaska for several days.

The same thing happened two years later when Mount Redoubt south of Anchorage blew its top. It was during the Redoubt eruption that a passenger jet lost power when ash was sucked into its engines, though the crew was able to restore power before disaster struck.

"That was the slap in the face that volcanoes and ash in the air pose a major hazard to North Pacific air routes," said Tom Murray, a scientist for the U.S. Geological Survey who heads the observatory's Anchorage division.

An estimated 20,000 passengers a day fly over volcanoes in Alaska and those volcanoes emit ash into air routes an average of about five times a year, sometimes diverting international flights in the process, Eichelberger said.

"That's the single biggest reason we monitor volcanoes, because of the flight traffic," Eichelberger said. "It's not like we're in Japan where people are living right on top of volcanoes."

Since the Redoubt eruption, the observatory has received funding to monitor 20 active volcanoes in Alaska. Depending on where they are located, it costs between a half-million dollars to $1 million to equip a volcano with seismic monitoring stations.

This year, the observatory got $1 million to set up seismic stations on volcanoes in the western Aleutians. Seismologists have already begun putting instruments on Mount Veniaminof, an 8,225-foot volcano halfway out the Alaska Peninsula. Next year, they plan to set up seismic stations on Okmok Caldera, about 65 miles west of Unalaska.

"We're getting increasing pressure to do a better job of forecasting volcanoes," Murray said.

Volcanoes are evaluated for monitoring based on their proximity to population centers, international air routes and potential explosiveness, Eichelberger said.

Most volcanoes are monitored with six to eight seismic sensors. Wrangell has only four seismic stations because it is covered with so much ice that scientists have a hard time finding good places to anchor the huts.

Tytgat installed two seismic stations on Mount Wrangell in the summer of 2000, including one on top of the mountain. Two more were installed this summer. Murray waited until the final two stations were up and running before he added Wrangell to the list of actively monitored volcanoes in Alaska.

"I felt uncomfortable saying we were monitoring it with just two stations, especially since one was on the summit," he said. "You need at least four to eight stations to do a good job."

Wrangell Volcano is the only historically active volcano in the Wrangell volcanic field. The last, and only, recorded eruption was a small one in 1900, though residents in Glennallen can often see a steam cloud rising off the top of the mountain, Eichelberger said.

"Most of the active volcanoes in Alaska are in the Aleutian (Islands)," Eichelberger said. "The Wrangells are a separate group, kind of a big clump of volcanoes in the Southeast.

"They don't erupt very often but we have had some huge eruptions there in the last thousand years," he said.

Tytgat was half of a two-person team that put a station on the summit of Mount Wrangell last year, landing on top of the mountain in a helicopter. Going from sea level to 14,000 feet in the matter of an hour without being acclimatized is not easy.

"When you have to dig a hole and plant spikes in the ground it's hard to breathe," Tytgat said.

Among the supplies Tytgat and his co-worker, Hillary Fletcher, took to the top of the mountain last summer were oxygen tanks and a portable decompression chamber.

"If you're trapped up there because of weather and get mountain sickness it could be deadly," Tytgat said.



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