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Spurr

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Leaflet U.S. Department of the Interior | U.S. Geological Survey | Policies

Facts

  • Official Name: Mount Spurr
  • Seismically Monitored: Yes
  • Color Code: YELLOW
  • Alert Level: ADVISORY
  • Elevation: 3374m (11069ft)
  • Latitude: 61.2989
  • Longitude: -152.2539
  • Smithsonian VNum: 313040
  • Pronunciation:
  • 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

    Distance from Anchorage: 78 mi (126 km)

  • Subfeatures:
    • Crater Peak

Description

General physical description:

Mount Spurr is a prominent member of the Cook Inlet volcanoes and is clearly visible from Anchorage on sunny days. The dramatic edifice is made up of several volcanic features. The ancestral Mount Spurr was a large volcano that catastrophically collapsed in early Holocene (post-glacial) time [1] , leaving behind a three-mile-wide caldera with a southeasterly facing breach and a spectacular debris-avalanche deposit in the Chakachatna River valley [1] . Since the collapse, two separate vents have built up their own edifices atop the remains of ancestral Spurr. The current Mount Spurr is a roughly conical lava dome complex [2] (summit elevation 11,070 ft/3,374 m) that rises several thousand feet above the caldera. Crater Peak, the second and more recently active vent, is a stratocone that has grown at the margin of the caldera, within the breach, and has a summit elevation of 7,575 ft (2,309 m) [1] . Mount Spurr and the surrounding caldera are deeply mantled by spectacular glaciers, with fifteen times the ice volume found on Mount Rainier [1] . Crater Peak has erupted explosively twice in the last century [1] and Mount Spurr exhibited a dramatic “ice cauldron” hydrothermal event from 2004 to 2006 [3] . Any future eruption of Mount Spurr or Crater Peak would likely be severely disruptive to Anchorage and the surrounding areas.

Location:

Mount Spurr is the secondmost northeasterly volcano in the Aleutian volcanic arc. It is found at the southernmost end of the Tordrillo Mountains, which are south of the Alaska Range and to the northwest of Cook Inlet [1] . It is bordered to the south by the Chakachatna River valley and to the southwest by the river’s headwaters, Chakachamna Lake, which is partially dammed by Barrier Glacier flowing out of the Tordrillo Mountains [1] . Mount Spurr is 78 miles (126 kilometers) northwest of Anchorage, and the closest community is Beluga, 37 mi (60 km) to the southeast. It is 56 mi (90 km) south of Mount Hayes and 58 mi (93 km) northeast of Redoubt Volcano.

Notable eruptions:

Mount Spurr is notable for several major eruptions and periods of unrest that have occurred in the past 100 years. Crater Peak, the southern vent of Spurr volcano, erupted explosively in 1953 and 1992 [1] . Prior to the 1953 eruption, nearby Alaska residents had sometimes noted steam rising from the peak, which occurred more frequently in late spring 1953 [4] . On July 9, a single powerful explosion about an hour long created a 30,000 ft (10,000 m) high eruption plume [1] . An Air Force jet reported that it flew into the ash cloud for just a moment, but emerged with sandblasted paint and a frosted windscreen [5] , an early example of the dangers of aircraft encounters with volcanic ash. About a quarter inch (6 mm) of ash fell in Anchorage, 78 mi (126 km) away, shutting down Ted Stevens International Airport for two days, and ashfall was reported as far away as Valdez [1] . The eruption also caused pyroclastic flows that mixed with snow and ice and heavy local rainfall to create lahars that temporarily dammed the Chakachatna River [1] .

Seismic monitoring of Mount Spurr began in 1971. Starting in August 1991, increased seismicity was noted beneath Crater Peak. Between November 1991 and June 1992 seismicity increased further beneath the entire Spurr edifice. In mid-June 1992, seismicity increased still further [6] and the small crater lake within Crater Peak rapidly changed color and heated to boiling. The eruption began at 7:04 am June 27 following almost 19 hours of vigorous volcanic tremor and a shallow earthquake swarm under Crater Peak and was quickly reported by a passing Alaska Airlines pilot [7] . This time the eruption plume, which reached 47,500 ft (14,500 m), was blown to the north and 0.04-0.08 in (1-2 mm) of ash fell in Denali National Park. Once again, pyroclastic flows occurred and mixed with snow, ice, and water to form lahars that dammed the Chakachatna. Two more major explosions occurred at Crater Peak on August 18 and September 16-17. Winds carried ash from the August 18 eruption to the east, depositing as much as 0.12 in (3 mm) of ash in Anchorage that closed the Anchorage airport for 20 hours. Ash from the September 16-17 explosion moved in a more northeasterly direction and heavily impacted populated areas in the Matanuska and Susitna valleys [7] .

In 2004, unusual activity was noted at the summit of Mount Spurr, which until then had been thought to be much less likely to erupt than Crater Peak [1] . Several muddy debris flows appeared on the summit’s ice-covered flanks, and snow and ice at the summit melted and collapsed inward to create an “ice cauldron,” a heated crater lake that grew by melting the summit ice from below [2] . The ice cauldron continued to grow for over two years and featured dramatic boiling jets and fumaroles (one dubbed “Jumbo Jet”) before cooling in 2006 and becoming snow covered once again [3] . Addition of new seismic instruments allowed scientists to determine that magma was actually closer to the surface below Mount Spurr summit than below Crater Peak during this period [8] . Earthquake swarms have since occurred in 2012 and 2014-2017, though no eruption has yet followed [9] , [10] , [11] , [12] , [13] .

Several prehistoric eruptions from both vents of Mount Spurr are recorded in ash or tephra layers found in Alaska.

