Aleutian Volcano Sees First Major Eruption Since 1974

May 26, 2021

Great Sitkin eruption column, as seen from Adak on May 25.
Credit Courtesy of Finn Spitler

Scientists have downgraded the alert level at Great Sitkin Volcano near the Aleutian Island of Adak following an eruption Tuesday night. 

The event took place at around 9 p.m. and produced an ash cloud up to 15,000 feet above sea level and impacted flights. 

"The eruption itself occurred for over about a minute," said David Fee, coordinating scientist for the Alaska Volcano Observatory (AVO). "It had a very loud, audible and low frequency sound to it. I guess a good analogy would be if you shake up a bottle and then you pop the cork and get an explosion out the top. That's kind of what happened here." 

Following the eruption, Fee said, they issued a red alert warning for planes in the area, because there was likely a high emission of volcanic ash in the atmosphere. 

Since then, activity has decreased at the volcano.

Steaming at Great Sitkin, seen from White Alice seismic station on May 20.
Credit Courtesy of Malcolm Herstand (AVO/DGGS)

"We lowered the advisory back down to orange this morning," Fee told KUCB Wednesday morning. "And there hasn't been much activity —  I think it's mainly just steaming since the eruption last night."

According to Fee, the activity at Great Sitkin isn't "normal," but it's also not unexpected, given some small explosions that have happened there over the past few years. 

He said the AVO will continue to watch closely for increased seismic activity or gas emissions that could indicate another eruption, but for now, it's pretty quiet. 

"We haven't seen an eruption like this from Great Sitkin at least as long as I've been around here," he said. "So it could quiet down or we could expect continued activity. We'll just have to wait and see." 

This is the first significant explosion at Great Sitkin since 1974.