Report on Pavlof (United States) — 27 October-2 November 2021
Smithsonian / US Geological Survey Weekly Volcanic Activity Report,
27 October-2 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, 27 October-2 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 27 October-2 November and was focused at a vent on the upper SE flank, near the location of the 2007 vent. Seismicity remained elevated with tremor and daily small explosion signals. The explosions likely produced low-level ash plumes that rose no higher than 3 km (10,000 ft) a.s.l., though weather clouds often prevented confirmation by satellite and webcam images. Elevated surface temperatures were visible in satellite images during 25-26 October. A small plume and discolored snow at the summit were visible in mostly clear satellite images during 27-28 October. Slightly elevated temperatures were identified in satellite images during 31 October-2 November. Minor steaming at the vent was seen in webcam images on 1 November, as well as a small ash plume that rose to a low height and dissipated quickly. 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.