Special hazard info:

Mount Spurr (including Crater Peak) is listed as “very high threat” by the most recent edition of the USGS National Volcanic Threat Assessment [14] . This is because it has erupted frequently in recent history and has shown signs of unrest since its most recent eruption. It is near a large international airport with a high daily passenger volume and would likely disrupt air travel for some time in any future eruption and cut off air access to interior Alaska [14] . Because Mount Spurr is covered with an enormous volume of glacial ice, future eruptions are very likely to cause significant lahars, as happened in 1953 and 1992 [1] . If a lahar dammed the Chakachatna River, the river could back up to Chakachamna Lake and even “float” the ice dam there created by Barrier Glacier, which would likely lead to a very large flood that could reach Cook Inlet. As there are no permanent structures within the Chakachatna valley, this would luckily pose minor risk to people [1] .


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] Preliminary volcano-hazard assessment for Mount Spurr Volcano, Alaska, 2002

Waythomas, C. F., and Nye, C. J., 2002, Preliminary volcano-hazard assessment for Mount Spurr Volcano, Alaska: U.S. Geological Survey Open-File Report 01-0482, 46 p.
full-text PDF 11.25 MB

[2] Geothermal disruption of summit glaciers at Mount Spurr Volcano, 2004-6: an unusual manifestation of volcanic unrest, 2006

Coombs, M.L., Neal, C.A., Wessels, R.L., and McGimsey, R.G., 2006, Geothermal disruption of summit glaciers at Mount Spurr Volcano, 2004-6: an unusual manifestation of volcanic unrest: U.S. Geological Survey Professional Paper 1732-B, 33 p., available at http://pubs.usgs.gov/pp/pp1732/pp1732b/index.html .

[3] 2006 Volcanic activity in Alaska, Kamchatka, and the Kurile Islands: Summary of events and response of the Alaska Volcano Observatory, 2009

Neal, C.A., McGimsey, R.G., Dixon, J.P., Manevich, Alexander, and Rybin, Alexander, 2009, 2006 Volcanic activity in Alaska, Kamchatka, and the Kurile Islands: Summary of events and response of the Alaska Volcano Observatory: U.S. Geological Survey Scientific Investigations Report 2008-5214, 102 p., available at http://pubs.usgs.gov/sir/2008/5214/ .

[4] 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.

[5] Encounters of aircraft with volcanic ash clouds: a compilation of known incidents, 1953-2009, 2010

Guffanti, Marianne, Casadevall, T.J., and Budding, Karin, 2010, Encounters of aircraft with volcanic ash clouds: A compilation of known incidents, 1953-2009: U.S. Geological Data Series 545, ver. 1.0, 12 p., plus 4 appendixes including the compliation database, available only at http://pubs.usgs.gov/ds/545 .

[6] Seismicity and forecasting of the 1992 eruptions of Crater Peak Vent, Mount Spurr volcano, Alaska: an overview, 1995

Power, J. A., Jolly, A. D., Page, R. A., and McNutt, S. R., 1995, Seismicity and forecasting of the 1992 eruptions of Crater Peak Vent, Mount Spurr volcano, Alaska: an overview: in Keith, T. E. C., (ed.), The 1992 eruptions of Crater Peak Vent, Mount Spurr volcano, Alaska, U.S. Geological Survey Bulletin 2139, p. 149-159.
full-text PDF 322 KB

[7] The 1992 eruptions of Crater Peak Vent, Mount Spurr volcano, Alaska: chronology and summary, 1995

Eichelberger, J. C., Keith, T. E. C., Miller, T. P., and Nye, C. J., 1995, The 1992 eruptions of Crater Peak Vent, Mount Spurr volcano, Alaska: chronology and summary: in Keith, T. E. C., (ed.), The 1992 eruptions of Crater Peak Vent, Mount Spurr volcano, Alaska, U.S. Geological Survey Bulletin 2139, p. 1-18.
full-text PDF 560 KB

[8] Fluid ascent during the 2004-2005 unrest at Mt. Spurr inferred from seismic tomography, 2013

Koulakov, I., West, M., and Izbekov, P., 2013, Fluid ascent during the 2004-2005 unrest at Mt. Spurr inferred from seismic tomography: Geophysical Research Letters, v. 40, doi:10.1002/grl.50674 .

[9] 2012 Volcanic activity in Alaska: Summary of events and response of the Alaska Volcano Observatory, 2014

Herrick, J.A., Neal, C.A., Cameron, C.E., Dixon, J.P., and McGimsey, R.G., 2014, 2012 Volcanic activity in Alaska: Summary of events and response of the Alaska Volcano Observatory: U.S. Geological Survey Scientific Investigations Report 2014-5160, 82p., http://dx.doi.org/10.3133/sir20145160.

[10] 2014 Volcanic activity in Alaska - Summary of events and response of the Alaska Volcano Observatory, 2017

Cameron, C.E., Dixon, J.P., Neal, C.A., Waythomas, C.F., Schaefer, J.R., and McGimsey, R.G., 2017, 2014 Volcanic activity in Alaska - Summary of events and response of the Alaska Volcano Observatory: U.S. Geological Survey Scientific Investigations Report 2017-5077, 81 p., https://doi.org/10.3133/sir20175077.
full-text PDF 6.8 MB

[11] 2015 Volcanic activity in Alaska - Summary of events and response of the Alaska Volcano Observatory, 2017

Dixon, J.P., Cameron, C.E., Iezzi, A.M., and Wallace, Kristi, 2017, 2015 Volcanic activity in Alaska-Summary of events and response of the Alaska Volcano Observatory: U.S. Geological Survey Scientific Investigations Report 2017-5104, 61 p., https://doi.org/10.3133/sir20175104.

[12] 2016 Volcanic activity in Alaska - Summary of events and response of the Alaska Volcano Observatory, 2020

Cameron, C.E., Dixon, J.P., Waythomas, C.F., Iezzi, A.M., Wallace, K.L., McGimsey, R.G., and Bull, K.F., 2020, 2016 Volcanic activity in Alaska-Summary of events and response of the Alaska Volcano Observatory: U.S. Geological Survey Scientific Investigations Report 2020-5125, 63 p., https://doi.org/10.3133/sir20205125.

