Report on Pavlof (United States) — 29 September-5 October 2021
Smithsonian / US Geological Survey Weekly Volcanic Activity Report,
29 September-5 October 2021
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2021. Report on Pavlof (United States). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 29 September-5 October 2021. Smithsonian Institution and US Geological Survey.
55.417°N, 161.894°W; summit elev. 2493 m
All times are local (unless otherwise noted)
AVO reported that seismicity at Pavlof remained elevated during 29 September-5 October. No explosions were recorded most days by the seismic and infrasound networks, and no eruptive activity was observed in mostly cloudy webcam and satellite images. On 3 October webcam images showed that recent ash deposits on the flanks had been covered by fresh snow; later that night either new ash deposits were visible in webcam images or older deposits were revealed due to snowmelt. Weakly elevated surface temperatures were identified in satellite images. At least two minor explosions were recorded during 4-5 October and minor emissions likely comprised of steam and sulfur dioxide were visible in morning webcam images on 5 October. 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 2519-m-high Holocene stratovolcano that was constructed along a line of vents extending NE from the Emmons Lake caldera. Pavlof and its twin volcano to the NE, 2142-m-high Pavlof Sister, form a dramatic pair of symmetrical, glacier-covered stratovolcanoes that tower above Pavlof and Volcano bays. A third cone, Little Pavlof, is a smaller volcano on the SW flank of Pavlof volcano, near the rim of Emmons Lake caldera. Unlike Pavlof Sister, Pavlof has been frequently active in historical time, typically producing 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 historical 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.