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Okmok reported activity





Event Name : Cone A 1981/3

Start:March 24, 1981 ± 6 HoursObserved
Stop:March 24, 1981 Observed

Tephrafall: BibCard
Steam: BibCard
Tephra plume: BibCard
Central eruption: BibCard BibCard
Eruption Type:Explosive
Duration: At least 1 hour BibCard
MaxVEI: 3 BibCard
ColHeight: 5500 m BibCard

Description: From Reeder (1987): "During the morning of 24 March 1981, pilot Harald Wilson observed a growing ash and steam eruption plume over Okmok Volcano. Harold was flying his Peninsula Airways, Inc. Navaho from Cold Bay to Dutch Harbor of Unalaska Island. His initial observation of the eruption plume was about 1000 local time (=GMT -10 h.) when he was about 80 km NNW of Dutch Harbor at a 2,600 m altitude. The plume of mixed steam and ash had reached an approximate 2,800 m altitude and was still growing. The visibility was good with a light wind from the ESE and with fairly cloudless sky. Before landing at Dutch Harbor 20 minutes later, Harold was able to watch the eruption plume grow to about a 5,500 m altitude, which was drifting to the NW.

"At 1100 on 24 March, Harold left Dutch Harbor for Nikolski of Umnak Island. During this flight, Harold flew over Okmok Caldera and circled the cinder cone that had just erupted (Cone A in the SW part of Okmok Caldera, see U.S. Geological Survey Bulletin 1028-L). The eruption had stopped and only steam was rising out of the cinder cone. Some ash was still in the air, but most of the plume had dissipated. A thin but very noticeable layer of black ash was deposited from the eruption on snow to the NW and WNW of the Cone A over the caldera floor as well as beyond.

"At 1500 of 24 March, Harold returned to Dutch Harbor from Nikolski. Only a small steam plume was being emitted from Cone A. Harold continued to fly to Nikolski about two to four times a week for Peninsula Airways, Inc. until late 1983. During these trips, Harold has only observed nearly continuous steam emission from Cone A, which is normal activity for this cone."

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