[13] 2017 Volcanic activity in Alaska-Summary of events and response of the Alaska Volcano Observatory, 2020

Dixon, J.P., Cameron, C.E., Iezzi, A.M., Power, J.A., Wallace, K., and Waythomas, C.F., 2020, 2017 Volcanic activity in Alaska-Summary of events and response of the Alaska Volcano Observatory: U.S. Geological Survey Scientific Investigations Report 2020-5102, 61 p., https://doi.org/10.3133/sir20205102.

[14] 2018 update to the U.S. Geological Survey national volcanic threat assessment, 2018

Ewert, J.W., Diefenbach, A.K., and Ramsey, D.W., 2018, 2018 update to the U.S. Geological Survey national volcanic threat assessment: U.S. Geological Survey Scientific Investigations Report 2018-5140, 40 p., https://pubs.usgs.gov/sir/2018/5140/sir20185140.pdf.

Current Activity

May 27, 2025, 11:06 am

Unrest continues at Mount Spurr volcano. Small volcanic earthquakes were detected beneath the volcano over the past day. No unusual activity was observed in partly cloudy satellite views over the past day. Web camera view were mostly obscured by cloudy conditions, but occasional clear views showed no unusual activity.


Although low-level unrest continues, no changes have been observed in the monitoring data to indicate that the volcano is moving closer to an eruption. Based on previous eruptions, changes from current activity in the earthquakes, ground deformation, summit lake conditions, and fumarolic activity would be expected if magma began to move closer to the surface. Therefore, if an eruption occurred, it would be preceded by additional signals allowing warning.

 

The volcano is monitored using local seismic, infrasound, web camera, and GNSS (GPS) stations along with regional infrasound, lightning networks, and satellite data.

Recent Updates

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Webicorder

Geodesy Sensors

Color Code Timeline

Reported Activity

Modern Eruptions

Westdahl

Westdahl Eruption Timeline

Westdahl 1795

1795

From Miller and others (1998): "Veniaminov (1840, p. 18) described an eruption in 1795 on the southwest end of Unimak Island, which most likely occurred at Westdahl. Coats (1950) attributed four eruptions in the late eighteenth century and early nineteenth century to Pogromni volcano. Based on recent observations from aircraft, however, Pogromni does not appear to have been active in historical time. The eruptions should probably be assigned to Westdahl."
From Veniaminov (1840, translated by Lydia T. Black and R.H. Geoghegan, 1984): "In regard to volcanic phenomena, Unimak Island has occupied the first place since antiquity, both for its extraordinary size or the height and position of the mountains located on it. About 1795, with the wind from the SW, the range on the SW end of Unimak blew up with a terrible thunder and an eruption of ash [pepel] or soot [sazha], white in color, in such a great quantity that, for several hours in the middle of the day, not only in the neighboring villages on Aliaksa but even on Unga, there was absolute darkness. The eternal ice, lying on that range, slid down along both sides together with a large quantity of water and burned rocks of different sizes. The last stopped about half-way along and formed a trench or a black belt visible even now. There are still signs in places where the water flows and where the ice, which had slid down the mountain, rested for several years (the vegetation has only just begun to appear there). Nowadays one notices that this very range, which had been at rest after the upheaval, in the last few years, in one place, began to grow or bulge out."
Additionally, Plummer (1898) reports that the southwest crater exploded and fell in.
Sapper (1927) assigns this eruption to his category b1, and estimates more than 1 cubic km (10^9 cubic m) of tephra was erupted.

Westdahl 1796

1796

From Miller and others (1998): "Coats (1950) attributed four eruptions in the late eighteenth century and early nineteenth century to Pogromni volcano. Based on recent observations from aircraft, however, Pogromni does not appear to have been active in historical time. The eruptions should probably be assigned to Westdahl."
Sapper (1917) reports that in 1796 ice and water came pouring down to a town called Nosowskoi. Coats (1950) reports a lava flow or plug dome and some explosive activity.
Simkin and Siebert (1994) assign the eruption a VEI of 0, indicating a non-explosive eruption.

Westdahl 1820

1820

From Miller and others (1998): "Coats (1950) attributed four eruptions in the late eighteenth century and early nineteenth century to Pogromni volcano. Based on recent observations from aircraft, however, Pogromni does not appear to have been active in historical time. The eruptions should probably be assigned to Westdahl."
The eruption of 1820 is a little more confusing, as reports are unclear as to whether the event occurred on Unimak Island (containing the volcanoes of Westdahl, Pogromni, Fisher Caldera, Shishaldin, Isanotski, and Roundtop) or Umnak Island (containing the volcanoes Okmok, Recheshnoi, and Vsevidof). Modern compilers have attributed this event to Westdahl.
Soloviev and Go (1972) report: "1820, March 1 or the night of 2-3. A powerful volcanic eruption occurred on the northern tip of Umnak Island. The ashes spread as far as Unalaska and Unimak Islands. The eruption was accompanied by a strong earthquake. 'At dawn, it was observed that the sea had become more agitated' (Perrey, 1865 [in French])." Lander (1996) attributes this eruption to Pogromni, which is on southwest Unimak Island. Okmok Volcano is on the northeast of Umnak Island.
Lander (1996) writes "1820, March 1-2. Due to a strong eruption of Pogromni Volcano on the northern tip of Umnak Island [typographical error? Pogromni and Westdahl are on the southwestern side of Unimak Island], ashes injected into the air were observed as far away as Unalaska and Unimak [Another error? Westdahl and Pogromni are on Unimak] Islands. There was a strong earthquake on the night of March 1. The sea was observed to have became highly disturbed by dawn (Soloviev and Go, 1975: in Russian). Mushketov and Orlov (1893, p. 207-208: in Russian) describe the eruption has having taken place on February 19-20 (March 1-2 in Gregorian date) and another account dated March 1 referring to ash fall clouding the sea. Although the highly disturbed sea is suggestive of a tsunami, there is no specific mention of waves."
Mushketov and Orlov (1893, translated in 1994 by Katherine Arndt) wrote: "In 1820, on 19 February (Old Style) (in the night on the 20th), in a severe SE wind, on certain islands of the Aleutian Archipelago there were felt strong tremblings of the earth with a subterranean rumble. Immediately after, the air, it seemed, caught fire and clouds of ash and sand began to fall during the whole night. With the approach of day the wind changed, the volcanic matter stopped falling, but the sea was highly agitated. At the same time as these phenomena occurred on Unalaska, the volcano of Urimak [sic] Island, located 197 kilometers from Unalaska, began to produce eruptions which continued until August. (According to Postels, the active volcano was located on the north end of Umnak Island.) People who set out to look for the crater, due to the stinking steams tha thad spread for a verst, could not approach it and were convinced only that the island had increased in size and that the sea had rushed back for a considerable distance. Volcanic products erupted in such quantity that Urimak Island was covered with them for a radius of three miles around the crater. Postels describes these phenomena in the following manner: on 1 March on the north end of Umnak Island there occurred an eruption in which the ash reached Unalaska and Unimak. A strong earthquake, accompanied by a severe storm from the SE, plunged the inhabitants of Unalaska into terror. With the rising of the sun they saw that in certain places the earth was covered with ash more than a foot deep; the springs were choked with it, [and] the sea became cloudy, so that for a whole year fish were not seen in it and even whales appeared more rarely than usual. Not far from the site of eruption the Aleuts found amber in the loosened earth which covered the cliff that is washed by the lake." Mushketov and Orlov cite Malte Brun, Nouv. annales des voyages, XV, p. 131; Arago, Ann. de chimie et de phys., XXI, p. 396; and Postels, Voyage autour du monde, III, p. 24."
Coats (1950) reports a minor explosive eruption and Powers (1958) reports an ash eruption.

