Report on Veniaminof (United States) — 16 October-22 October 2002
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 16 October-22 October 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, 16 October-22 October 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 11-18 October. Although seismicity was lower than when first noted in early September, it was still above background levels. No new visual observations had been received since the last update. However, local observations of low-level activity earlier in the month confirm that small explosions at the intracaldera cone are possible at any time and may not correspond with a noticeably elevated level of seismicity. No thermal anomalies were observed on satellite imagery. AVO considered the activity at Veniaminof to be minor, but the exact nature of the unrest was unknown. Veniaminof remained at Concern Color Code 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.