Geological and Seismological Evidence of Increased Explosivity during the 1986 Eruptions of Pavlof Volcano, Alaska

Stephen R. McNutt, T. Miller, J. J. Taber

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Abstract

We present results of study of the best-documented eruptions of Pavlof volcano in historic time. The 1986 eruptions were mostly Strombolian in character; a strong initial phase may have been Vulcanian. The 1986 activity erupted at least 8×10 6 m 3 of feldspar-phyric basaltic andesite lava (SiO 2 =53–54%), and a comparable volume of wind-borne tephra. During the course of the eruption, 5300 explosion earthquakes occurred, the largest of which was equivalent to an M L =2.5 earthquake. Volcanic tremor was recorded for 2600 hours, and the strongest tremor was recorded out to a distance of 160 km and had an amplitude of at least 54 cm 2 reduced displacement. The 1986 eruptions modified the structure of the vent area for the first time in over two decades. A possible pyroclastic flow was observed on 19 June 1986, the first time such a phenomenon has been observed at the volcano. Overall, the 1986 eruptions were the strongest and longest duration eruptions in historic time, and changed a temporal pattern of activity that had persisted from 1973–1984.

Original languageAmerican English
JournalBulletin of Volcanology
Volume53
DOIs
StatePublished - Feb 1 1991
Externally publishedYes

Keywords

  • Initial Phase
  • Historic Time
  • Temporal Pattern
  • Tephra
  • Sedimentology

Disciplines

  • Earth Sciences

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