Westdahl 1827/3

March 1827 — 1829

From Miller and others (1998): "Coats (1950) attributed four eruptions in the late eighteenth century and early nineteenth century to Pogromni volcano. Based on recent observations from aircraft, however, Pogromni does not appear to have been active in historical time. The eruptions should probably be assigned to Westdahl."
Grewingk (1850, translated 2003 by Fritz Jaensch) reports that Isenbeck said that Pogromnaia was belching fire in 1827, and "Lastly, on the southern side of Unimak, on the west side of Tugamak Gulf [Unimak Bight], the location of which is not accurately fixed, but probably not far from Pogromnoi Volcano, there, in September of 1827, according to the log of the corvette Moller, a 'lava brulante' was observed, meaning most likely a not-yet-cooled lava stream. Dr. Isenbeck reports (oral report) that during the passage through the Strait of Unimak, a fiery column constantly ascended from the volcano closest to the coast. This was probably Pogromnoi Volcano, although Veniaminov's indications, according to which the Shishaldin erupted at the same time, speak against it."
Powers (1958) reports an ash eruption.

Westdahl 1830

1830

From Miller and others (1998): "Coats (1950) attributed four eruptions in the late eighteenth century and early nineteenth century to Pogromni volcano. Based on recent observations from aircraft, however, Pogromni does not appear to have been active in historical time. The eruptions should probably be assigned to Westdahl."
Petroff (1884) reports an eruption in autumn of 1830, but Grewingk (1850, translated 2003 by Fritz Jaensch) suggests the eruption is from Shishaldin. Becker (1898) lists an 1830 eruption with ashes.

Westdahl 1951/7

July 5, 1951 — July 7, 1951

From Miller and others (1998): "Based on recent observations from aircraft, however, Pogromni does not appear to have been active in historical time. The eruptions should probably be assigned to Westdahl."
Jones (1952) reports that an officer of one of the TAKL ships reported that Pogromni volcano was not active on July 2, but it was smoking on July 5 to 7.

Westdahl 1964/3

March 10, 1964 — April 16, 1964

Juergen Kienle's compiled notes on file at the Geophysical Institute, University of Alaska Fairbanks, state that Skinner reported in 1979 that during late 1964 to early 1965, 7 separate "blow holes" of ash on E-W line were active at Westdahl. He also states that across a plateau south of Pogromni, just before it slopes off to Bering Sea, there was activity for 1 week, there was a deep gully connecting all blow holes in snow field, and at the end of the week, the main fissure had completely stopped, but a new cone had formed 3 miles from the Bering Sea beach (with lava flow).
Reeder and Doukas (1994) report that Westdahl erupted in 1964-65, producing a fissure-fed lava flow that eventually covered 35 square kilometers.
Coats (1964) writes that tremors were reported at Scotch Cap, and that although there was lava, the composition is unknown. Coarse tephra was also produced. On April 16, the vent was only steaming slightly. Secondary fumaroles were seen on the lava flow.
The Associated Press produced an article on March 14, 1964: "A major new volcanic eruption was reported late Friday on Unimak Island in the Aleutian chain, with a two-mile river of lava flowing from the mountain's crater and debris hurled 2,000 feet into the air.
"The lava flow and spewing debris was reported by a Coast Guard plane flying a low-level survey about five miles east of Westdahl peak, on Pogromni volcano at the west end of Unimak."

