Report on Pavlof (United States) — 3 November-9 November 2021
Smithsonian / US Geological Survey Weekly Volcanic Activity Report,
3 November-9 November 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, 3 November-9 November 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 the eruption at Pavlof continued during 3-9 November and was focused at a vent on the upper NE flank. Seismicity remained elevated; several small explosions and discontinuous tremor were recorded during 5-8 November with increased frequency compared to the previous week. The explosions likely produced small, low-level ash plumes, though weather clouds often prevented confirmation by satellite and webcam images. Elevated surface temperatures were visible in satellite images overnight during 7-8 November, coincident with the emplacement of a 30-m-long lava flow. Small diffuse ash plumes were visible in webcam images and dissipated quickly. Elevated surface temperatures remained visible through 9 November. 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.