Updated 4:15 p.m. 1/07/20
Ash eruption at Shishaldin Volcano continues and has intensified as shown in satellite and lightning data. The Aviation Color Code has increased to "red" and Alert Level has increased to "warning."
Hans Schwaiger, a geophysicist with the Alaska Volcano Observatory, said the volcano - 58 miles southwest of Cold Bay – began erupting again this morning, and had sent an ash cloud 27,000 feet that is drifting to the east-northeast, as of 1 p.m.
"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 and the National Weather Service issued a SIGMET warning. According to the AVO, RavnAir Group cancelled flights out of Cold Bay today because of ash fall.
"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 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. It has had at least 54 episodes of unrest, including over 24 confirmed eruptions, since 1775.
"Shishaldin has been one of the volcanoes that has been active over the last many decades," said Schwaiger. "In the late 1990s there was an eruption that sent a plume quite high, and then it was quieter for a while. 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."
Shishaldin is monitored by local seismic and infrasound sensors, satellite data, a web camera, a telemetered geodetic network, and distant infrasound and lightning networks.
The AVO said it is possible for the current activity to intensify or decrease with little warning.