Westdahl 1978/2

February 4, 1978 — February 9, 1978

Around 1:15 pm on February 4, 1978, Clark (1978) observed "great billowing clouds of steam with a drifting black backdrop that suggested falling ash. * * * This was accompanied by lightning, thunder and the smell of sulphur. * * * By 4:00 pm the cloud had become much broader and dark * * * and Clark observed 'swaths of melting snow coming down the hillside.' By 4:30 pm the ash was thick at Scotch Cap. At 6:45 pm Clark 'experienced hail; small stones. The stones are dark. The ash has actually been seeding the clouds! We have noticed small bits of cinder from the cores of the hailstones.' At 7:35 pm a foot of ash had built up. At 11:35 pm lightning continued, and appeared red. Hail and cinder storms continued on and off at Scotch Cap, along with lightning and thunder, until the afternoon of February 5, when the cloud traveled to the southwest. Clark also reports, on February 6, that the road from Scotch Cap to Cape Serichef was washed out, leaving a 30 foot drop off, at least 100 yards across.
From Krafft and others (1980): The U.S. Coast Guard reported on 6 February that ash, accompanied by a sulfur odor, was falling on a station located at the foot of Westdahl. Lightning was observed above the summit, accompanied by thunder and rumbling. Reeve Aleutian Airways personnel report an ash cloud rising to 8,000 -10,000 m altitude, including some large blocks visible above the 3000 m cloud layer. Snow contaminated by dark ash fell on the freight vessel UNITED SPIRT between 12:00 and about midnight on 7 February, as it steamed from 48.8 degrees N, 152.5 degrees W to 49.2 degrees N, 156.3 degrees W, about 1000 km SE of Westdahl. A plume was visible in a satellite image taken at 1129 on 9 February. After the 9th, activity declined to steaming. The new crater formed by the February eruption is about 1.5 km in diameter and 0.5 km deep, located at about 1450 m elevation. Its upper portion cuts through glacial ice, which reaches a thickness of 200 m on the N rim. The bottom of the vertical-walled crater is filled with blocks, ash, ice, and talus. A lahar deposit, originating on the WSW flank of the new crater, extends down the glacier on Westdahl's flank to the sea, cutting the road from Cape Sarichef to Scotch Cap. The thickness of the upper portion of the deposit averages about 50 cm, increasing to 1-3 m near the lower end (Data from: SEAN Bulletin, vol. 3, n. 1, p. 7, n.2, p. 3-6, n. 9, p. 9-11)."

Westdahl 1979/2

February 8, 1979 — February 9, 1979

From Pamenter and Kienle (1981): "Ash cloud about 8 km high. "A cloud apparently erupted from Westdahl was present on NOAA weather satellite imagery for more than 30 hours on 8 and 9 February. The cloud was first observed on an infrared image taken at 03:52 on 8 February, about 17 hours after the previous image, on which no eruption cloud could be seen. It occurred on 08:42 and 10:37 (infrared) but was not present at 19:58 on the 9th of 09:52 on the 10th. The cloud was no more than 50 km in longest dimension on any of the images, nor was it elongated into a typical volcanic plume. The height of the cloud was calculated separately from infrared and visual images taken at 09:26 on 8 February. Analysis of the infrared image gives a temperature of -53 degrees C at the top of the cloud, corresponding to an altitude of slightly more than 8 km. On the visual image, measurements of the shadow cast on the weather cloud deck by the volcanic cloud results in an estimated altitude of 7.7 +/- 1 km (Data from SEAN Bulletin, vol. 4, p. 2-3, 1979)."

Westdahl 1991/11

November 29, 1991 — January 15, 1992

McGimsey and others (1995): ""A steam and ash cloud rising to more than 6 km above Westdahl volcano [see fig. 36-1 in original text] was first reported by commercial pilots on routine flights along the Aleutian Island chain on November 29, 1991 (BVE no. 31, p. 83-86). The next day, pilots reported eruptive activity along an 8-km-long fissure that extended from Westdahl Peak northeastward across the glaciated summit area [see fig. 36-2 in original text]. Many pits, craters, and gaping cracks were visible in the ice adjacent to the fissure. In addition to ash and steam venting, spectacular lava fountains along the lower few kilometers of the fissure fed a lava flow that extended 7 km from the vent and was as much as 1.5 km wide at the front and 5-10 m thick. An AVO crew aboard a Coast Guard C-130 observed the lava flow on December 3 as well as the still-steaming deposits of a lahar that had advanced 18 km from the vent to enter the sea. Stormy weather conditions prevented direct observation of the vent area for most of December, 1991, but pilots reported a constant steam plume, usually mixed with ash, punching through the weather cloud cover. Residents of False Pass, the nearest permanent settlement, 90 km NE of Westdahl Peak, also reported thunder-like rumbling sounds, the occasional smell of sulfur, and light ashfalls on November 30, December 16, 25, and 26 - evidence that the eruption was still continuing. Steam clouds rose to almost 5 km altitude on January 2-3, 1992. Ash clouds observed on January 8-9 reached 2.4 km altitude. Satellite images during the late afternoon of January 9 showed the plume extending about 150 km SE. By January 15, there was no sign of a vertical plume or any other eruptive activity. Also by mid-January, the lava flow viewed on December 3, 1991 had not advanced, but had widened to cover an area about 2-3 times greater than in December [see fig. 36-3 in original text]."
Siebert and Simkin (2002-) estimate this eruption produced 5x10^7 cubic meters of lava.

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Westdahl 1996/3

March 1, 1996

From Neal and McGimsey (1997): "AVO detected a plume-like cloud with a negative Band 4-5 signature on an AVHRR image of Unimak Island on the morning of March 1, 1996. Subsequent analysis with NWS colleagues and lack of any confirmation of an eruption by pilots let to the conclusion that the cloud was meterologic in nature. The cloud suggested possible activity at Westdahl, which makes up much of the southwest portion of Unimak Island, 50 miles west of False Pass and 125 miles northeast of Akutan."

Westdahl 2004/1

January 7, 2004

From Neal and others (2005): "On January 7, 2004, 90 earthquakes occurred over a period of 12 hours beneath Westdahl Volcano on Unimak Island in the eastern Aleutians. Since the short-period seismic network was installed on this volcano in 1998, the majority of background seismicity has occurred in the vicinity of Faris Peak, a young, intracaldera cone 4 km (2.5 mi) east-northeast of Westdahl Peak (fig. 21B.) The 2004 swarm consisted of earthquakes ranging in size from ML (local or Richter magnitude) = 0.2 to ML = 1.6. The largest earthquakes (ML = 1.6) occurred during the second half of the swarm. Depths ranged from sea level to 8 km (5 mi) below sea level. Over the next 10 months, AVO detected several deep, long-period events below the volcano. Given the location of this swarm beneath the general area of the most recent historical eruptions and the subsequent swarm of deep, long-period earthquakes, this seismicity most likely represents a magmatic intrusion. Due to the short duration and abrupt termination of this swarm, AVO did not raise the level of concern color code for Westdahl, nor did AVO mention the activity in its weekly updates."

