It has erupted at least 29 times since 1775. The most recent eruptive period occurred in April-May 1999. This information was summarized from a report on Global Volcanism Program. Since June of 1999, small low-frequency seismic events have been present at Shishaldin Volcano. These events have increased in amplitude over the last week.
Seismic data shows the presence of small phreatic explosions.
This information was summarized from a report on Global Volcanism Program. Lava was seen on the summit on April 18, and snowmelt was running down the northwest flank. An explosive eruption then occurred at Shishaldin on April 19, sending an ash plume 45,000 ft into the air. This event lasted about seven hours. Additional eruptions could occur with little or no warning, so the concern code has been raised to Red.