Update: Mount Redoubt erupted again at 1:20 a.m., sending a cloud 50,000 feet into the atmosphere, the Alaska Volcano Observatory reported. An ashfall advisory for an area to the north and west was issued but expired at noon. No ash is expected in Anchorage. Airlines are operating normally.
Redoubt volcano teased air travelers Friday afternoon after a string of eruptions the previous night and morning, calming just long enough to get airlines flying again only to erupt once more at 5:35 p.m. Two more eruptions followed, 7:25 p.m. and 11:20 p.m.
It's a vexing pattern that scientists from the Alaska Volcano Observatory said is likely to continue for several months, based on the record of the volcano's last eruption cycle nearly 20 years ago.
The active volcano, one of four in the Cook Inlet area, is about 100 miles southwest of Anchorage and directly across the Inlet from Kenai, situated in a location where it can disrupt flights to and from Anchorage when belching ash.
The observatory reported that the first afternoon eruption sent ash rising to 40,000 feet based on radar observations from the National Weather Service. The second shot ash to 51,000 feet. The third sent ash 40,000 feet.
The latest eruptions prompted the National Weather Service to extend an earlier ashfall advisory to 7 a.m. today for the eastern areas of the upper Kuskokwim Valley, including Aniak and McGrath. Only small accumulations were expected -- from a trace to about an eighth of an inch -- as the ash drifted north along the Alaska Range.
No significant ashfall was anticipated in Anchorage.
In the minutes after the first eruption, airline officials were trying to decide how to respond.
"It's very fluid," said Paul McElroy, a spokesman for Alaska Airlines. "We'll fly as long as it's safe to do so."
Earlier, Alaska Airlines had plans to start flying into the Anchorage international airport again on a limited basis after another round of volcano eruptions interrupted morning air travel.
Meanwhile, the Drift River oil terminal, downriver from the volcano, was unaffected by a flood of water and mud unleashed by an eruption Thursday morning, volcano observatory scientists said at a news conference Friday afternoon. The water level didn't rise as high as it did Monday, when mud lapped over the top of a protective dike, said hydrologist Chris Waythomas.
More than 6 million gallons of crude is stored in two tanks at the terminal, a way station for Cook Inlet oil destined for the Tesoro refinery near Kenai. Coast Guard Cmdr. Joseph Losciuto, the federal on-scene coordinator in the event of an oil spill, said at the news conference that a sounding of the offshore dock near the terminal shows it's still deep enough and debris-free for a tanker to tie up and take on oil.
Federal, state and oil company officials are still discussing how to proceed, Losciuto said. A tanker had been scheduled to arrive during the first week of April, and Tesoro needs oil for its refinery, they said. But the terminal was evacuated Monday and hasn't been operated since.
If oil can be safely loaded, Cook Inlet Pipeline Co., a Chevron-operated firm, could reduce the amount of stored oil to about 1.7 million gallons in each tank, the minimum needed to weigh them down in the event of a flood, Losciuto said. Other options include resuming operations if it's safe, and completely draining the tanks and replacing the oil with water for ballast, he said.
For the moment, the safest alternative is to leave the minimum in the tanks, Losciuto said. Until the terminal can be operated again, oil is being stored on the platforms themselves and at two other storage and processing facilities on the west side of the Inlet. When room runs out in about 10 days, the platforms will have to start shutting down, he said.
With only minimal ashfall reported over Southcentral Alaska since the current eruption cycle began Sunday, the biggest disturbance to normal activity has been to air travel. Alaska Airlines canceled 28 flights on Friday, and has canceled more than 150 flights since the weekend, inconveniencing an estimated 10,000 passengers, said Bobbie Egan, an airline spokeswoman.
Alaska Airlines had mostly returned to normal Friday, except for flights to Nome and Kotzebue, which have been canceled because of the ash cloud's movement north, the airline said. Smaller airlines, including PenAir and Era Aviation, resumed flying as well, according to Linda Bustamante, an airport spokeswoman. Many Friday night flights on Continental, Delta, USAirways and Northwest were canceled even before the evening eruptions, she said.
The volcano also slowed deliveries and passenger flights connecting Alaska's biggest cities and smallest villages.
At this time, we're waiting for at least 20,000 pounds of bypass (mail)," said Jane Cofsky, station manager for Yute Air in Bethel.
That includes groceries the airline delivers to villages across the Yukon-Kuskokwim Delta.
"It would have arrived had it not been for the volcano," she said.
Earlier in the week, delays kept Iditarod mushers in Nome for an extra two days, said race public relations director Chas St. George.
Ash can cause severe and sudden damage to jet engines and other mechanical devices. During Redoubt's last eruption cycle 19 years ago, a KLM jetliner lost power to all four engines when it passed through an ash cloud over Alaska. Despite ash that made it nearly impossible to see anything in the cockpit and cabin, the pilots restarted the engines and brought the craft safely down for an emergency landing in Anchorage. The plane, its paint sanded off and hydraulics ruined, was a total loss.
As flights were canceled and long-anticipated vacation plans got postponed, more Alaskans were phoning the Alaska Volcano Observatory Thursday and Friday, asking: How much longer is this thing going to last?
The official AVO reply, posted on its Web site: "The current Redoubt eruption is expected to continue for weeks to months."
That's an admittedly non-specific response, based partly on history and partly on current observations, the observatory's Waythomas explained Friday.
If history is a guide, the last eruption at Redoubt -- from December 1989 to April 1990 -- lasted four months and generated 23 distinct eruptions, according to U.S. Geological Survey records.
Before that, an eruptive episode begun in 1965 dawdled on for a couple of years, but there were no instruments on the volcano back then to record mini-tremors or changes in its shape like today, so it's difficult to make scientific comparisons. That leaves just the 1989-90 eruption cycle as a historical clue, Waythomas said.
"That's a sample size of one," Waythomas said, citing the weakness in interpreting the statistics.
By comparison, Redoubt's current eruptive episode is less than a week old, and it would have to continue through half the summer to match the 1989-1990 eruption in terms of duration. At the same time, it's already generated 13 distinct eruptions, and at that rate it could match its previous mark in just one more week.
Observatory scientists were hoping to view Redoubt's summit during a Thursday fly-by field trip to assess changes near the vent, but cloud cover hid it from view.
Below the summit, however, Waythomas and others discovered that heat from the volcano has already melted or evaporated away about one-fifth of the Drift Glacier. That's nearly commensurate with the "cubic kilometer ... about one-fourth of the glacier" that was lost to melting 20 years ago, Waythomas said.
"So perhaps this eruption is not going to follow that (1989-90) script," he said. "It's still too early to tell."
This story was written by Richard Mauer and reported by Mauer, George Bryson, Julia O'Malley and Kyle Hopkins. They can be contacted at email@example.com, firstname.lastname@example.org, email@example.com and firstname.lastname@example.org.