AVO reported that during 4-10 March seismic activity at Redoubt was variable but remained above background levels. Clear web camera views and satellite imagery on 7 and 8 March showed no unusual activity. On 10 March, AVO reported that although abnormally high gas emission rates continued to be detected and melting of the summit glacier was still evident, the new magma beneath the volcano did not show any signs of upward movement. The Aviation Color Code was lowered to Yellow and the Alert Level was lowered to Advisory.

Geological Summary. 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.

Source: US Geological Survey Alaska Volcano Observatory (AVO)