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Alaska Volcanoes Update
Friday, June 6, 1997, 11:00 AM ADT (1900 UTC)
Pavlof Volcano: 55o25' N, 161o54' W; summit elevation 2,518 m (8,262 feet)
LEVEL OF CONCERN COLOR CODE: YELLOW
The slight increase in the level of seismicity that began on Sunday,
June 2, continued through the week at Pavlof Volcano. On
Monday, National Weather Service observers at Cold Bay
reported seeing a steam plume 3,000 ft above the summit of the
volcano. On Tuesday, satellite images recorded a moderate
thermal anomaly at Pavlof. Since then, AVO has received no further
reports of unusual activity at Pavlof and clouds have obscured
the volcano for the remainder of the week. Based on the recent
eruptive activity at Pavlof (September - December, 1996),
renewed activity at this time could be expected. AVO has a seismic
network of six stations near the volcano; this network is monitored
by a computerized alarm system.
Pavlof Volcano, perhaps the most active volcano in the Aleutian volcanic arc,
has a history of 3-8 year-long periods of repose between eruptions. A new
eruption is then marked by a period of strong explosive events
that can send ash plumes to over 10 km (33,000 feet) above sea
level. The eruptive phase then changes to sporadic strombolian
eruption of lava spatter and small amounts of ash that may last
several months. Spatter-fed lava flows emanate from the summit
vent on occasion. The eruption then typically has a quiet period of
several months followed by renewed strombolian activity.
Pavlof was most recently active from September 13 to late December of 1996.
The nearest towns to the volcano are Cold Bay (37 mi), King Cove (30
mi), Sand Point (60 mi), and Nelson Lagoon (50 mi); these towns could expect light ash fall
depending on wind direction and continuing eruptive activity.
Mudflows and some flooding in the Cathedral River valley north of
the volcano may occur. Airborne ash hazards to aircraft may be
considerable if a large explosive event occurs but are much less
severe during a typical Strombolian phase.
Shishaldin Volcano: 54o45'N, 163o58'W; summit elevation 2857 m (9,373 ft)
On Monday, June 2, NWS observers in Cold Bay reported a possible
small steam and ash plume rising 1000 - 1500 ft above the summit
of Shishaldin and drifting about 5 miles downwind to the north. This
volcano is not seismically monitored but has frequent small
eruptions. AVO has received no additional reports of activity at
Shishaldin this week.