Report on Pavlof (United States) — 1 December-7 December 2021
Smithsonian Institution / US Geological Survey
Weekly Volcanic Activity Report, 1 December-7 December 2021
Managing Editor: Sally Sennert.
Please cite this report as:
Global Volcanism Program, 2021. Report on Pavlof (United States) (Sennert, S, ed.). Weekly Volcanic Activity Report, 1 December-7 December 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 1-7 December, focused at a vent on the upper SE flank. Seismicity remained elevated and several daily explosions were detected using infrasound data. Elevated surface temperatures were observed in satellite data during 1-2 December, though cloud cover often prevented observations. No emissions were visible in mostly cloudy satellite and webcam views during 1-3 December. Minor ash emissions were visible in webcam images on 4 December and, based on webcam images and a pilot observation, the next day a diffuse ash plume rose as high as 3 km (10,000 ft) a.s.l. and drifted tens of kilometers beyond the volcano. 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.