ANCHORAGE, Alaska >> An Alaska volcano eruption is prompting regional airlines to cancel flights to nearby communities, including a town that reported traces of fallen ash.

Pavlof Volcano released ash plumes as high as 22,000 feet over the weekend, according to the Alaska Volcano Observatory. Clouds obscured the volcano Monday, but U.S. Geological Survey scientists said seismic instruments at the volcano show continuing tremors.

"Seismically, it’s been pretty steady over the last 12 hours," geologist Chris Waythomas said late this morning.

The abrasive ash has not risen enough to threaten international air traffic passing over the volcano-rich Aleutian arc, Waythomas said. Ash emissions have gone high enough, however, to affect flights of some smaller planes.

Anchorage-based regional carrier Penair has canceled a dozen passenger and cargo flights to several remote communities since Sunday afternoon. The communities include Sand Point, which reported a dusting of ash Sunday.

Penair CEO Danny Seybert said for those flying in the region, flight disruptions are part of doing business. It’s not unusual for the airline to cancel flights a couple times each year because of volcanoes, according to Seybert. To him, it’s not a big deal, not a sky-is-falling crisis.

"If we had that attitude, we would have quit 50 years ago," he said. "It’s one of the situations that Mother Nature presents itself along our route structure."

Ace Air Cargo, also based in Anchorage, canceled two flights and delayed others, but for the most part, its planes are flying around any ash, said Greg Hawthorne, a company official. The airline is closely monitoring developments, he said.

"We’re used to those volcanoes going off in that region," he said. "But if the winds are wrong, you don’t want to test that pumice."

Pavlof eruptions typically involve gas-rich fountains of lava that can shoot up to a few thousand feet. But its ash clouds are usually lower and less dense than the plumes of more explosive volcanoes that pose a greater hazard to aircraft, according to scientists. That’s not to say it couldn’t spew out much higher plumes, they said.

The volcano 625 miles southwest of Anchorage is among the most active volcanoes in the region, with nearly 40 known eruptions, according to the observatory.

Pavlof last erupted in 2007. During the 29-day eruption, the volcano emitted mud flows and erupting lava, as well as ash clouds up to 18,000 feet high.

In the most recent eruption, trace amounts of ash fell at both Nelson Lagoon and in Sand Point, a town about 55 miles from Pavlof. Residents in the community of nearly 1,000 awoke Sunday to a thin layer of the gritty ash.

Kathleen Harper, a National Weather Service observer based at Sand Point, said it was raining lightly Monday. But on Sunday, ash was in the air, irritating her eyes and the back of her throat. She said the ash fall amounted to about a half teaspoon per hour on a sheet of white paper she placed on the ground.

When the weather is clear, the eruption can be seen from Sand Point, as well as the community Cold Bay, 37 miles from Pavlof. Through her binoculars, Harper saw Pavlof spit out a fountain of rocky lava.

"You could actually see the rocks coming out of the volcano," she said. "It was pretty cool."