Report on Redoubt (United States) — June 1990
Bulletin of the Global Volcanism Network, vol. 15, no. 6 (June 1990)
Managing Editor: Lindsay McClelland.
Redoubt (United States) Continued shallow seismicity but little dome growth and declining SO2 emission
Please cite this report as:
Global Volcanism Program, 1990. Report on Redoubt (United States) (McClelland, L., ed.). Bulletin of the Global Volcanism Network, 15:6. Smithsonian Institution. https://doi.org/10.5479/si.GVP.BGVN199006-313030.
60.485°N, 152.742°W; summit elev. 3108 m
All times are local (unless otherwise noted)
This report covers the period 15 June-13 July 1990. "Shallow seismic activity at Redoubt has remained at low levels during the report period (figure 14). However, 3 larger-than-normal earthquakes occurred beneath Redoubt during late June, ranging in depth from 5.8 to 7.5 km and in magnitude from ML 1.6 to 1.8. The events pushed the seismic energy release at these depths to the highest levels seen since early March.
|Figure 14. Epicenter map top and depth vs. time plot bottom of earthquakes recorded near Redoubt by AVO, 15 June-13 July, 1990. Squares on the epicenter map mark the positions of seismic stations.|
"The lava dome and crater area have been largely obscured by clouds and heavy steaming during much of the report period. However, the dome was seen on several clear days in late June and early July, and observers saw no significant change in either its size or surface. Three COSPEC flights during the report period yielded SO2 emission rates of <1,000 t/d. These are the lowest values since COSPEC measurements began in late March."
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.
Information Contacts: AVO Staff.