Observatory lowers Shishaldin Volcano alert to green but says it will erupt again

The Alaska Volcano Observatory lowered Shishaldin Volcano to green and normal on Monday, Nov. 2, the lowest level on its alert scale. The change ends more than 14 months at yellow and advisory for the Unimak Island peak, which at 9,373 feet is the highest in the Aleutian Islands.

The observatory defines green and normal as a volcano in its typical background, noneruptive state, or back in that state after a higher level.

"Current activity is near background for this volcano, and does not indicate increased likelihood of an eruption," the observatory said in its volcanic activity notice Monday. The same notice said future eruptions can come "with little to no warning." In a news item Tuesday, the observatory said Shishaldin "will erupt again."

This is the second downgrade since the 2023 eruption. The observatory first returned Shishaldin to green on Aug. 30, 2024, then raised it to yellow again on Aug. 25, 2025, citing rising sulfur dioxide, a more vigorous vapor plume and more earthquake and sound signals.

Monday's notice said the unrest began with rising sulfur dioxide, tremor (continuous low-level earthquakes) and infrasound, sound too low for people to hear, consistent with explosions deep in the vent. Activity peaked through June 2026, with signals consistent with magma rising to shallow levels. A four-month decline since then fits magma withdrawing deeper, the observatory said. No lava or eruption was seen at the surface.

The observatory's webcam image from Tuesday showed a vigorous summit steam plume. Such plumes can continue for decades, the observatory said. Unstable upper slopes left by the 2023 eruption can also collapse and raise small dust and ash plumes without any new eruption.

False Pass sits 23.4 miles from the volcano, Cold Bay 57.8 miles and King Cove 69.3 miles. Trace ash reached all three communities and Sand Point in 2023, according to the observatory's eruption record, and Cold Bay's airport closed from Sept. 25 to 29 that year because of ash on the runway. The Aleutians East Borough's draft hazard plan update said False Pass had ashfall for several months in 2023 and that a 1946 eruption covered the community in more than 2 inches of ash.

Shishaldin has had at least 54 episodes of unrest and more than 28 confirmed eruptions since 1824. Most are relatively small, but the 1999 and 2023 eruptions sent ash up to 46,000 feet above sea level, the observatory says.

The observatory will raise the alert again if signs show magma rising to shallow levels or an eruption begins.