AVO/USGS Volcanic Activity Notice Volcano: Okmok (CAVW #1101-29-) Current Volcano Alert Level: WARNING Current Aviation Color Code: RED Issued: Sunday, July 13, 2008, 8:24 AM AKDT (20080713/1624Z) Source: Alaska Volcano Observatory Notice Number: 2008/A9 Location: N 53 deg 23 min W 168 deg 9 min Elevation: 3520 ft (1073 m) Area: Aleutians Alaska Volcanic Activity Summary: The eruption at Okmok continues based on high levels of seismicity and ash continues to be erupted as indicated in satellite observations. Seismicity reached a peak at about 2200 Z (2:00 PM ADT) yesterday and has been gradually declining since. Reports from Unalaska indicate no ash fall in Unalaska/Dutch Harbor since last night. However, as of 0730 ADT the ash fall advisory for Nikolski and Unalaska/Dutch Harbor remains in effect. Recent Observations: [Volcanic cloud height] National Weather Service reports plume height to be up to 45,000 ft. above sea level. [Ash fall] Reports from Unalaska indicate no ash fall in Unalaska/Dutch Harbor since last night. However, as of 0730 ADT the ash fall advisory for Nikolski and Unalaska/Dutch Harbor remains in effect. Hazard Analysis: [General hazards] Ash fall is expected to continue downwind of the volcano including over marine areas in the North Pacific. Areas in the immediate vicinity of the volcano on Umnak Island should be avoided, particularly the Crater Creek drainage northeast of the caldera. [Ash cloud] An ash cloud is drifting southeast and east of the volcano and poses a risk to aircraft in the vicinity. The estimated cloud height for the ash cloud is up to 45,000 ft above sea level. [Ballistics] Ballistics may impact the areas around the caldera rim. [Lava flow/dome] Historical eruptions of Okmok have typically produced lava flows, however at this time we cannot confirm that a lava flow has been produced. Remarks: Okmok Volcano is located on the northeast end of Umnak Island in the eastern Aleutians about 65 miles southwest of Unalaska/Dutch Harbor. The volcano consists of a 6-mile-wide circular caldera or crater about 1600 feet deep that formed about 2000 years ago. Okmok has been frequently active in historical times producing ash clouds often accompanied by lava flows within the caldera. The most recent eruption occurred in 1997 and produced ash clouds and a lava flow that traveled about 5 miles across the caldera floor. Please see http://www.avo.alaska.edu/activity/Okmok.php for more information. Contacts: John Power, Acting Scientist-in-Charge, USGS jpower@xxxxxxxx (907) 786-7497 Steve McNutt, Coordinating Scientist, UAF steve@xxxxxxxxxxxxxxxxx (907) 474-7131 Next Notice: More information will be released as it is received. A new VAN will be issued if conditions change significantly or alert levels are modified. While a VAN is in effect, regularly scheduled updates are posted at http://www.avo.alaska.edu 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. ============================================================== To unsubscribe from the volcano list, send the message: signoff volcano to: listserv@xxxxxxx, or write to: volcano-request@xxxxxxxx To contribute to the volcano list, send your message to: volcano@xxxxxxxx Please do not send attachments. ==============================================================
