Report on Pavlof (United States) — 7 June-13 June 2017
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 7 June-13 June 2017
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2017. Report on Pavlof (United States). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 7 June-13 June 2017. Smithsonian Institution and US Geological Survey.
55.417°N, 161.894°W; summit elev. 2493 m
All times are local (unless otherwise noted)
On 7 June AVO reported that during the past several days an increase in low-frequency earthquake activity was detected at Pavlof. This kind of activity can sometime precede eruptive episodes. In addition, several short-duration tremor bursts were observed, and a pilot reported a possible ash cloud to 1.2 km (4,000 ft) a.s.l. Infrasound data from instruments on the volcano and from a more distant network in Sand Point showed no evidence of significant explosive activity. AVO noted that since activity prior to eruptions of Pavlof had always been very subtle, they increased the Aviation Color Code to Yellow and the Alert Level to Advisory based on these observations. During 8-9 June gas emissions from the summit were observed in web camera images and by local observers in Cold Bay (60 km SW). AVO noted that vapor emissions (with or without minor amounts of volcanic ash) are common and may occur from the summit vent at any time.
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.