Westdahl 1978/2
Start: February 4, 1978 [1]
Stop: February 9, 1978 [2]
Event Type: Explosive
Max VEI: 3 [3]
- Central eruption [2]
- Subglacial [3]
- Lahar, debris-flow, or mudflow [7]
- Cone [2]
- Steam [1]
Description: Around 1:15 pm on February 4, 1978, Clark (1978) observed "great billowing clouds of steam with a drifting black backdrop that suggested falling ash. * * * This was accompanied by lightning, thunder and the smell of sulphur. * * * By 4:00 pm the cloud had become much broader and dark * * * and Clark observed 'swaths of melting snow coming down the hillside.' By 4:30 pm the ash was thick at Scotch Cap. At 6:45 pm Clark 'experienced hail; small stones. The stones are dark. The ash has actually been seeding the clouds! We have noticed small bits of cinder from the cores of the hailstones.' At 7:35 pm a foot of ash had built up. At 11:35 pm lightning continued, and appeared red. Hail and cinder storms continued on and off at Scotch Cap, along with lightning and thunder, until the afternoon of February 5, when the cloud traveled to the southwest. Clark also reports, on February 6, that the road from Scotch Cap to Cape Serichef was washed out, leaving a 30 foot drop off, at least 100 yards across.
From Krafft and others (1980): The U.S. Coast Guard reported on 6 February that ash, accompanied by a sulfur odor, was falling on a station located at the foot of Westdahl. Lightning was observed above the summit, accompanied by thunder and rumbling. Reeve Aleutian Airways personnel report an ash cloud rising to 8,000 -10,000 m altitude, including some large blocks visible above the 3000 m cloud layer. Snow contaminated by dark ash fell on the freight vessel UNITED SPIRT between 12:00 and about midnight on 7 February, as it steamed from 48.8 degrees N, 152.5 degrees W to 49.2 degrees N, 156.3 degrees W, about 1000 km SE of Westdahl. A plume was visible in a satellite image taken at 1129 on 9 February. After the 9th, activity declined to steaming. The new crater formed by the February eruption is about 1.5 km in diameter and 0.5 km deep, located at about 1450 m elevation. Its upper portion cuts through glacial ice, which reaches a thickness of 200 m on the N rim. The bottom of the vertical-walled crater is filled with blocks, ash, ice, and talus. A lahar deposit, originating on the WSW flank of the new crater, extends down the glacier on Westdahl's flank to the sea, cutting the road from Cape Sarichef to Scotch Cap. The thickness of the upper portion of the deposit averages about 50 cm, increasing to 1-3 m near the lower end (Data from: SEAN Bulletin, vol. 3, n. 1, p. 7, n.2, p. 3-6, n. 9, p. 9-11)."
From Krafft and others (1980): The U.S. Coast Guard reported on 6 February that ash, accompanied by a sulfur odor, was falling on a station located at the foot of Westdahl. Lightning was observed above the summit, accompanied by thunder and rumbling. Reeve Aleutian Airways personnel report an ash cloud rising to 8,000 -10,000 m altitude, including some large blocks visible above the 3000 m cloud layer. Snow contaminated by dark ash fell on the freight vessel UNITED SPIRT between 12:00 and about midnight on 7 February, as it steamed from 48.8 degrees N, 152.5 degrees W to 49.2 degrees N, 156.3 degrees W, about 1000 km SE of Westdahl. A plume was visible in a satellite image taken at 1129 on 9 February. After the 9th, activity declined to steaming. The new crater formed by the February eruption is about 1.5 km in diameter and 0.5 km deep, located at about 1450 m elevation. Its upper portion cuts through glacial ice, which reaches a thickness of 200 m on the N rim. The bottom of the vertical-walled crater is filled with blocks, ash, ice, and talus. A lahar deposit, originating on the WSW flank of the new crater, extends down the glacier on Westdahl's flank to the sea, cutting the road from Cape Sarichef to Scotch Cap. The thickness of the upper portion of the deposit averages about 50 cm, increasing to 1-3 m near the lower end (Data from: SEAN Bulletin, vol. 3, n. 1, p. 7, n.2, p. 3-6, n. 9, p. 9-11)."
