Redoubt volcano exploded twice on Thursday, sending a black cloud of ash east over the Kenai Peninsula and forcing commercial airlines to halt nearly all flights in Southcentral Alaska.
Following an initial blast at 8:34 a.m., a huge explosion 50 minutes later sent ash soaring 65,000 feet above sea level -- more than 12 miles high -- topping all prior eruptions since the Cook Inlet volcano burst to life Sunday night.
Alaska Airlines canceled all flights in and out of Anchorage for the rest of the day, saying it would reassess the situation this morning, and other airlines canceled or diverted flights as well.
No ash was expected to fall in Anchorage, but late in the day a "faint trace" was reported outside the Alaska Volcano Observatory on the Alaska Pacific University campus, AVO geophysicist Rick Wessels reported.
"Basically it was an immeasurable amount here," Wessels said.
Ash began coating Homer shortly before 2 p.m.
A purplish plume blocked the view across Cook Inlet and the smell of sulfur wafted into town as the ash cloud advanced, City Manager Walt Wrede said.
Businesses closed early and the city sent workers home for the day, Wrede said. By 4:45, skies had cleared and a small sprinkling of ash covered the snow.
"I can see little blobs of snow that have blown up against the window," said Mary McBurney, the city manager's wife. "If you look really closely, you can see the little fine grains of volcanic dust in them."
The family pets were stuck inside.
"I took the dogs out for a quick pee just around noon when the ash advisory started, so I figured that they could probably last through the worst of it," McBurney said.
Ashfall was reported as far north on the Peninsula as Kasilof and as far south as Nanwalek.
On the Sterling Highway just south of Anchor Point, Pat Ligenza stood inside Blackwater Bend, her drive-through coffee shop, and watched two clouds roll in across the Inlet at midafternoon.
One of them was approaching from the south and the other from the north -- most likely one from each of the morning's eruptions, she guessed.
When they came together, the sky turned a yellow brown -- and ash rained down, sprinkling the cars of customers who came by for coffee.
"It's like everything's dirty," Ligenza said.
The sky darkened above Nanwalek around 1:30 p.m, said Charlemagne Active, a health aide at the local clinic. As the cloud moved in, the air became hazy and ash dusted the buildings, falling for about an hour.
The Weather Service released an ashfall advisory to aviators for an area that encompassed all of the Kenai Peninsula and parts of Prince William Sound -- as well as a portion of a major air route from Seattle to Anchorage.
Anchorage International Airport remained officially open.
Era Aviation placed all flights on hold, said vice president Mike LeNorman. The commuter airline canceled flights Thursday from Anchorage to Kodiak, Homer and Bethel and two flights from Anchorage to Kenai.
FedEx also canceled flights out of its Anchorage cargo hub, and rerouted or turned back flights to avoid the city.
By day's end, the usually bustling domestic terminal was a sleepy, lonely place. No one waited at the baggage claim or stood at the ticket counters. Footsteps echoed across the halls.
"It's a ghost town," said airport worker Shelley McCormick. "There's not one single aircraft at FedEx or UPS. Nothing."
At Elmendorf Air Force Base, training flights were scaled back and the Air Force sent several aircraft, including four fighter jets, to other Air Force bases.
"We definitely err on the side of caution because we have billions of dollars of aircraft," said Capt. Candice Adams.
After Redoubt's volcanic hazard status was downgraded to aviation color code orange Wednesday afternoon, the stratovolcano 100 miles southwest of Anchorage burst back to life with the 8:34 a.m. eruption, which sent an ash cloud 30,000 feet above sea level.
Following the second explosion at 9:24 a.m., a seismometer positioned on the ground east of the volcano's summit recorded the signal of a large mud flow, called a lahar, AVO geophysicist Stephanie Prejean said.
The Weather Service subsequently issued a flash flood warning for the Drift River, which connects the Drift Glacier on the east slope of Redoubt to Cook Inlet, 27 miles downstream.
Two AVO teams -- one in a helicopter, a second in a small plane -- flew from Anchorage to Mount Redoubt on Thursday afternoon to assess both the river and the volcano.
Unlike eruptions earlier this week, the explosions Thursday came without any short-term seismic warning, Prejean said.
That wasn't a total surprise, she said, since earlier this week the volcano figuratively cleared its throat and is now breathing freely.
"At this point we have a wide-open system, and so probably for most of the rest of the eruption we don't expect to see short-term warnings," Prejean said.
Whether this episode will last as long -- or longer -- than the four-month span of explosions that occurred during Redoubt's eruptive phase in the winter of 1989-1990 isn't clear, she said.
"We just don't know how much magma is down there that needs to get out."