AVO reported that seismicity at Pavlof remained elevated during 21-28 September. Daily short-lived explosions from a vent on the upper SE flank were detected in seismic and infrasound data. Low-level ash emissions were visible in webcam images rising possibly several hundred meters above the summit during 21-23 September. Steam emissions rose from the vent during 24-25 September. The Volcano Alert Level and Aviation Color Code remained at Watch and Orange, respectively.

Geological Summary. The most active volcano of the Aleutian arc, Pavlof is a Holocene stratovolcano that was constructed along a line of vents extending NE from the Emmons Lake caldera. Pavlof and Pavlof Sister to the NE form a dramatic pair of symmetrical, glacier-covered stratovolcanoes that overlook Pavlof and Volcano bays. Little Pavlof is a smaller cone on the SW flank of Pavlof volcano, near the rim of Emmons Lake caldera. Unlike Pavlof Sister, eruptions have frequently been reported from Pavlof, typically Strombolian to Vulcanian explosive eruptions from the summit vents and occasional lava flows. The active vents lie near the summit on the north and east sides. The largest recorded eruption took place in 1911, at the end of a 5-year-long eruptive episode, when a fissure opened on the N flank, ejecting large blocks and issuing lava flows.

Source: US Geological Survey Alaska Volcano Observatory (AVO)