HR: 12:05h
AN: V52B-08    [Abstracts]
TI: The 2007 Eruption of Pavlof Volcano, Alaska
AU: * McNutt, S R
EM: steve@giseis.alaska.edu
AF: Alaska Volcano Observatory, Geophysical Inst., Univ. of Alaska Fairbanks, 903 Koyukuk Drive P.O. Box 757320, Fairbanks, AK 99775, United States
AB: Pavlof Volcano on the Alaska Peninsula began to erupt on August 15, 2007 after a 10.7 year repose. Precursor signals consisted of low-frequency earthquakes that began on August 14 and thermal anomalies that were likely coincident with the beginning of the eruption. The mainly strombolian eruptions are occurring from a new vent high on the SE flank of the volcano, separate from the NNE vent that had been active over the last several decades. Seismic activity, monitored by a network of 6 local instruments, consists of low-frequency events, explosion earthquakes, volcanic tremor, and lahar-generated signals. One station, PVV, is located only 220 m from a lahar channel, and lahars generate an easily distinguished high-frequency seismic signal. A commonly observed sequence is an increase in eruptive activity at the vent, accompanied by stronger tremor visible on all stations, and followed 12-30 minutes later by a lahar at PVV. This suggests that the eruption pulse ejects fresh hot material, which melts additional ice and snow to form new lahars. Steam and ash plumes have generally been below 15,000 ft, but rose as high as 20,000 ft on August 29 and 30. AVHRR remote sensing data showed an ash signal on these days, consistent with pilot reports. On August 30 lightning was observed in the plume from Cold Bay, 59 km SW. In response to the eruptions, AVO has been conducting 24 hr per day surveillance. Fieldwork to date has fortified seismic stations, and installed a new webcam, pressure sensor, and electric field meter. Collaborating scientists from the University of Alaska Fairbanks have installed aerosol sampling equipment at four locations, and collaborating scientists from New Mexico Tech have installed lightning detection equipment at four stations surrounding the volcano. Based on recent eruptions of Pavlof in 1981, 1986, 1996, etc., the eruptive activity is likely to last several months and may include one or more episodes of ash columns to heights of 30,000 ft or more. Additional field work is being planned as of this writing. The Alaska Volcano Observatory (AVO) is a cooperative program of the US Geological Survey, the University of Alaska Fairbanks (UAF), and the Alaska Division of Geological and Geophysical Surveys.
DE: 8414 Eruption mechanisms and flow emplacement
DE: 8419 Volcano monitoring (7280)
DE: 8425 Effusive volcanism
DE: 8494 Instruments and techniques
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2007 Fall Meeting