Report on Pavlof (United States) — November 1987

Scientific Event Alert Network Bulletin, vol. 12, no. 11 (November 1987)
Managing Editor: Lindsay McClelland.

Pavlof (United States) Dark ash plumes from near-summit vent

Please cite this report as:

Global Volcanism Program, 1987. Report on Pavlof (United States). In: McClelland, L (ed.), Scientific Event Alert Network Bulletin, 12:11. Smithsonian Institution. http://dx.doi.org/10.5479/si.GVP.SEAN198711-312030.

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Pavlof

United States

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

All times are local (unless otherwise noted)


The volcano had apparently been quiet for several weeks after new flank ash deposits were seen 4 September; it was inactive and covered with fresh snow on 20 September. A NOAA 9 satellite image on 30 September at 0525 showed a plume extending about 20 km S from Pavlof. Weather clouds obscured later activity.

Eruptions began again in mid-October and continued in November (table 4). Dark ash was steadily emitted to 250 m above the summit on the morning of 5 November. The next day wind blew ash down the SE flank for 120 m; the plume trailed about 30 km SE. Continued ash emission was observed on 6, 7, and 9 November. Plumes reached to 3.6 km altitude (~1 km above the summit) and drifted a maximum of 35 km from the volcano. During observations on 16 and 27 November only white steam was emitted.

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.

Information Contacts: J. Reeder, ADGGS; M. Matson, NOAA/NESDIS.