Westdahl non-eruptive activity 2008

January 1, 2008

From Cameron and others, 2023: "Throughout 2018, Westdahl volcano (an informal name that herein includes Westdahl Peak, Westdahl caldera, and associated intra- and extra-caldera features) continued its long-term steady inflation, which has persisted since the deformation was first observed after the installation of a GPS network on Unimak Island in 2008. An analysis of Westdahl volcano InSAR data by Lu and others (2003) indicated a shallow magma reservoir exists beneath the volcano; the continued inflation is consistent with an ongoing accumulation of magma at shallow depths. Westdahl volcano remained at GREEN and NORMAL throughout 2018."
From Orr and others, 2023: "In 2019, Westdahl volcano continued its long-term trend of steady inflation, which has persisted since the trend was first observed after the installation of a GNSS network on Unimak Island in 2008. An analysis of Westdahl volcano InSAR data by Lu and others (2003) indicated a magma reservoir exists beneath the volcano at a depth of about 6 km [3.7 mi] below sea level. Continued inflation of Westdahl volcano is consistent with an ongoing accumulation of melt at relatively shallow depths. The volcano remained at GREEN and NORMAL throughout 2019."

Westdahl 2010/7

July 2010

From Neal and others (2014): "In late July, AVO seismologists noted a marked increase in lower crustal seismicity at Westdahl. Most of the seismicity was long period in character however some volcano-tectonic events also were recorded.
Deep (>10 km or >6.2 mi), low frequency events located with the Westdahl seismograph network tend to cluster in an area northwest of the volcano's summit. Past analysis of InSAR results for Westdahl by Lu and others (2003) suggests a shallow magma reservoir beneath the volcano. Continued inflation of the volcano is consistent with ongoing accumulation of melt at shallow levels. Such ascent of magma from depth may explain the 2010 seismicity at Westdahl."

Westdahl 1795

Westdahl 1796

Westdahl 1820

Westdahl 1827/3

Westdahl 1830

Westdahl 1951/7

Westdahl 1964/3

Westdahl 1978/2

Westdahl 1979/2

Westdahl 1991/11

Westdahl 1996/3

Westdahl 2004/1

Westdahl non-eruptive activity 2008

Westdahl 2010/7

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TimelineJS

22 Event Date(s)

Past Activity Legend:
Eruption
Questionable eruption
Non-eruptive activity


Showing 1 - 20 of 692

Map Images

Map References

Recently active volcanoes of Alaska, 2023

Cameron, C.E., Bull, K.F., and Macpherson, A.E., 2023, Recently active volcanoes of Alaska: Alaska Division of Geological & Geophysical Surveys Miscellaneous Publication 133 v. 6, 2 sheets. https://doi.org/10.14509/31086.

Tephra occurrence in Alaska: a map-based compilation of stratigraphic tephra data, 2018

Worden, A.K., Schaefer, J.R., and Mulliken, K.M., 2018, Tephra occurrence in Alaska: a map-based compilation of stratigraphic tephra data: Alaska Division of Geological and Geophysical Surveys Miscellaneous Publication 165, 19 p., http://doi.org/10.14509/30059

Historically active volcanoes of Alaska, v. 3, 2018

Cameron, C.E., Schaefer, J.R., and Mulliken, K.M., 2018, Historically active volcanoes of Alaska: Alaska Division of Geological & Geophysical Surveys Miscellaneous Publication 133 v. 3, 2 sheets. Http://doi.org/10.14509/30142

Historically active volcanoes of Alaska, 2014

Schaefer, J.R., Cameron, C.E., and Nye, C.J., 2014, Historically active volcanoes of Alaska: Alaska Division of Geological & Geophysical Surveys Miscellaneous Publication 133 v. 1.2, 1 sheet, scale 1:3,000,000. This publication has been superseded. Newest version available at http://www.dggs.alaska.gov/pubs/id/20181 .

Preliminary geologic map of the Cook Inlet Region, Alaska - including parts of the Talkeetna, Talkeetna Mountains, Tyonek, Lake Clark, Kenai, Seward, Iliamna, Seldovia, Mount Katmai, and Afognak 1:250,000-scale Quadrangles, 2009

Wilson, F.H., Hults, C.P., Schmoll, H.R., Haeussler, P.J., Schmidt, J.M., Yehle, L.A., and Labay, K.A., compilers; digital files prepared by Wilson, F.H., Hults, C.P., Labay, K.A., and Shew, Nora, 2009, Preliminary geologic map of the Cook Inlet Region, Alaska - including parts of the Talkeetna, Talkeetna Mountains, Tyonek, Lake Clark, Kenai, Seward, Iliamna, Seldovia, Mount Katmai, and Afognak 1:250,000-scale Quadrangles: U.S. Geological Survey Open-File Report 2009-1108, scale 1:250:000, available at http://pubs.usgs.gov/of/2009/1108/ .

Historically active volcanoes of the Aleutian Arc, 2002

Schaefer, Janet, and Nye, C. J., 2002, Historically active volcanoes of the Aleutian Arc: Alaska Division of Geological & Geophysical Surveys Miscellaneous Publication MP 0123, unpaged, 1 sheet, scale 1:3,000,000. Superceded by Miscellaneous Publication 133: http://www.dggs.dnr.state.ak.us/pubs/pubs?reqtype=citation&ID=20181

World map of volcanoes and principal aeronautical features, 1999

Casadevall, T. J., Thompson, T. B., and Fox, Tom, 1999, World map of volcanoes and principal aeronautical features: U.S. Geological Survey Miscellaneous Investigations Series Map I 2700, unpaged, 1 plate, scale 1:34,268,000.

