Report on Veniaminof (United States) — August 1983
Scientific Event Alert Network Bulletin, vol. 8, no. 8 (August 1983)
Managing Editor: Lindsay McClelland.
Veniaminof (United States) Lava flow and ash emission stop; tremor summarized
Please cite this report as:
Global Volcanism Program, 1983. Report on Veniaminof (United States). In: McClelland, L (ed.), Scientific Event Alert Network Bulletin, 8:8. Smithsonian Institution. http://dx.doi.org/10.5479/si.GVP.SEAN198308-312070.
56.17°N, 159.38°W; summit elev. 2507 m
All times are local (unless otherwise noted)
During an overflight on 26 July, the active cone emitted small bursts of pink-gray ash, and a white vapor cloud rose from the summit area. Bursts of steam rose from the lava flow which was forming a "delta" in the meltwater lake. Gray ash covered the entire caldera floor. Concentric fractures around the older cinder cone NE of the active cone were also observed.
The eruption appeared to be declining in late July-August. No ash emission was observed on 17 August at 1930, although a white vapor cloud rose above the active vent. The lava flow did not appear to be moving; no incandescence or steaming was observed on the flow. The water level was lower in the meltwater lake than during the 3 August overflight.
Geologic Background. Massive Veniaminof volcano, one of the highest and largest volcanoes on the Alaska Peninsula, is truncated by a steep-walled, 8 x 11 km, glacier-filled caldera that formed around 3700 years ago. The caldera rim is up to 520 m high on the north, is deeply notched on the west by Cone Glacier, and is covered by an ice sheet on the south. Post-caldera vents are located along a NW-SE zone bisecting the caldera that extends 55 km from near the Bering Sea coast, across the caldera, and down the Pacific flank. Historical eruptions probably all originated from the westernmost and most prominent of two intra-caldera cones, which rises about 300 m above the surrounding icefield. The other cone is larger, and has a summit crater or caldera that may reach 2.5 km in diameter, but is more subdued and barely rises above the glacier surface.
Information Contacts: M.E. Yount and T. Miller, USGS, Anchorage; S. McNutt, LDGO.