Explosive eruption of Shishaldin could bring trace amounts of ashfall to Alaska Peninsula

Satellite data observations show the ash cloud reached 40,000 feet above sea level
Published: Oct. 3, 2023 at 9:02 AM AKDT
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ANCHORAGE, Alaska (KTUU) - One of the most active volcanoes in the Aleutian Arc erupted early Tuesday morning.

Satellite data at 5:20 a.m. AKDT showed an ash cloud from the explosive eruption reaching a height of 40,000 feet above sea level. The Alaska Volcano Observatory says this was followed by an increase in eruptive activity over a period of several hours. The area also experienced a sharp increase in infrasound, earthquakes, and lightning.

As the volcano remains active with significant ash emissions likely to continue over the next several hours, the Volcano Alert Level is being raised to “warning.” The Aviation Color Code is also being raised to RED, with the National Weather Service issuing an inflight weather advisory for the ash cloud.

According to the advisory, the ash plume is drifting south-southwest at a speed of roughly 25 mph.

Lava flow from Shishaldin Volcano

Ashfall is possible across Unimak Island, with trace amounts for the community of False Pass. Pyroclastic and mud flows are also likely on the immediate flanks of the volcano.

This increase in activity began around 9 p.m. Monday night when seismic activity at the volcano began to significantly increase. According to the observatory, around the same time, satellite images showed surface temperatures increase, which was confirmed via webcam images.

The lava flow Monday evening caused small hot avalanches of rock and lava down the slope of the mountain.

Shishaldin has been fairly active since July, with the two most recent eruptions sending ash plumes at or above 40,000 feet. Shishaldin has had over 26 confirmed eruptions since 1824, with most of them being fairly small. The spring 1999 event was among the larger ones, generating an ash cloud that reached 45,000 feet above sea level.