Akutan Volcano, Aleutian Islands, Alaska

Update 004

Alaska Volcano Observatory Update
Thursday, March 14, 1996 2:00 pm AST (2300 UTC)

Level Of Concern Color Code: ORANGE

Significant seismicity continues near Akutan volcano. AVO is initiating use of a Level of Concern Color Code (attached). We designate the current Level of Concern Color to be ORANGE indicating an eruption is possible at any time within the next few days. Based on the frequency, number and locations of recorded earthquakes, the following scenarios are considered possible at this time:

  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. Significant, explosive eruption producing ash plumes to altitudes of 30,000' ASL or higher.

Installation of additional seismometers may allow us to revise these scenarios in the days ahead.

Following intense felt seismicity reported by Akutan residents Sunday evening through Monday, an AVO seismologist arrived on Tuesday and installed a single seismometer to record earthquake activity. Seismicity declined Tuesday but Wednesday, at about 5:00 pm AST, felt-earthquakes began occurring at a rate of greater than 1 per minute, a higher rate than that on Monday, March 11. This activity continued through most of the night and many events were strongly felt in Akutan. Damage associated with these earthquakes included objects tumbling off shelves. The strongest of these events were felt as far away as Dutch Harbor/Unalaska 50 km to the southwest of Akutan. A slight decrease in the rate of activity occurred at about 5:00 am AST today, however felt earthquakes continue at a rate of about one every 2-3 minutes.

AVO is sending additional personnel and equipment to the area today. Since this seismic crisis began on Sunday evening, March 10, poor weather has prevented any visual observations of the volcano.

Akutan volcano is located on west central Akutan Island in the eastern Aleutian Islands 185 km southwest of the tip of the Alaska Peninsula and 1225 km southwest of Anchorage. The communities of Unalaska and Dutch Harbor, lie 50 km to the southwest. The city of Akutan (seasonal population of 750) lies 13.5 km east of the volcano. Akutan is a stratovolcano with a 2-km-wide summit crater with an active cinder cone. It is one of the most active volcanoes in the Aleutian arc with at least 27 separate eruptive episodes documented since 1790. The volcano frequently produces low-level eruptive activity including steam and ash emission. The most recent eruptive activity--localized steam and ash emission--occurred in 1992.

AVO is closely monitoring the situation. Further updates will be issued as information becomes available. Information on the Akutan situation may be accessed on the Internet at: http://www.avo.alaska.edu/


Terry E.C. Keith                         Chris Nye
AVO Scientist-in-Charge                  (Acting) 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) 474-7430
FAX= (907) 786-7425                      FAX=(907) 474-5618