Alaska's Mount Redoubt has simmered down after spreading a layer of gritty volcanic ash over several communities, including the state's largest city.
The volcano was emitting low-level tremors Sunday but hadn't erupted, monitors at the Alaska Volcano Observatory said. A plume rose 25,000 feet (7,620 meters) above sea level, but scientists said it appeared to be only vapor and they were not adding it to Redoubt's 18 eruptions during the past week.
The calm follows several strong eruptions Saturday that spewed an ash cloud 100 miles (160 kilometers) northeast to Anchorage, the state's largest city, and beyond.
Ted Stevens Anchorage International Airport shut down because of the ash, which can cause dangerous damage to engines. Crews were cleaning up runways and passenger gates on Sunday, and one of the airport's three runways opened in the early afternoon, said airport spokeswoman Linda Bustamante. The airport is expected to be in full operations by Tuesday evening.
"The idea is to spread snow on top of the ash, get an ash-and-snow mix, then go out with graders with big blades in front, plow and truck the snow out," she said. "This is quite a cleanup going on."
Alaska Airlines, the state's largest carrier, canceled all flights in and out of Anchorage Saturday after the airport was shut down. Spokesman Paul McElroy said Sunday that the airline would inspect the runway and surrounding areas before deciding when to resume flights.
Nikiski, about 50 miles (80 kilometers) from Redoubt, was among the worst hit communities. Observatory volcanologist Game McGimsey said the ash accumulation there was as thick as a dime.
The volcano last erupted in 1989-90. A 1989 eruption sent ash 150 miles (250 kilometers) away into the path of a KLM flight carrying 231 passengers, flaming out its four engines. Pilots ultimately restarted the engines and landed safely.
The latest activity has caused flooding and mud flows into the Drift River valley, where the Chevron-operated Drift River Terminal is located. The terminal has 6.2 million gallons of oil stored in two tanks.