Report on Redoubt (United States) — 22 April-28 April 2009
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 22 April-28 April 2009
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2009. Report on Redoubt (United States). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 22 April-28 April 2009. Smithsonian Institution and US Geological Survey.
60.485°N, 152.742°W; summit elev. 3108 m
All times are local (unless otherwise noted)
AVO reported that during 22-28 April seismicity from Redoubt remained above background levels, indicating ongoing growth of the lava dome in the summit crater. On 22 April, the web camera showed steam-and-gas plumes that may have occasionally contained small amounts of ash rising from the lava dome. Views during 23-28 April were prevented by meteorological clouds. Pilots reported sulfur odors to the NE on 22 April and to the S on 28 April. The Volcanic Alert Level remained at Watch and the Aviation Color Code remained at Orange.
Geologic Background. Redoubt is a 3108-m-high glacier-covered stratovolcano with a breached summit crater in Lake Clark National Park about 170 km SW of Anchorage. Next to Mount Spurr, Redoubt has been the most active Holocene volcano in the upper Cook Inlet. The volcano was constructed beginning about 890,000 years ago over Mesozoic granitic rocks of the Alaska-Aleutian Range batholith. Collapse of the summit of Redoubt 10,500-13,000 years ago produced a major debris avalanche that reached Cook Inlet. Holocene activity has included the emplacement of a large debris avalanche and clay-rich lahars that dammed Lake Crescent on the south side and reached Cook Inlet about 3500 years ago. Eruptions during the past few centuries have affected only the Drift River drainage on the north. Historical eruptions have originated from a vent at the north end of the 1.8-km-wide breached summit crater. The 1989-90 eruption of Redoubt had severe economic impact on the Cook Inlet region and affected air traffic far beyond the volcano.