Report on Pavlof (United States) — 22 September-28 September 2021
Smithsonian / US Geological Survey Weekly Volcanic Activity Report,
22 September-28 September 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, 22 September-28 September 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 21-28 September. Daily short-lived explosions from a vent on the upper SE flank were detected in seismic and infrasound data. Low-level ash emissions were visible in webcam images rising possibly several hundred meters above the summit during 21-23 September. Steam emissions rose from the vent during 24-25 September. 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.