Report on Veniaminof (United States) — 30 October-5 November 2002
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 30 October-5 November 2002
Managing Editor: Gari Mayberry
Please cite this report as:
Global Volcanism Program, 2002. Report on Veniaminof (United States). In: Mayberry, G (ed.), Weekly Volcanic Activity Report, 30 October-5 November 2002. Smithsonian Institution and US Geological Survey.
56.17°N, 159.38°W; summit elev. 2507 m
All times are local (unless otherwise noted)
Veniaminof remained restless during 25 October to 1 November. Although the current seismic activity is lower than when first noted in early September, it is still above background level. AVO received video footage recorded in early October that showed minor ash emission from the intracaldera cone. The ash rose about 100-200 m above the cone and drifted a short distance before dispersing. A faint covering of ash was visible on the caldera ice field extending from the base of the cone. These observations are consistent with the elevated level of seismicity and are indicative of the type of minor activity that is occurring. Due to the continuing seismicity and reports of minor ash emissions the Concern Color Code at Veniaminof remained at Yellow.
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.