Akutan Volcano, Aleutian Islands, Alaska

Update 009

Alaska Volcano Observatory Update
Wednesday, March 20, 1996 5:00 pm AST (0200 UTC)

Level Of Concern Color Code: YELLOW

Color Code Is Being Downgraded From Previous Level ORANGE

The Level of Concern Color Code for Akutan volcano is being downgraded to YELLOW based on decreasing seismicity over the past 6 days. Several seismic stations have been emplaced near the volcano and data are being transmitted in real-time to AVO where analysis and interpretation is done on a 24-hr basis. The number of earthquakes recorded at the city of Akutan was over 800 per day during the intense swarm of March 13-14 when the ORANGE Color Code was designated. It has since decreased to 60-80 per day. The intense earthquake swarms of March 10-11 and 13-14 were likely caused by rapid intrusion of magma at depth beneath the volcano. An airline passenger reported seeing the snow-filled summit crater, with very slight normal wisp of steam from the central cinder cone, and no evidence of any eruptive activity. The level of seismicity remains above background, however, and several earthquakes each day are large enough to be felt in the city of Akutan. Thus, the volcano is still considered to be in a restless state. By going to YELLOW, AVO indicates that the threat of imminent eruption has declined, and the possibility that the volcano will return to quiet over a period of weeks without eruption has increased.

The following scenarios are considered possible:

  1. Earthquake activity diminishes and no eruption occurs
  2. Eruption of a lava flow from a vent on the flank or within the summit caldera, accompanied by ash plumes and explosions
  3. Explosive eruption producing ash plumes.

AVO is closely monitoring the situation. Further updates will be issued as information becomes available. Recordings of current information are available by calling 907-786-7478. Additionally, information on the Akutan situation is available on the Internet at: http://www.avo.alaska.edu/


Terry E.C. Keith                                        John Eichelberger
AVO Scientist-in-Charge                         AVO Coordinating Scientist
U.S. Geological Survey                                  Geophysical Institute
4200 University Drive                                   University of Alaska
Anchorage, AK  99508-4667                               Fairbanks, AK  99775
OFF= (907) 786-7443                                     OFF=(907) 474-5530