Wrangell

Photo of this volcano
  • United States
  • Alaska
  • Shield
  • 2002 CE
  • Country
  • Volcanic Region
  • Primary Volcano Type
  • Last Known Eruption
  • 62.006°N
  • 144.017°W

  • 4278 m
    14032 ft

  • 315020
  • Latitude
  • Longitude

  • Summit
    Elevation

  • Volcano
    Number

Most Recent Bulletin Report: April 1986 (SEAN 11:04) Citation IconCite this Report


Twenty years of increased heat flow; crater ice melts; fumarole temperatures increase; larger plumes

University of Alaska geologists have documented a major long-term increase in heat flux at Mt. Wrangell, an andesitic shield volcano with a summit caldera 6 km long, 4 km wide, and 1 km deep. Heat flux from a crater on the N side of the summit caldera rim has increased by an order of magnitude since the great earthquake of 1964 (magnitude 8.3) centered ~250 km to the SW. Annual aerial photogrammetric surveys and digital cross sections demonstrate that since 1965 about 85% of the 4.4 x 107 m3 of ice in the north crater (figure 1) has melted; all melting at that altitude is caused by volcanic heat. Fumaroles remained at the boiling point (86°C at 600 mb pressure) from 1961 through the late 1970's, but some superheating may have begun by 1980, and in 1982 superheating was evident as vapor rose 1 m above the vents before condensing. In 1985, a temperature of l92°C was measured at the edge of one fumarole. The fumarole gases were dominantly water, but the SO2 content of the dry fraction was 28% in 1982 and 35% in 1985; most of the remaining gas was CO2 (gases were collected by Roman Motyka and Matthew Sturm, 1982, Matthew Sturm and Daniel Solie, 1985; analyses by W. Evans, USGS, and Roman Motyka).

Figure (see Caption) Figure 1. E-W cross-section of Wrangell's N crater, showing changes in the ice volume of the crater between 1957 and 1983; after Benson and Motyka (1978) and Benson and others (1984).

During April 1986, nearby residents reported occasional plumes rising as much as 1 km above the summit, with several observations of large plumes the last week of the month. On 30 April, the plume was estimated to be 1 km high and 300 m wide. Geologists plan overflights to monitor the activity.

References. Benson, C., and Follett, A., 1986, Application of photogrammetry to the study of volcano-glacier interactions on Mt. Wrangell, Alaska: Photogrammetric Engineering and Remote Sensing, v. 52, no. 6, p. 813-827.

Benson, C., and Motyka, R., 1978, Glacier-volcano interactions on Mt. Wrangell, Alaska: Annual Report, Geophysical Institute, University of Alaska, 1977-78, p. 1-25.

Benson, C., Sturm, M., and others, 1984, Glacier-volcano interactions, Mt. Wrangell, Alaska: Annual Report, Geophysical Institute, University of Alaska, 1983-84, p. 102-104.

Information Contacts: Carl S. Benson, Geophysical Institute, Univ of Alaska, Fairbanks; Roman Motyka, Alaska Dept of Natural Resources, Juneau.

The Global Volcanism Program has no Weekly Reports available for Wrangell.

Bulletin Reports - Index


Reports are organized chronologically and indexed below by Month/Year (Publication Volume:Number), and include a one-line summary. Click on the index link or scroll down to read the reports.

04/1986 (SEAN 11:04) Twenty years of increased heat flow; crater ice melts; fumarole temperatures increase; larger plumes




Information is preliminary and subject to change. All times are local (unless otherwise noted)


April 1986 (SEAN 11:04) Citation IconCite this Report


Twenty years of increased heat flow; crater ice melts; fumarole temperatures increase; larger plumes

University of Alaska geologists have documented a major long-term increase in heat flux at Mt. Wrangell, an andesitic shield volcano with a summit caldera 6 km long, 4 km wide, and 1 km deep. Heat flux from a crater on the N side of the summit caldera rim has increased by an order of magnitude since the great earthquake of 1964 (magnitude 8.3) centered ~250 km to the SW. Annual aerial photogrammetric surveys and digital cross sections demonstrate that since 1965 about 85% of the 4.4 x 107 m3 of ice in the north crater (figure 1) has melted; all melting at that altitude is caused by volcanic heat. Fumaroles remained at the boiling point (86°C at 600 mb pressure) from 1961 through the late 1970's, but some superheating may have begun by 1980, and in 1982 superheating was evident as vapor rose 1 m above the vents before condensing. In 1985, a temperature of l92°C was measured at the edge of one fumarole. The fumarole gases were dominantly water, but the SO2 content of the dry fraction was 28% in 1982 and 35% in 1985; most of the remaining gas was CO2 (gases were collected by Roman Motyka and Matthew Sturm, 1982, Matthew Sturm and Daniel Solie, 1985; analyses by W. Evans, USGS, and Roman Motyka).

Figure (see Caption) Figure 1. E-W cross-section of Wrangell's N crater, showing changes in the ice volume of the crater between 1957 and 1983; after Benson and Motyka (1978) and Benson and others (1984).

During April 1986, nearby residents reported occasional plumes rising as much as 1 km above the summit, with several observations of large plumes the last week of the month. On 30 April, the plume was estimated to be 1 km high and 300 m wide. Geologists plan overflights to monitor the activity.

