Cone A 1958/8

Start: August 14, 1958 [1]

Stop: September 2, 1958 ± 3 Days [1]

Event Type: Explosive

Max VEI: 3 [2]

Event Characteristics:

Description: From Grey (2003): "After a 13-year hiatus in reported eruptive activity, Okmok returned to life the evening of August 14, 1958. Eruptive activity was first reported by sheep ranchers on northeastern Umnak, and by Reeve Aleutian Airways personnel on the island (Anchorage Daily News/Times, August 15, 16, and 19, 1958). Reeve pilot Everett Skinner flew from Dutch Harbor to Nikolski on the SW end of Umnak Island on the morning of August 15 and observed an ash plume over Okmok reaching 5.5-6.0 km (Reeder, 1984). On his return flight from Nikolski, Skinner flew inside the caldera to photograph and observe the eruption [see figure 4.6 in original text]. The active vent was Cone A, where two ~35 m-high lava fountains at the NE base of the cone fed a basaltic a'a lava flow extending to the NNE, eventually reaching 7.8 km in length and covering 9.36 square km [see figure 4.7 in original text] (Reeder, 1984). According to James Bynum (Anchorage Daily News, August 29, 1958) the flow was still active on August 29, but when Skinner flew by Okmok again on September 5, he saw only steam rising from the cone and flow [see figure 4.6 in original text]. Thus, the effusion rate must have been relatively high in order for the flow to reach its full length in only two weeks. John Reeder estimated a mean thickness of 12.8 m and a volume of 1.2 x 10^8 cubic meters, which is 6-12 times larger than the estimated volume of the 1945 flows at 1-2 x 10^7 cubic meters (Reeder, 1984)."

Images

References Cited

[1] Okmok, 1984

Reeder, J. W., 1984, Okmok: Bulletin of Volcanic Eruptions, v. 22, p. 92-94.

[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.

[3] Post-caldera eruptions at Okmok volcano, Umnak Island, Alaska, with emphasis on recent eruptions from Cone A, 2003

Grey, D. M., 2003, Post-caldera eruptions at Okmok volcano, Umnak Island, Alaska, with emphasis on recent eruptions from Cone A: University of Alaska Fairbanks unpublished M.S. thesis, 135 p.

[4] Rivers of lava flowing from Alaska volcano, 1958

Wood, Hal, 1958, Rivers of lava flowing from Alaska volcano: Anchorage Daily News, v. Aug. 16, 1958, Anchorage, AK, p. unknown.

[5] Island peak erupting, 1958

Thomas, Lynn, 1958, Island peak erupting: Anchorage Daily News, v. Aug. 15, 1958, Anchorage, AK, p. unknown.

Complete Eruption References

Post-caldera eruptions at Okmok volcano, Umnak Island, Alaska, with emphasis on recent eruptions from Cone A, 2003

Grey, D. M., 2003, Post-caldera eruptions at Okmok volcano, Umnak Island, Alaska, with emphasis on recent eruptions from Cone A: University of Alaska Fairbanks unpublished M.S. thesis, 135 p.
Hard Copy held by AVO at FBKS - CEC file cabinet

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

Rivers of lava flowing from Alaska volcano, 1958

Wood, Hal, 1958, Rivers of lava flowing from Alaska volcano: Anchorage Daily News, v. Aug. 16, 1958, Anchorage, AK, p. unknown.
Hard Copy held by AVO at FBKS - CEC file cabinet

Umnak residents ask for volcano study, 1958

Unknown, 1958, Umnak residents ask for volcano study: Anchorage Daily News, v. Aug. 19, 1958, Anchorage, AK, p. unknown.
Hard Copy held by AVO at FBKS - CEC file cabinet

Island peak erupting, 1958

Thomas, Lynn, 1958, Island peak erupting: Anchorage Daily News, v. Aug. 15, 1958, Anchorage, AK, p. unknown.
Hard Copy held by AVO at FBKS - CEC file cabinet

Okmok, 1984

Reeder, J. W., 1984, Okmok: Bulletin of Volcanic Eruptions, v. 22, p. 92-94.