Report on Pavlof (United States) — 8 May-14 May 2013
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 8 May-14 May 2013
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2013. Report on Pavlof (United States). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 8 May-14 May 2013. 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 13 May seismicity at Pavlof increased at 0800 commensurate with the presence of an intense thermal anomaly at the summit observed in satellite imagery. Several spikes in seismicity occurred between 0900 and 1000. AVO noted that similar patterns of seismicity and elevated surface temperatures have previously signaled the onset of eruptive activity at Pavlof. Although not yet visually confirmed at the time of the report, a low-level eruption of lava had likely begun from a summit vent. No ash clouds were detected. The Volcanic Alert Level was increased Watch and the Aviation Color Code was increased Orange. On 14 May pilot reports and satellite images confirmed activity; a spatter-fed lava flow advanced about 0.5 km down the N flank. Minor steam-and-ash emissions from the summit were visible from Cold Bay (60 km SW).
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.