Report on Veniaminof (United States) — 24 July-30 July 2013
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 24 July-30 July 2013
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2013. Report on Veniaminof (United States). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 24 July-30 July 2013. Smithsonian Institution and US Geological Survey.
56.17°N, 159.38°W; summit elev. 2507 m
All times are local (unless otherwise noted)
AVO reported that the ongoing low-level eruption of Veniaminof, characterized by lava effusion and emissions of minor amounts of ash and steam, continued during 24-30 July, indicated by fluctuating volcanic tremor and occasional small explosions detected by the seismic network. On most days satellite images showed elevated surface temperatures at the cinder cone inside the caldera consistent with lava effusion. On 25 July a pilot reported an ash plume that rose 60-100 m above the cone and drifted almost 25 km S, and a "river of lava" flowing down from the cone. On 27 July a pilot observed an ash emission that rose 300-600 m and drifted NW. A water-rich plume likely containing minor amounts of ash was detected in satellite images drifting NW at an altitude of 4.5 km (15,000 ft) a.s.l. on 29 July. The Volcano Alert Level remained at Watch and the Aviation Color code remained at Orange.
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.