Report on Pavlof (United States) — 4 June-10 June 2014

Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 4 June-10 June 2014
Managing Editor: Sally Kuhn Sennert

Please cite this report as:

Global Volcanism Program, 2014. Report on Pavlof (United States). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 4 June-10 June 2014. Smithsonian Institution and US Geological Survey.

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Pavlof

United States

55.417°N, 161.894°W; summit elev. 2493 m

All times are local (unless otherwise noted)


AVO reported that the Strombolian eruption at Pavlof continued during 3-10 June. On 3 June the FAA webcam showed a high steam plume rising above a vent on the NE flank and lower-level ash from pyroclastic flows on the N flank. During 3-4 June seismicity remained unchanged and persistent elevated surface temperatures were detected in satellite images. A steam plume with minor amounts of ash but rich in sulfur dioxide drifted 100 km W. Incandescence from lava fountaining was visible in webcam images on 4 June. According to a news article, flights in and out of Cold Bay and Unalaska were canceled on 4 June, affecting about 200 people.

Two strong explosions were detected by the seismic network at 0205 and 0245 on 5 June. Lightning was detected by the World Wide Lightning Location Network indicating the presence of ash; satellite images did not detected ash above the meteorological cloud tops at about 8.5 km (28,000 ft) a.s.l. A third event was detected at 0844. The level of activity declined during 5-6 June; ash emissions appeared to be greatly reduced although cloud cover continued to obscure satellite views. Elevated surface temperatures were observed in mostly cloudy satellite images during 8-9 June. The Aviation Color Code remained at Orange and the Volcano Alert Level remained at Watch.

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.

Sources: US Geological Survey Alaska Volcano Observatory (AVO), Alaska Public Media