On Sunday afternoon, one of the most active volcanos in Alaska's Aleutian arc, Mount Pavlof, began erupting and, in the process, sent an ash cloud 20,000 feet into the air. As the Associated Press reports, this follows on an earlier eruption in 2013 that sent up an ash cloud 27,000 feet high, and per Forbes and Wikipedia, it erupted again in mid-2014 sending ash up to 35,000 feet. The main impacts from this remote volcano's eruptions are aviation-related, and the tweets below from Sunday afternoon shows Pavlof's ash cloud already spreading among the clouds.

The eruption began at 4:18 p.m. local time and is ongoing.

Mount Pavlof has erupted more than 40 times since eruption records have been kept, including in 1980, 1981, 1983, 1986-1988, 1996-1997, 2007, 2013, and 2014. Its longest recent period of dormancy was 10 years, between 1997 and 2007.

The volcano is 592 miles southwest of Anchorage, and the nearest town, Cold Bay (pop. 108) is 37 miles to the southwest. Some may recall that a SFO-bound Delta Airlines flight from Tokyo had to make an emergency landing at Cold Bay in 2013 due to a mechanical problem — the town maintains Alaska's third longest runway, which was built as part of a US military outpost in World War II.

The Pavlof volcano has a nearby sister volcano that's actually named Pavlof Sister, but that one hasn't erupted since 1786.

A map of the Aleutian arc volcanoes, below.