Impact: About a foot of ash fell at Scotch Cap and radio signals were garbled. The ash had to be cleaned off of the Scotch Cap light and a generator had to be repaired at the lighthouse. The road from Scotch Cap to Cape Sarichef was washed out and Scotch Cap was evacuated by helicopter on February 8th. [2] [1]
Other Impacts: Evacuation of Scotch Cap by helicopter on February 8th. About a foot of ashfall at Scotch Cap and radio signals were garbled. Ash had to be cleaned off of the Scotch Cap light. [1] [2]
Images
References Cited
[1] Scotch Cap diary, 1978
Clark, M., Villegas, Bob, Stanley, Mike, and Standridge, Ray, 1978, Scotch Cap diary: unpublished personal account, 8 p.
[2] Westdahl, 1978
Smithsonian Institution, 1978, Westdahl: Scientific Event Alert Network Bulletin v. 03, n. 02, p. 3-6.[3] Volcanoes of the world [2nd edition], 1994
Simkin, Tom, and Siebert, Lee, 1994, Volcanoes of the world [2nd edition]: Tucson, Arizona, Geoscience Press, 349 p.[4] Shishaldin, 1978
Smithsonian Institution, 1978, Shishaldin: Scientific Event Alert Network Bulletin v. 03, n. 02, unpaged.[5] Westdahl, 1978
Smithsonian Institution, 1978, Westdahl: Scientific Event Alert Network Bulletin v. 03, n. 01, unpaged.[6] Westdahl, 1978
Smithsonian Institution, 1978, Westdahl: Scientific Event Alert Network Bulletin v. 03, n. 05, unpaged.[7] Westdahl, 1978
Smithsonian Institution, 1978, Westdahl: Scientific Event Alert Network Bulletin v. 03, n. 09, p. 9-11.Complete Eruption References
Scotch Cap diary, 1978
Clark, M., Villegas, Bob, Stanley, Mike, and Standridge, Ray, 1978, Scotch Cap diary: unpublished personal account, 8 p.


Eruption of Westdahl peak, 1978
Harris, G. L., 1978, Eruption of Westdahl peak: Alaska magazine, v. May 1978, .
Hard Copy held by AVO at FBKS - CEC file cabinet
Westdahl, 1980
Krafft, M., Miller, T., and Kienle, J., 1980, Westdahl: in Annual report of the world volcanic eruptions in 1978, Bulletin of Volcanic Eruptions, v. 18, p. 65-66.
Hard Copy held by AVO at FBKS - CEC file cabinet
Westdahl, 1994
Reeder, J. W., and Doukas, M., 1994, Westdahl: in Annual report of the world volcanic eruptions in 1991, Bulletin of Volcanic Eruptions, v. 31, p. 83-86.
Hard Copy held by AVO at FBKS - CEC file cabinet
Shishaldin, 1978
Smithsonian Institution, 1978, Shishaldin: Scientific Event Alert Network Bulletin v. 03, n. 02, unpaged.
Westdahl, 1978
Smithsonian Institution, 1978, Westdahl: Scientific Event Alert Network Bulletin v. 03, n. 01, unpaged.
Westdahl, 1978
Smithsonian Institution, 1978, Westdahl: Scientific Event Alert Network Bulletin v. 03, n. 02, p. 3-6.
Hard Copy held by AVO at FBKS - CEC file cabinet
Westdahl, 1978
Smithsonian Institution, 1978, Westdahl: Scientific Event Alert Network Bulletin v. 03, n. 05, unpaged.
Westdahl, 1978
Smithsonian Institution, 1978, Westdahl: Scientific Event Alert Network Bulletin v. 03, n. 09, p. 9-11.
Hard Copy held by AVO at FBKS - CEC file cabinet
Volcanoes of the world [2nd edition], 1994
Simkin, Tom, and Siebert, Lee, 1994, Volcanoes of the world [2nd edition]: Tucson, Arizona, Geoscience Press, 349 p.
Hard Copy held by AVO at FBKS - CEC shelf
Petrology and geochemistry of Westdahl and Pogromni volcanoes, Unimak Island, Alaska, 1983
Neal, R. J., 1983, Petrology and geochemistry of Westdahl and Pogromni volcanoes, Unimak Island, Alaska: University of Alaska Fairbanks unpublished M.S. thesis draft unpaged.
Hard Copy held by AVO at FBKS - CEC file cabinet
Hard Copy held by AVO at FBKS - CEC shelf