Report on Pavlof (United States) — February 1976
Natural Science Event Bulletin, vol. 1, no. 5 (February 1976)
Managing Editor: David Squires.
Pavlof (United States) Ash eruptions and lava flows during 21-24 February
Please cite this report as:
Global Volcanism Program, 1976. Report on Pavlof (United States). In: Squires, D (ed.), Natural Science Event Bulletin, 1:5. Smithsonian Institution. http://dx.doi.org/10.5479/si.GVP.NSEB197602-312030.
55.417°N, 161.894°W; summit elev. 2493 m
All times are local (unless otherwise noted)
At approximately 1400 on 20 February, Pavlof was seen to eject ash clouds at about 3-minute intervals. The ash clouds moved S and dissipated into a layer near the 3,000 m level. After sunset, lava emissions became visible, but were not as energetic as those observed on 31 December.
At 2230 22 February, a USAF pilot flying at 12.5 km reported that lava was visible trailing as a rivulet down the entire NW flank. The volcano continuously emitted lava during the 45-minute pilot observation. On 23 February at 1530 a pilot reported that the activity was basically the same as on the 22nd. On 24 February at 1115 another pilot reported that the lava activity appeared to have ceased, but that strong winds were driving ash, smoke and steam down the S side of the volcano.
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.