Report on Veniaminof (United States) — 7 September-13 September 2005
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 7 September-13 September 2005
Managing Editor: Gari Mayberry
Please cite this report as:
Global Volcanism Program, 2005. Report on Veniaminof (United States). In: Mayberry, G (ed.), Weekly Volcanic Activity Report, 7 September-13 September 2005. Smithsonian Institution and US Geological Survey.
56.17°N, 159.38°W; summit elev. 2507 m
All times are local (unless otherwise noted)
On 7 September, AVO raised the Concern Color Code at Veniaminof from Green to Yellow after several minor bursts of ash occurred at the volcano during the afternoon. Ash bursts continued to occur through at least 9 September, with ash rising less than 3 km (10,000 ft) a.s.l. The ash was confined to the caldera. AVO reported that there were no indications that more vigorous activity was imminent or even likely. They expected that steam-and-ash emissions similar to those observed on 7 September might continue intermittently and could pose a hazard to people and low-flying aircraft in the vicinity of the active cone.
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 reaches an elevation of 2156 m and 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.