• Official Name: Mount Spurr
  • Seismically Monitored: Yes
  • Color Code: UNASSIGNED
  • Alert Level: UNASSIGNED
  • Elevation: 3374m (11069ft)
  • Latitude: 61.2989
  • Longitude: -152.2539
  • Smithsonian VNum: 313040
  • Nearby Towns:
    • Beluga 37 mi (60 km) SE
    • Tyonek 40 mi (65 km) SE
    • Nikiski 51 mi (81 km) SE
    • Susitna 55 mi (89 km) NE
    • Salamatof 56 mi (90 km) SE
  • Subfeatures:
    • Crater Peak


From Miller and others (1998) [1] : "Mount Spurr is a Quaternary stratovolcano located near the northeastern end of the Aleutian volcanic arc. It is the easternmost historically active volcano in the Aleutian arc and is the highest of several snow- and ice-covered peaks that appear to define a large, dissected stratovolcano [2] .
"Capps (1929) [3] suggested that a summit caldera, largely buried by ice, is associated with Mount Spurr. Later, Juhle and Coulter (1955) [2] disagreed with the caldera interpretation suggesting that the peaks around Mount Spurr only coincidentally resemble the rim of a large subsidence structure. Most recent studies, however, suggest that ancestral Mt. Spurr, constructed during late Pleistocene time [4] , was partially destroyed by a major Bezymianny-type eruption possibly as late as early Holocene time [5] [6] . The eruption produced a voluminous volcanic debris avalanche and subsequent pyroclastic flows that resulted in the formation of a 5- to 6-km-diameter explosion caldera. The volcanic debris avalanche contains blocks as much as 100 m in diameter and traveled a minimum of 25 km. The overlying pyroclastic flows are partially welded and are composed chiefly of high silica andesite. Present Mt. Spurr is the highest of several post-caldera, centrally located, ice-carved cones or domes.
"The youngest volcanic feature at Mount Spurr is a satellitic cone, Crater Peak, located in the breach in the caldera about 3.2 km south of Mount Spurr. Crater Peak has a summit crater that is itself slightly breached along the south rim; the north wall of the crater exposes the truncated remains of an older dome or lava lake. Crater Peak has been the source of all Late Holocene eruptive activity at Mt. Spurr [5] . Before the 1992 eruption, a small crater lake occupied the bottom of the crater."

Name Origin

A.H. Brooks named Mount Spurr in 1900, for Josiah Edward Spurr, a U.S. Geological Survey geologist who led an expedition in the area in 1898 (Orth, 1971).

References Cited

[1] Catalog of the historically active volcanoes of Alaska, 1998

Miller, T. P., McGimsey, R. G., Richter, D. H., Riehle, J. R., Nye, C. J., Yount, M. E., and Dumoulin, J. A., 1998, Catalog of the historically active volcanoes of Alaska: U.S. Geological Survey Open-File Report 98-0582, 104 p.

[2] The Mt. Spurr eruption, July 9, 1953, 1955

Juhle, R. W., and Coulter, H. W., 1955, The Mt. Spurr eruption, July 9, 1953: Eos, v. 36, n. 2, p. 199-202.

[3] The Mount Spurr region, Alaska, 1929

Capps, S. R., 1929, The Mount Spurr region, Alaska: U.S. Geological Survey Bulletin 0810-C, p. 141-172, 2 plates, scale 1:250,000.
full-text PDF 1.6 MB
plate 3 PDF 324 KB

[4] Geochronology of eruptive events at Mt. Spurr, Alaska, 1986

Turner, D. L., and Nye, C. J., 1986, Geochronology of eruptive events at Mt. Spurr, Alaska: in Turner, D. L. and Wescott, E. M., (eds.), Geothermal energy resource investigations at Mt. Spurr, Alaska, University of Alaska Fairbanks Geophysical Institute Report UAG-R 308, p. 20-27, 1 plate, scale 1:2,860.

[5] A reconnaissance of the major Holocene tephra deposits in the upper Cook Inlet region, Alaska, 1985

Riehle, J. R., 1985, A reconnaissance of the major Holocene tephra deposits in the upper Cook Inlet region, Alaska: Journal of Volcanology and Geothermal Research, v. 26, n. 1-2, p. 37-74.

[6] Petrology, geochemistry, and age of the Spurr volcanic complex, eastern Aleutian arc, 1990

Nye, C. J., and Turner, D. L., 1990, Petrology, geochemistry, and age of the Spurr volcanic complex, eastern Aleutian arc: Bulletin of Volcanology, v. 52, n. 3, p. 205-226.

Current Activity

February 16, 2024, 11:44 am

Due to severe winter weather conditions, AVO is unable to receive quality data from earthquake and other monitoring stations at Mount Spurr volcano 120 km (75 miles) west of Anchorage. Data are insufficient to establish the state of the volcano. As a result, the Aviation Color Code and Volcano Alert Level are changed to UNASSIGNED/UNASSIGNED. 



  • Heavy snowpack is preventing data from seismic stations at Mount Spurr volcano from reaching AVO in Anchorage.  

  • As a result, AVO can no longer track volcanic activity in real-time to provide early warning of eruptive activity. 

  • AVO plans to visit to a key repeater to assess damage and implement repairs during the next suitable weather window. 


Cause of network failure  

The high-altitude environment at Cook Inlet volcanoes often degrades network performance through the winter, but this season’s significant snowfall is having an outsized impact. Heavy snow and ice loads on antennas have blocked most data transmission from Mount Spurr monitoring stations back to Anchorage. Attempts to reroute and reduce data transmission by prioritizing critical sites provided temporary relief, but continued signal degradation has now impacted these remaining data streams as well. Current data are extremely limited and are insufficient to monitor volcanic signals from Mount Spurr.  



AVO is planning to visit a key repeater on Mount Susitna to assess damage and implement repairs during the next suitable weather window, but the scope of damage is unclear and network restoration may not be possible until the summer field season.  As days lengthen and snowmelt occurs, data transmission could improve sooner. 


Activity and monitoring at Mount Spurr 

This move to UNASSIGNED does not reflect a change in activity at the volcano, but rather a change in AVO’s ability to track volcano activity at Mount Spurr. Though AVO’s monitoring is temporarily compromised, the most probable eruption scenario for Mount Spurr involves several months of intensifying earthquake activity before erupting, and prior to network failure, Mount Spurr was not showing any signs of unrest. 

However, with current monitoring network health, AVO is unable to provide timely eruption forecasts or quickly confirm or dismiss reports of activity. As with other un-instrumented volcanoes, AVO will use satellite data, regional seismic, infrasound and lightning networks, and reports from pilots and ground observers to detect signs of unrest or eruptive activity. These monitoring data may detect ongoing eruptive activity, but AVO will be limited in its ability to identify precursory signals and provide early warning of impending eruptions. 



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