Pavlof 1981/9
Start: 10:00:00 September 25, 1981 [1]
Stop: 12:20:00 September 27, 1981 [1]
Event Type: Explosive
Max VEI: 3 [2]
- "Fire", "Glowing", or incandescence [1]
Description: From McNutt and Shackleford (1983): "About two weeks before this eruption, a seismometer 7.5 km SE of summit began to register occasional harmonic tremor, plus an increase in the size of B-type events. However, just a few days before the commencement off visible activity, there was a decrease in the number and size of earthquakes recorded. On 24 Sept. there were no visible signs of unrest at Pavlof.
"On 25 September, explosive eruption started possibly at 10:00 local time (= GMT - 9 hr.). An eruption plume was observed at 10:30. This plume drifted to the E & SE. During the day eruptive activity waxed. At 15:45 the plume had risen to 9 km a.s.l. Another major eruptive pulse commenced shortly before 19:45; by 22:15 the new plume top had reached 10.5 km a.s.l. The strongest activity of the eruption took place on the night of 25-26 Sept. A boat in Pavlof Bay received 4 cm of ash that night; the ash was medium coarse sand size. Observations from Pavlof Bay that night noted vividly incandescent, violent Strombolian activity with black ash clouds.
"On 26 September, another significant eruption began at ca. 07:00, plume height of 7.5 km a.s.l. noted at 09:30. Again, local observers reported billowing clouds of black ash and a brightly incandescent eruption column. By 10:00, the plume had decreased in height to 6 - 7 km a.s.l., and an active lava flow - brightly glowing - was seen on NNW flank, coming from a vent some 100 m below the summit crater. Waning activity in the afternoon. During the night of 26-27 Sept. ash fell on Squaw Harbor (Unga Island, 90 km ESE of Pavlof) to, perhaps, a depth of 1 cm. This ash was fine sand size.
"On 27 September, fine ash still fell at Squaw Harbor in the early morning hours. Ground reports indicate eruptions of black ash and glowing tephra also. Strong, continuous harmonic tremor ended at 12:20. However, seismicity (B-type earthquakes) of small magnitude (0-1) remained high for several months afterwards.
"This eruption is fairly typical of eruptions observed over the last 10 years at Pavlof."
McNutt, 1987 reports this eruption produced approximately 1.0-1.7x10^7 cubic meters of ash, and 4.7-5.8x10^6 cubic meters of lava as a rootless lava flow of basaltic-andesite composition."
"On 25 September, explosive eruption started possibly at 10:00 local time (= GMT - 9 hr.). An eruption plume was observed at 10:30. This plume drifted to the E & SE. During the day eruptive activity waxed. At 15:45 the plume had risen to 9 km a.s.l. Another major eruptive pulse commenced shortly before 19:45; by 22:15 the new plume top had reached 10.5 km a.s.l. The strongest activity of the eruption took place on the night of 25-26 Sept. A boat in Pavlof Bay received 4 cm of ash that night; the ash was medium coarse sand size. Observations from Pavlof Bay that night noted vividly incandescent, violent Strombolian activity with black ash clouds.
"On 26 September, another significant eruption began at ca. 07:00, plume height of 7.5 km a.s.l. noted at 09:30. Again, local observers reported billowing clouds of black ash and a brightly incandescent eruption column. By 10:00, the plume had decreased in height to 6 - 7 km a.s.l., and an active lava flow - brightly glowing - was seen on NNW flank, coming from a vent some 100 m below the summit crater. Waning activity in the afternoon. During the night of 26-27 Sept. ash fell on Squaw Harbor (Unga Island, 90 km ESE of Pavlof) to, perhaps, a depth of 1 cm. This ash was fine sand size.
"On 27 September, fine ash still fell at Squaw Harbor in the early morning hours. Ground reports indicate eruptions of black ash and glowing tephra also. Strong, continuous harmonic tremor ended at 12:20. However, seismicity (B-type earthquakes) of small magnitude (0-1) remained high for several months afterwards.
"This eruption is fairly typical of eruptions observed over the last 10 years at Pavlof."
McNutt, 1987 reports this eruption produced approximately 1.0-1.7x10^7 cubic meters of ash, and 4.7-5.8x10^6 cubic meters of lava as a rootless lava flow of basaltic-andesite composition."
References Cited
[1] Pavlof, 1983
McNutt, S., and Shackelford, D. C., 1983, Pavlof: in Annual report of the world volcanic eruptions in 1981, Bulletin of Volcanic Eruptions, v. 21, p. 60-61.[2] Volcanoes of the world [2nd edition], 1994
Simkin, Tom, and Siebert, Lee, 1994, Volcanoes of the world [2nd edition]: Tucson, Arizona, Geoscience Press, 349 p.[3] Pavlof, 1981
Smithsonian Institution, 1981, Pavlof: Scientific Event Alert Network Bulletin v. 06, n. 09, unpaged.[4] Shishaldin, 1981
Smithsonian Institution, 1981, Shishaldin: Scientific Event Alert Network Bulletin v. 06, n. 09, unpaged.Complete Eruption References
A seismotectonic analysis of the seismic and volcanic hazards in the Pribilof Islands - Eastern Aleutian Islands Region of the Bering Sea, 1983
Jacob, K. H., and Hauksson, Egill, 1983, A seismotectonic analysis of the seismic and volcanic hazards in the Pribilof Islands - Eastern Aleutian Islands Region of the Bering Sea: Lamont-Doherty Geological Observatory of Columbia University Annual Report NOAA 03--5-022-70, New York, 224 p.
The eruptive activity, seismicity, and velocity structure of Pavlof volcano, Eastern Aleutians, 1985
McNutt, S. R., 1985, The eruptive activity, seismicity, and velocity structure of Pavlof volcano, Eastern Aleutians: Columbia University unpublished Ph.D. dissertation, 214 p.
Hard Copy held by AVO at FBKS - CEC file cabinet
Hard Copy held by AVO at FBKS - CEC shelf
Eruption characteristics and cycles at Pavlof Volcano, Alaska, and their relation to regional earthquake activity (USA), 1987
McNutt, S. R., 1987, Eruption characteristics and cycles at Pavlof Volcano, Alaska, and their relation to regional earthquake activity (USA): Journal of Volcanology and Geothermal Research, v. 31, n. 3, p. 239-267.
Volcanoes of the world [2nd edition], 1994
Simkin, Tom, and Siebert, Lee, 1994, Volcanoes of the world [2nd edition]: Tucson, Arizona, Geoscience Press, 349 p.
Hard Copy held by AVO at FBKS - CEC shelf
Pavlof, 1983
McNutt, S., and Shackelford, D. C., 1983, Pavlof: in Annual report of the world volcanic eruptions in 1981, Bulletin of Volcanic Eruptions, v. 21, p. 60-61.
Hard Copy held by AVO at FBKS - CEC file cabinet
Pavlof, 1981
Smithsonian Institution, 1981, Pavlof: Scientific Event Alert Network Bulletin v. 06, n. 09, unpaged.
Shishaldin, 1981
Smithsonian Institution, 1981, Shishaldin: Scientific Event Alert Network Bulletin v. 06, n. 09, unpaged.