7 May, 1200: all flanks of volcano snow-covered. 14 May, 1500: dark ash visible on cone. 16 May, 2100: dark ash and steam emission visible. 20 May: upper 100 m of cone irregularly darkened, apparently from ash. Steam issuing from cone. At 2000, a thin layer of ash at the 3,000-m level was carried S for at least 25 km. At 2045, light grey material was ejected a few hundred meters. 21 May, 0900-0930: steaming. 31 May, 1200-1500: quiet. No longer possible to distinguish (at distance) between new ash darkening snow and dark bedrock exposed by melting snow.

Geological Summary. 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.