Report on Pavlof (United States) — 29 August-4 September 2007
Smithsonian Institution / US Geological Survey
Weekly Volcanic Activity Report, 29 August-4 September 2007
Managing Editor: Sally Sennert.
Please cite this report as:
Global Volcanism Program, 2007. Report on Pavlof (United States) (Sennert, S, ed.). Weekly Volcanic Activity Report, 29 August-4 September 2007. Smithsonian Institution and US Geological Survey.
55.417°N, 161.894°W; summit elev. 2493 m
All times are local (unless otherwise noted)
Seismic activity at Pavlof fluctuated, but generally remained elevated during 29 August-4 September. A strong thermal anomaly was present at the summit on satellite imagery during 29 August-2 September; clouds inhibited observations on 3 and 4 September. Based on pilot reports and observations of satellite imagery, ash plumes rose to altitudes of 2.4-4.9 km (8,000-16,000 ft) a.s.l. during 28-30 August and drifted SSE and SE. On 30 August, National Weather Service observers in Cold Bay (about 60 km SW) reported that a plume rose to an altitude of 6.1 km (20,000 ft) a.s.l. and produced lightning. Based on satellite imagery, AVO reported that steam-and-ash plumes rose to altitudes of 6.1 km (20,000 ft) a.s.l. on 31 August. The Volcanic Alert Level remained at Watch and the Aviation Color Code remained at Orange.
Geological Summary. The most active volcano of the Aleutian arc, Pavlof is a Holocene stratovolcano that was constructed along a line of vents extending NE from the Emmons Lake caldera. Pavlof and Pavlof Sister to the NE form a dramatic pair of symmetrical, glacier-covered stratovolcanoes that overlook Pavlof and Volcano bays. Little Pavlof is a smaller cone on the SW flank of Pavlof volcano, near the rim of Emmons Lake caldera. Unlike Pavlof Sister, eruptions have frequently been reported from Pavlof, typically 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 recorded 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.