Westdahl 1795

Start: 1795 [1]

Event Type: Explosive

Max VEI: 4 [2]

Event Characteristics:
  • Lahar, debris-flow, or mudflow [1]
  • Tephra plume [1]

Description: From Miller and others (1998): "Veniaminov (1840, p. 18) described an eruption in 1795 on the southwest end of Unimak Island, which most likely occurred at Westdahl. Coats (1950) attributed four eruptions in the late eighteenth century and early nineteenth century to Pogromni volcano. Based on recent observations from aircraft, however, Pogromni does not appear to have been active in historical time. The eruptions should probably be assigned to Westdahl."
From Veniaminov (1840, translated by Lydia T. Black and R.H. Geoghegan, 1984): "In regard to volcanic phenomena, Unimak Island has occupied the first place since antiquity, both for its extraordinary size or the height and position of the mountains located on it. About 1795, with the wind from the SW, the range on the SW end of Unimak blew up with a terrible thunder and an eruption of ash [pepel] or soot [sazha], white in color, in such a great quantity that, for several hours in the middle of the day, not only in the neighboring villages on Aliaksa but even on Unga, there was absolute darkness. The eternal ice, lying on that range, slid down along both sides together with a large quantity of water and burned rocks of different sizes. The last stopped about half-way along and formed a trench or a black belt visible even now. There are still signs in places where the water flows and where the ice, which had slid down the mountain, rested for several years (the vegetation has only just begun to appear there). Nowadays one notices that this very range, which had been at rest after the upheaval, in the last few years, in one place, began to grow or bulge out."
Additionally, Plummer (1898) reports that the southwest crater exploded and fell in.
Sapper (1927) assigns this eruption to his category b1, and estimates more than 1 cubic km (10^9 cubic m) of tephra was erupted.

References Cited

[1] Notes on the islands of the Unalaska district [translated from Russian by Lydia T. Black and R.H. Geoghegan in 1984], 1840

Veniaminov, Ivan, 1840, Notes on the islands of the Unalaska district [translated from Russian by Lydia T. Black and R.H. Geoghegan in 1984]: Pierce, R. A., (ed.), Kingston, Ontario, Limestone Press, 511 p.

[2] 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.

Complete Eruption References

Catalog of the historically active volcanoes of Alaska, 1998

Miller, T. P., McGimsey, R. G., Richter, D. H., Riehle, J. R., Nye, C. J., Yount, M. E., and Dumoulin, J. A., 1998, Catalog of the historically active volcanoes of Alaska: U.S. Geological Survey Open-File Report 98-0582, 104 p.
title page PDF 52
intro and TOC PDF 268 KB
eastern part - Wrangell to Ukinrek Maars PDF 972 KB
central part - Chiginagak to Cleveland PDF 2,463 KB
western part - Carlisle to Kiska PDF 956 KB
references PDF 43 KB
Hard Copy held by AVO at FBKS - CEC shelf

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

Vulkankunde, 1927

Sapper, Karl, 1927, Vulkankunde: Stuttgart, Germany, Englehorn Verlag, 424 p.

Reported volcanic eruptions in Alaska, Puget Sound, etc., 1690-1896, 1898

Plummer, F. G., 1898, Reported volcanic eruptions in Alaska, Puget Sound, etc., 1690-1896: in Holden, E. S., (ed.), A Catalogue of Earthquakes on the Pacific Coast 1769-1897, Smithsonian Institution Miscellaneous Collections 1087, City of Washington D.C., Smithsonian Institution, p. 24-27.
Hard Copy held by AVO at FBKS - CEC file cabinet

Grewingk's geology of Alaska and the Northwest Coast of America [edited by Marvin W. Falk, translation by Fritz Jaensch published 2003], 1850

Grewingk, Constantine, 1850, Grewingk's geology of Alaska and the Northwest Coast of America [edited by Marvin W. Falk, translation by Fritz Jaensch published 2003]: Rasmuson Library Historical Translation Series 11, Fairbanks, AK, The University of Alaska Press, 242 p.
Hard Copy held by AVO at FBKS - CEC shelf

Notes on the islands of the Unalaska district [translated from Russian by Lydia T. Black and R.H. Geoghegan in 1984], 1840

Veniaminov, Ivan, 1840, Notes on the islands of the Unalaska district [translated from Russian by Lydia T. Black and R.H. Geoghegan in 1984]: Pierce, R. A., (ed.), Kingston, Ontario, Limestone Press, 511 p.
Hard Copy held by AVO at FBKS - CEC file cabinet
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