Alaska Volcano Observatory

On May 12, 2026, citing increased seismic and gas activity at Kupreanof volcano, AVO raised the Aviation Color Code and Volcano Alert Level at Kupreanof volcano from UNASSIGNED to YELLOW/ADVISORY.

From the May 12, 2026 Volcano Activity Notice: "Seismic activity and volcanic gas emissions increased over the past few months and now continue at elevated levels at Mount Kupreanof. This activity is likely caused by a magmatic intrusion beneath the volcano. The Alaska Volcano Observatory (AVO) is therefore increasing the Aviation Color Code to YELLOW and the Volcano Alert Level to ADVISORY in response to this sustained volcanic unrest. 

"Summary of activity and hazards
Seismicity was first detected in February 2026 and has increased in recent months, with earthquakes as large as magnitude 3.1 detected.
Sulfur dioxide (SO2) emissions were detected beginning on April 4 with emission rates of ~100 to 1,000 tons per day, which are well above the background rate of <100 tons per day.
These signals likely indicate a magmatic intrusion beneath Mount Kupreanof.
AVO is therefore increasing the Aviation Color Code to YELLOW and the Volcano Alert Level to ADVISORY in response to this sustained volcanic unrest.
Data do not suggest an eruption is imminent and further signs of increased unrest would be expected prior to eruption.
There is no local monitoring network at Mount Kupreanof. Seismicity is detected using only regional stations, which limits detection of smaller events (magnitudes <2) and results in large location errors."