Unrest at Aleutian volcano increases, triggering aviation warnings

Shishaldin Volcano in eruption, Jan. 6, 2020, as seen from Cold Bay, about 58 miles northeast of the volcano. (Photo courtesy of Aaron Merculief via Alaska Volcano Observatory)

Update (Wednesday, 5:28 p.m.) — Hope McKenney, KUCB-Unalaska

Seismic activity at Shishaldin Volcano is back down after an eruption Tuesday caused flights to be cancelled out of Cold Bay. The volcano has been active since July and has had two ash eruptions in the past week. (Read more.)

Original story

Ash eruption at Shishaldin Volcano in the Aleutian Islands has intensified, triggering aviation warnings in the region.

Hans Schwaiger, a geophysicist with the Alaska Volcano Observatory, said the volcano — 58 miles southwest of Cold Bay — began erupting again this morning, sending an ash cloud 27,000 feet in elevation that is drifting to the east and northeast as of early Tuesday afternoon.

“At about 5 a.m. this morning, there was an increase in the seismicity at Shishaldin,” said Schwaiger. “Seismicity then dropped a bit but has been ramping up recently. And since then, the high-level meteorological clouds have moved to the northeast, and we can see that there is a volcanic cloud that has been continuous, likely since that event this morning.”

The AVO alerted the aviation community about the potential hazard of volcanic ash in the atmosphere. There has been no impact on aviation thus far, but the National Weather Service issued a SIGMET warning.

Schwaiger said there is some ash fallout potential near the volcano.

“There’s possibly a little bit of trace ash that might fall in the coastal area to the north of the volcano,” said Schwaiger. “So the National Weather Service is putting out a marine advisory for that area. But at this point it doesn’t look like any communities will be impacted by the fallout. But the eruption is ongoing, so that could change if the weather or the winds change direction.”

The AVO said there are trace amounts of ash fall in Cold Bay.

The volcano had a low-level eruption last week that produced an ash cloud approximately 24,000 feet high, accompanied by volcanic lightning.

The AVO is monitoring the volcano closely, and while there are no indications of a major eruption, Shishaldin is a volcano with an ability to ramp up quickly. According to AVO, it has had at least 64 episodes of unrest, including over 24 confirmed eruptions since 1775.

“In the late 1990s there was an eruption that sent a plume quite high, and then (Shishaldin Volcano) was quieter for a while,” Schwaiger said. “But every few years it seems like it’s becoming a bit active. So we’re in the middle of an eruptive sequence right now, and it will likely continue for a bit. We don’t know for how long, but this isn’t anything outside of its normal behavior.”

The AVO said it is possible for the current activity to intensify or decrease with little warning.

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