References. Benson, C., and Follett, A., 1986, Application of photogrammetry to the study of volcano-glacier interactions on Mt. Wrangell, Alaska: Photogrammetric Engineering and Remote Sensing, v. 52, no. 6, p. 813-827.

Benson, C., and Motyka, R., 1978, Glacier-volcano interactions on Mt. Wrangell, Alaska: Annual Report, Geophysical Institute, University of Alaska, 1977-78, p. 1-25.

Benson, C., Sturm, M., and others, 1984, Glacier-volcano interactions, Mt. Wrangell, Alaska: Annual Report, Geophysical Institute, University of Alaska, 1983-84, p. 102-104.

Information Contacts: Carl S. Benson, Geophysical Institute, Univ of Alaska, Fairbanks; Roman Motyka, Alaska Dept of Natural Resources, Juneau.

Eruptive History


Summary of Holocene eruption dates and Volcanic Explosivity Indices (VEI).


Start Date Stop Date Eruption Certainty VEI Evidence Activity Area or Unit
2002 Aug 1 2002 Aug 2 Confirmed 1 Historical Observations
1999 May 14 1999 May 14 Confirmed 1 Historical Observations
1969 Aug Unknown Confirmed 1 Historical Observations West Crater
[ 1930 Jun 30 ] [ Unknown ] Uncertain    
[ 1921 Jul 3 ] [ 1921 Jul 3 ] Uncertain     North flank?
1911 Apr 14 1912 Sep 14 (?) Confirmed 1 Historical Observations
[ 1907 Apr 1 (in or before) ] [ Unknown ] Uncertain    
1902 Jul 15 ± 45 days Unknown Confirmed 2 Historical Observations West Crater
1900 Jun (in or before) Unknown Confirmed 2 Historical Observations
1899 Sep 3 Unknown Confirmed 2 Historical Observations
[ 1884 Oct 26 ] [ 1885 Feb 4 ] Uncertain 2  
[ 1819 ] [ Unknown ] Uncertain 2  
[ 1784 Jul ] [ Unknown ] Uncertain 2  
0190 ± 200 years Unknown Confirmed 4 Radiocarbon (uncorrected)

This compilation of synonyms and subsidiary features may not be comprehensive. Features are organized into four major categories: Cones, Craters, Domes, and Thermal Features. Synonyms of features appear indented below the primary name. In some cases additional feature type, elevation, or location details are provided.

Photo Gallery


This view, across the Copper River to the SE, shows 4949-m-high Mount Sanford (left) and 4317-m-high Mount Wrangell (right), two massive andesitic shield volcanoes. The dissected Sanford shield volcano has a broad, bulbous top that is surrounded by steep-walled glacial cirques. Most of the volcano formed in the Pleistocene, but part of the summit region may be of Holocene age. Eruptive activity at the younger, less-dissected Wrangell volcano has continued into historical time.

Photo by Donald Richter (Alaska Volcano Observatory, U.S. Geological Survey).
See title for photo information.
Mount Wrangell, a 4317-m-high andesitic shield volcano on the right skyline, is the only one in the Wrangell volcanic field to have had documented historical activity. Two large calderas truncate the summit; the inner ice-filled caldera contains 3 craters. Minor, possibly phreatic eruptions have occurred during the 20th century. At left is rounded Mount Zanetti, a 3965-m-tall flank cone; the sharp-topped peak at the extreme left of this view from the SW is a flank cone of the neighboring Pleistocene Mount Drum volcano.

Photo by B. Cella (National Park Service).
See title for photo information.
An aerial view shows a portion of the 4 x 6 km, ice-filled summit caldera of Mount Wrangell, a 4317-m-high andesitic shield volcano. It is the only volcano in the Wrangell volcanic field to have had documented historical eruptions. These have consisted of minor, possibly phreatic eruptions. Fumarolic activity (right center) continues from one of three cinder cones on the rim of the caldera.

Photo by Chris Nye (Alaska Division of Geological and Geophysical Surveys, Alaska Volcano Observatory).
See title for photo information.
Alaska's Mount Wrangell is one of the most voluminous andesitic shield volcanoes in the world and is more than three times the volume of Mount Rainier. The massive volcano has a diameter of 30 km at 2000 m elevation and a volume of about 900 cu km. Eruption of unusually fluid andesitic lavas at high eruption rates produced long lava flows that contributed to its low-angle shield morphology. The small snow-covered peak on the left is Mount Zanetti, a flank vent about the same volume as St. Helens. Wrangell is seen here from Glenallen, 80 km to the west.

Photo by Chris Nye (Alaska Division of Geological and Geophysical Surveys).
See title for photo information.
U. S. Geological Survey geologist W. C. Mendenhall viewed smoke and vapor columns and ash-covered snow during a 1902 expedition in the Mount Wrangell area. A photograph shows a smoke (and ash?) column rising above the summit crater and was probably taken during the summer of 1902. Ash darkens the snow over a wide area of the southern slopes of the volcano. The small cone on the far left horizon is Mount Zanetti.

Photo by W. C. Mendenhall, 1902 (U. S. Geological Survey).
See title for photo information.

Smithsonian Sample Collections Database


The following 4 samples associated with this volcano can be found in the Smithsonian's NMNH Department of Mineral Sciences collections. Catalog number links will open a window with more information.

Catalog Number Sample Description
NMNH 117233-30 Volcanic ash
NMNH 117233-37 Pumice
NMNH 117457-2 Rhyolite with obsidian and biotite
NMNH 117457-3 Obsidian

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