AVO reported that a minor eruption at a vent on Pavlof’s upper E flank was ongoing during 13-20 September. Seismic tremor persisted. New lahar and minor ash deposits extending less than 900 m from the vent were visible during 11-13 September. Strong incandescence at the vent and from an area within 200 m downslope was visible in webcam images starting on 14 September, signifying the emplacement of a short lava flow. Elevated surface temperatures over the vent and flow were identified in satellite images through 20 September; lava effusion continued but no active lava flows extended down the flank from the vent. Explosions were recorded during 18-19 September and steam emissions were visible in webcam images during 19-20 September. The Volcano Alert Level remained at Watch and the Aviation Color Code remained at Orange.

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)