Report on Pavlof (United States) — December 1975
Natural Science Event Bulletin, vol. 1, no. 3 (December 1975)
Managing Editor: David Squires
Pavlof (United States) Ash eruptions, lava emission, and orange glow
Please cite this report as:
Global Volcanism Program, 1975. Report on Pavlof (United States). In: Squires, D (ed.), Natural Science Event Bulletin, 1:3. Smithsonian Institution. http://dx.doi.org/10.5479/si.GVP.NSEB197512-312030.
55.417°N, 161.894°W; summit elev. 2493 m
All times are local (unless otherwise noted)
10 December, 0100-0800: black ash and numerous sporadic orange mud/lava bursts. 18 December, 1300: white steam. 19 December, 1000: grey smoke. 23 December, 1000: white steam; fresh snow on N slope was darkened from the ashfall. 23 December, 1900: 10-second orange glow. 27 December, 1000: white steam; snow was white except for ash on N slope. 28 December, 0815: Tephra ejection like "a blowtorch" visible (in daylight) for 30 seconds; 1300: grey smoke. 30 December, 1755-1810: energetically emitted surges of glowing red-hot ejecta. In contrast to the sporadic 10 December activity, this emission was of a continuous pulsing nature and surges rose at least 150 m above the summit. This was the most energetic activity observed during the last several months. For the next five hours Pavlof was visible but quiet.
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: P. Sventek, USAF, Cold Bay.