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Westdahl reported activity




Start:February 4, 1978 Observed
Stop:February 9, 1978 Observed

Tephrafall: BibCard BibCard BibCard BibCard BibCard
Lahar, debris-flow, or mudflow: BibCard
Cinder cone: BibCard
Steam: BibCard
Tephra plume: BibCard BibCard BibCard BibCard
Subglacial: BibCard
Central eruption: BibCard
Eruption Type:Explosive
MaxVEI: 3 BibCard
ColHeight: 10000 m BibCard
Duration: about 6 days BibCard
Eruption Product: basaltic andesite BibCard

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)."

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