Report on Pavlof (United States) — 27 July-2 August 2016
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 27 July-2 August 2016
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2016. Report on Pavlof (United States). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 27 July-2 August 2016. 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 on 28 July vigorous steam-rich gas plumes from Pavlof were visible in webcam images from Cold Bay (60 km SW) and Black Hills (35 km NNE). The report also noted that recent satellite images and a pilot observation indicated minor ash emissions associated with degassing which rose to an altitude less that 4.5 km (15,000 ft) a.s.l. The Aviation Color Code was raised to Orange and Volcano Alert Level was raised to Watch. On 29 July seismicity began to decrease. On 30 July minor steam emissions were visible in webcam images from Black Hills, and on 2 August a weak thermal anomaly was detected.
Geologic Background. 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.