Printer friendly versionALASKA VOLCANO OBSERVATORY WEEKLY UPDATEFriday, October 31, 2014 12:29 PM AKDT (Friday, October 31, 2014 20:29 UTC)SHISHALDIN VOLCANO
54°45'19" N 163°58'16" W, Summit Elevation 9373 ft (2857 m)
Current Volcano Alert Level: WATCH
Current Aviation Color Code: ORANGE
The low-level eruptive activity at Shishaldin Volcano increased over the past week and continues. Strong periods of tremor began to be recorded on October 25 along with elevated surface temperatures at the summit. The activity was also recorded on regional infrasound arrays. During clear webcam views, deposits of dark ash and ballistics were visible covering the summit. A steam and gas plume was observed in a satellite image on October 25, but there have been no observations or reports of ash clouds. Tremor continues, and the overall seismicity remains elevated. Over the past 24 hours nothing unusual was observed in cloudy satellite and webcamera images.
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 200-m-wide (660 ft) funnel-shaped summit crater typically emits a steam plume and 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 eruptions are relatively small, although the April-May 1999 event generated an ash column that reached 45,000 ft above sea level.CLEVELAND VOLCANO
52°49'20" N 169°56'42" W, Summit Elevation 5676 ft (1730 m)
Current Volcano Alert Level: ADVISORY
Current Aviation Color Code: YELLOW
No activity was observed in mostly cloudy satellite and webcam images in the past week. Seismicity remains at low levels.
Cleveland volcano forms the western portion 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, often followed by explosions that generate small ash clouds generally below 20,000 ft above sea level. These explosions also launch debris onto the slopes of the cone producing hot pyroclastic avalanches and lahars that sometimes reach the coastline. 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
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John Power, Scientist-in-Charge, USGS
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Jeff Freymueller, Coordinating Scientist, UAFGI
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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.