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ALASKA VOLCANO OBSERVATORY WEEKLY UPDATE
U.S. Geological Survey
Friday, September 26, 2014, 1:01 PM AKDT (Friday, September 26, 2014, 21:01 UTC)
54°45'19" N 163°58'16" W,
Summit Elevation 9373 ft (2857 m)
Current Volcano Alert Level: WATCH
Current Aviation Color Code: ORANGE
Low-level eruptive activity likely continues. Elevated surface temperatures were observed at the summit crater in satellite images on six days over the past week. Sound waves were detected from the direction of Shishaldin on infrasound sensors in Dillingham at times during the week, consistent with low-level activity. Web camera views were mostly obscured by clouds and seismicity remained at a low level.
Shishaldin volcano, located near the center of Unimak Island in the eastern Aleutian Islands, is a spectacular symmetric cone with a base diameter of approximately 16 km (10 mi). A small summit crater typically emits a noticeable steam plume with occasional small amounts of ash. Shishaldin is one of the most active volcanoes in the Aleutian volcanic arc, with at least 54 episodes of unrest including over 24 confirmed eruptions since 1775. Most of Shishaldin's eruptions have produced small ash and steam plumes, although a recent eruption in April-May 1999 generated an ash column that reached a height of 45,000 ft above sea level.
52°49'20" N 169°56'42" W,
Summit Elevation 5676 ft (1730 m)
Current Volcano Alert Level: ADVISORY
Current Aviation Color Code: YELLOW
Elevated surface temperatures were observed at the summit on three days over the past week. Occasionally, minor steaming from the summit was visible in web camera images. No significant activity was noted in seismic or infrasound data.
New seismic and web camera data from Cleveland are now available for public viewing on our web site. Please see: https://www.avo.alaska.edu/activity/Cleveland.php
Cleveland volcano forms the western half of Chuginadak Island, a remote and uninhabited island in the east central Aleutians. The volcano is located about 75 km (45 mi) west of the community of Nikolski, and 1500 km (940 mi) southwest of Anchorage. The most recent significant period of eruption began in February, 2001 and produced 3 explosive events that generated ash clouds as high as 39,000 ft above sea level. The 2001 eruption also produced a lava flow and hot avalanche that reached the sea. Since then, Cleveland has been intermittently active producing small lava flows within its summit crater. These extrusive episodes are typically followed by explosions that destroy the lava flow, generate small ash clouds generally below 20,000 ft ASL, and launch debris onto the upper slopes of the volcanic cone.
OTHER ALASKA VOLCANOES
Other Alaska volcanoes show no signs of significant unrest: http://www.avo.alaska.edu/activity/
AVO scientists conduct daily checks of earthquake activity at all seismically-monitored volcanoes, examine web camera and satellite images for evidence of airborne ash and elevated surface temperatures, and consult other monitoring data as needed.
For definitions of Aviation Color Codes and Volcano Alert Levels, see: http://www.avo.alaska.edu/color_codes.php
FOR MORE INFORMATION ON ALASKA VOLCANOES: http://www.avo.alaska.edu
SUBSCRIBE TO VOLCANO ALERT MESSAGES by email: http://volcanoes.usgs.gov/vns/
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Chris Waythomas, Acting Scientist-in-Charge, USGS
firstname.lastname@example.org (907) 786-7497
Jeff Freymueller, Coordinating Scientist, UAFGI
email@example.com (907) 322-4085
The Alaska Volcano Observatory is a cooperative program of the U.S. Geological Survey, the University of Alaska Fairbanks Geophysical Institute, and the Alaska Division of Geological and Geophysical Surveys.