Report on Veniaminof (United States) — 11 September-17 September 2002
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 11 September-17 September 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, 11 September-17 September 2002. Smithsonian Institution and US Geological Survey.
56.17°N, 159.38°W; summit elev. 2507 m
All times are local (unless otherwise noted)
On 10 September AVO detected 1-minute-long pulses of low-frequency tremor occurring every 2-5 minutes on several seismic stations at Veniaminof. This type of seismicity is indicative of volcanic unrest. Retrospective analysis of seismic data suggested that tremor began as early as 8 September. Through at least 16 September the overall level of seismicity decreased, but remained above background levels. Veniaminof was 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 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.