Report on Veniaminof (United States) — 22 January-28 January 2003
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 22 January-28 January 2003
Managing Editor: Gari Mayberry
Please cite this report as:
Global Volcanism Program, 2003. Report on Veniaminof (United States). In: Mayberry, G (ed.), Weekly Volcanic Activity Report, 22 January-28 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)
The elevated seismicity that began in mid-December 2002 at Veniaminof continued during 17-24 January. As during the previous week, periods of nearly constant seismicity were recorded during the report week. Discrete seismic events occurred at rates up to 1-2 events per minute, along with moderate levels of volcanic tremor. Satellite imagery did not reveal increased surface temperatures, ash emission, or ash deposits. Visual observations on 22 January from the village of Perryville, located 35 km SSW of the volcano, revealed that white steam was rising from the intracaldera cone. The steaming was similar to that observed over the previous several months. The Concern Color Code 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.