“For some reason we can’t explain, it picked up in intensity and vigor,” said Tina Neal, an Alaska Volcano Observatory geologist.

The U.S. National Weather Service issued an ash advisory for the area around the Alaska Peninsula, about 600 miles southwest of Anchorage, where Pavlof is located.

Ash dusted nearby King Cove, but the plume of volcanic debris did not reach an altitude high enough to interfere with trans-Pacific jetliner routes.

Pavlof has erupted about 40 times since Russia colonized Alaska in the 1700s.

Meanwhile, Veniaminof volcano continued to spew smaller quantities of ash into the sky about 100 miles closer to Anchorage in activity that began last week.

Cleveland volcano is also on alert in the Aleutian Islands as it remains restless, but not emitting any lava or ash.

Photo: Theo Chesley