Report on Redoubt (United States) — 27 May-2 June 2009
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 27 May-2 June 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, 27 May-2 June 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 27 May-2 June seismicity from Redoubt remained low, but above background levels; small discrete earthquakes and rockfall signals in the summit region were recorded. Growth of the lava dome in the summit crater continued. Cloudy conditions obscured satellite and web camera views. AVO warned that the unstable lava dome could fail with little or no warning, leading to significant ash emissions and possible lahars in the Drift River valley. The Volcanic Alert Level remained at Watch and the Aviation Color Code remained at Orange.
Geologic Background. Redoubt is a 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 13,000-10,500 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 3,500 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 had severe economic impact on the Cook Inlet region and affected air traffic far beyond the volcano.