Report on Pavlof (United States) — 19 June-25 June 2013
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 19 June-25 June 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, 19 June-25 June 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 during 19-25 June the eruption at Pavlov continued; seismic tremor and occasional explosions were detected. Cloud cover prevented web camera views. During 19-20 and 24 June elevated surface temperatures detected in satellite images were consistent with lava effusion. A small ash plume from the summit vent was also detected in satellite image on 19 June, and possibly detected during 20-22 June.
At 2250 on 24 June seismicity increased and became the strongest seismic activity detected so far during 2013. The seismicity was characterized by continuous intense tremor and frequent small explosions likely associated with lava fountaining and ash production. Seismicity remained high on 25 June. Satellite images and pilot observations indicated that a plume drifted W at altitudes as high as 8.2-8.5 km (27,000-28,000 ft) a.s.l. Satellite images also detected a strong thermal anomaly at the summit. Trace amounts of ash fell in King Cove, 48 km SW. The Volcanic Alert Level remained at Watch and the Aviation Color Code remained at Orange.
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.