Volcanoes of Alaska, 1998

Nye, C. J., Queen, Katherine, and McCarthy, A. M., 1998, Volcanoes of Alaska: Alaska Division of Geological & Geophysical Surveys Information Circular IC 0038, unpaged, 1 sheet, scale 1:4,000,000, available at http://www.dggs.dnr.state.ak.us/pubs/pubs?reqtype=citation&ID=7043 .
Hard Copy held by AVO at FBKS - CEC shelf

Snow and ice volume on Mount Spurr Volcano, Alaska, 1981, 1997

March, Rod, Mayo, L. R., and Trabant, Dennis, 1997, Snow and ice volume on Mount Spurr Volcano, Alaska, 1981: U.S. Geological Survey Water-resources investigations report WRI 97-4142, 36 p., 2 plates, scale 1:50,000.
Hard Copy held by AVO at FBKS - CEC shelf

Catalog and initial analyses of geologic data related to middle and late Quaternary deposits, Cook Inlet region, Alaska, 1996

Reger, R. D., Pinney, D. S., Burke, R. M., and Wiltse, M. A., 1996, Catalog and initial analyses of geologic data related to middle and late Quaternary deposits, Cook Inlet region, Alaska: Alaska Division of Geological & Geophysical Surveys Report of Investigation 95-06, 188 p., 6 sheets, scale 1:250,000.
Hard Copy held by AVO at FBKS - CEC shelf

Volcanoes of Alaska, 1995

Alaska Division of Geological & Geophysical Surveys, 1995, Volcanoes of Alaska: Alaska Division of Geological & Geophysical Surveys Information Circular IC 0038, unpaged, 1 sheet, scale 1:4,000,000.

Aleutian arc volcanoes, 1994

Nye, C. J., 1994, Aleutian arc volcanoes: Alaska Division of Geological & Geophysical Surveys Public-Data File PDF 94-54, unpaged, 1 sheet, scale 1:2,126,841.

This dynamic planet: world map of volcanoes, earthquakes, impact craters, and plate tectonics, 1994

Simkin, Tom, Unger, J. D., Tilling, R. I., Vogt, P. R., and Spall, H. R., 1994, This dynamic planet: world map of volcanoes, earthquakes, impact craters, and plate tectonics: U.S. Geological Survey Special Map unpaged, 1 plate, scale 1:30,000,000.

Geothermal resources of the Aleutian Arc, 1993

Motyka, R. J., Liss, S. A., Nye, C. J., and Moorman, M. A., 1993, Geothermal resources of the Aleutian Arc: Alaska Division of Geological & Geophysical Surveys Professional Report PR 0114, 17 p., 4 sheets, scale 1:1,000,000.
Hard Copy held by AVO at FBKS - CEC shelf

Holocene volcanoes of the Aleutian Arc, Alaska, 1993

March, G. D., 1993, Holocene volcanoes of the Aleutian Arc, Alaska: Alaska Division of Geological & Geophysical Surveys Public-Data File PDF 93-85, unpaged, 1 sheet, scale 1:2,000,000.

Geothermal energy resource investigations at Mt. Spurr, Alaska, 1986

Turner, D.L., and Wescott. E.M. (eds.), 1986, Geothermal energy resource investigations at Mt. Spurr, Alaska: University of Alaska Fairbanks Geophysical Institute Report UAG-R 308, 98 p., 5 plates, scale 1:2,860 and 1:6,250.
full-text PDF 9.33 MB
plate 1-1 9.6 MB
plate 5-1 4.91 MB
plate 5-2 5.71 MB
plate 6-1 47.1 MB
Hard Copy held by AVO at FBKS - CEC file cabinet

The Mt. Spurr, Alaska Geothermal Energy Assessment Project: introduction, geologic overview and present geothermal manifestations, 1986

Turner, D. L., Nye, C. J., Beget, J. E., and Wescott, E. M., 1986, The Mt. Spurr, Alaska Geothermal Energy Assessment Project: introduction, geologic overview and present geothermal manifestations: 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. 7-19, 1 plate, scale 1:2,860.

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.
Hard Copy held by AVO at FBKS - CEC file cabinet

Map showing distribution, composition, and age of Late Cenozoic volcanic centers in Alaska, 1986

Luedke, R. G., and Smith, R. L., 1986, Map showing distribution, composition, and age of Late Cenozoic volcanic centers in Alaska: U.S. Geological Survey Miscellaneous Investigations Series Map I 1091-F, unpaged, 3 sheets, scale 1:1,000,000.

Mercury and helium soil surveys at Mt. Spurr, Alaska, 1986

Turner, D. L., Wescott, E. M., and Bratt, D., 1986, Mercury and helium soil surveys 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. 66-79, 2 plates, scale 1:6,250.

Electrical geophysical surveys for potential geothermal reservoirs on the south side of Mt. Spurr, Alaska, 1986

Wescott, E. M., Witte, W., Moore, P., and Turner, D. L., 1986, Electrical geophysical surveys for potential geothermal reservoirs on the south side of 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. 41-65, 1 plate, scale 1:2,860.

Geologic map of Alaska, 1980

Beikman, H. M., 1980, Geologic map of Alaska: U.S. Geological Survey Professional Paper PP 0171, unpaged, 1 plate, scale 1:2,500,000.

Quaternary geology of Alaska, 1975

Pewe, T. L., 1975, Quaternary geology of Alaska: U.S. Geological Survey Professional Paper PP 0835, 145 p., 3 sheets, scale 1:5,000,000.
full-text PDF 7.6 MB
plate 1 PDF 2.3 MB
table 2 PDF 277 KB
table 3 PDF 232 KB

Glacier dammed lakes and outburst floods in Alaska, 1971

Post, A., and Mayo, L. R., 1971, Glacier dammed lakes and outburst floods in Alaska: U.S. Geological Survey Hydrologic Investigations Atlas HA 0455, 10 p., 1 sheet, scale 1:1,000,000.

