(2) Issued:20090106/(0028Z)
(3) Volcano:Shishaldin (CAVW# 1101-36-)
(4) Current Color Code:YELLOW
(5) Previous Color Code:GREEN
(6) Source:Alaska Volcano Observatory
(7) Notice Number:2009/A2
(8) Volcano Location:N 54 deg 45 min W 163 deg 58 min
(9) Area:Aleutians Alaska
(10) Summit Elevation:9373 ft (2857 m)
(11) Volcanic Activity Summary:AVO has detected a significant thermal anomaly and a slight increase in earthquake activity at Shishaldin Volcano on Unimak Island in the eastern Aleutians. Together, these observations indicate a departure from background conditions at Shishaldin. AVO is raising the Aviation Color Code to YELLOW and the Volcano Alert Level to ADVISORY. There is no indication that an eruption is imminent or certain, although the potential for an eruption has increased. AVO will continue to monitor the volcano closely.
(12) Volcanic cloud height:NIL
(13) Other volcanic cloud information:NIL
(14) Remarks: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 10 miles (16 km). 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, erupting atleast 28 times since 1775. Most of Shishaldin's eruptions have consisted of small ash and steam plumes, although the most recent eruption in April-May 1999 produced an ash column that reached a height of 45,000 ft above sea level.
(15) Contacts:Peter Cervelli, Acting Scientist-in-Charge, USGS pcervelli@usgs.gov (907) 786-7497 Jon Dehn, Acting Coordinating Scientist, UAFGI jdehn@gi.alaska.edu (907) 474-6499
(16) Next Notice:A new VONA will be issued if conditions change significantly or alert levels are modified. While a VONA is in effect, regularly scheduled updates are posted at http://www.avo.alaska.edu