Report on Veniaminof (United States) — 31 December-6 January 2003
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 31 December-6 January 2003
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, 31 December-6 January 2003. Smithsonian Institution and US Geological Survey.
56.17°N, 159.38°W; summit elev. 2507 m
All times are local (unless otherwise noted)
Periods of nearly constant seismicity at Veniaminof since 31 December led AVO to raise the Concern Color Code from Green to Yellow on 6 January. Seismicity had been increasing since mid-December. No thermal anomalies were detected on satellite imagery. AVO stated that there were no indications of an imminent eruption, although low-level steaming and minor ash emission may occur.
Geologic Background. Veniaminof, on the Alaska Peninsula, is truncated by a steep-walled, 8 x 11 km, glacier-filled caldera that formed around 3,700 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.