Some effects of recent volcanic ash falls with special reference to Alaska, 1959

Wilcox, R. E., 1959, Some effects of recent volcanic ash falls with special reference to Alaska: in Investigations of Alaskan volcanoes, U.S. Geological Survey Bulletin 1028-N, p. 409-476, 5 sheets, scale unknown.
full-text PDF 1.5 MB
plate 54 PDF 76 KB
plate 55 PDF 194 KB
plate 56 PDF 234 KB
plate 57 PDF 177 KB
plate 58 PDF 140 KB
Hard Copy held by AVO at FBKS - CEC shelf

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
Hard Copy held by AVO at FBKS - CEC shelf

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Before an eruption

Ashfall & Preparedness Information

During and After an Eruption

Other Useful Links

Ash Forecasting

Mathematical models developed by the USGS forecast various aspects of how a volcanic ash plume will interact with wind—where, how high, and how fast ash particles will be transported in the atmosphere, as well as where ash will fall out and accumulate on the ground. AVO runs these models when a volcano is restless by assuming a reasonable hypothetical eruption, to provide a pre-eruptive forecast of areas likely to be affected. During an ongoing eruption, AVO will update the forecast with actual observations (eruption start time and duration, plume height) as they become available.

View the current airborne ash cloud models for Spurr

Ashfall thickness forecast

The Ash3d model was developed by the USGS to forecast how a volcanic ash plume will interact with wind and where ash will fall out and accumulate on the ground. AVO runs these models twice daily when a volcano is restless by assuming a reasonable hypothetical eruption altitude and duration. The map shows the model results of ashfall thickness for areas that are likely to be affected, if one were to occur. During an ongoing eruption, AVO will update the forecast with actual observations (eruption start time and duration, plume height) as they become available, and these plots will be automatically updated. The National Weather Service Anchorage Forecast Office will issue the official ashfall warning product and post them at weather.gov/afc

THESE PRODUCTS MAY NOT BE CURRENT.

During an actual eruption, see National Weather Service forecasts of ashfall:https://weather.gov/afc.

Ashfall Forecast

Click on the X on the graphic (upper right) to expand the map to show the map legend.

Ashfall Start Time

This map shows the modeled estimate of the time it would take for ashfall to begin following an eruption. It corresponds to the ashfall thickness forecast map shown above. This map uses the start time of either the twice-daily hypothetical model runs (time shown in the legend) or the actual eruption start time (if one were to occur). In the case of an actual eruption, the National Weather Service Anchorage Forecast Office will issue the official ashfall warning product that includes the ashfall start time and post them at weather.gov/afc

THESE PRODUCTS MAY NOT BE CURRENT.

During an actual eruption, see National Weather Service forecasts of ashfall:https://weather.gov/afc.

Ashfall Start Times Forecast

Click on the X on the graphic (upper right) to expand the map to show the map legend.

Ashfall likelihood maps

These maps show the areas that could experience ashfall if an explosive eruption of Mount Spurr were to occur. They show the area of “disruptive” ashfall where at least 100 g/m2 (0.3 oz/ft2) of ash could fall (in color), and a larger area where “perceptible” ashfall of 10 g/m2 (0.03 oz/ft2) could occur (as a dashed line).

Three ashfall likelihood maps are produced daily and provide ashfall forecasts for the current day, the next day, and two days later. These are intended to be used for situational awareness and planning purposes. Each map is based on 48 simulations using the USGS Ash3d model. The simulations vary the eruption start time and eruption cloud altitude using observations of three explosive events at Spurr in 1992 as guidance.

“High likelihood” areas are impacted in 66-100% of the simulations, “Medium Likelihood” areas are impacted in 33-66% of the simulations (25–50%); and “Low Likelihood” areas are impacted in 5-33% of the simulations.

Day 1
Day 2
Day 3

What is the relationship between mass and deposit thickness?

The Ash3d model determines areas affected based on ashfall in units of mass per unit area (g/m2 or oz/ft2). Two ash deposits with the same mass per unit area but different densities will have different thickness: a denser ash deposit will be thinner than a less dense deposit of the same mass per unit area. We will not know the density until after an eruption starts and ashfall occurs, so a range of deposit thicknesses are given.

What can I expect from “disruptive” ash?

The “disruptive” ashfall maps show how likely it is for areas to receive at least 100 g/m2 (0.3 oz/ft2) of ash given the forecasted wind conditions. This threshold for potentially disruptive ashfall is based on case studies from around the world. A mass per unit area of 100 g/m2 corresponds to an ash deposit that is approximately 0.1 to 1 mm (0.004–0.04 inches) thick, depending on the deposit density and whether it has been compacted by rain or snow.

It is important to note that the threshold is a minimum value. The ash deposit from an actual eruption would likely be much greater closer to the volcano, and in populated areas. For example, the ash deposit in Anchorage from the August 1992 eruption of Mount Spurr was 10-20 times greater than the threshold used in the maps. Ashfall in Anchorage from the 1953 eruption was about twice that of 1992, and in both cases it was sufficient to block out the sun for several hours across Cook Inlet, turning day into “night”.

In general, the thicker the ashfall, the more problems it will cause on the ground, especially in populated areas. The 1992 ashfall closed the Anchorage airport for almost a day until it could be cleared, and presented air quality problems for months as the ash was resuspended by winds and vehicle traffic. A variety of other impacts are possible including abrasive damage to mechanical equipment, and disruptions to electrical service. Detailed information and photos of ashfall impacts and how to mitigate them is available through the Volcanic Ashfall Impacts Working Group.

What can I expect from “perceptible” ash?

The area of “perceptible” ashfall is shown on the maps using a dashed line and shows the area where 10 g/m2 (0.03 oz/ft2) of ashfall was in 5% of model runs. A mass per unit area of 10 g/m2 corresponds to an ash deposit that is at least 0.01 mm (0.0004 inches) thick, depending on the deposit density and whether it has been compacted by rain or snow. This amount of ash is noticeable to the naked eye and will be most apparent on surfaces that have a different color than the ash or are reflective and smooth, like snow or cars.

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