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  • United States
  • Alaska
  • Stratovolcano
  • 1830 CE
  • Country
  • Volcanic Region
  • Primary Volcano Type
  • Last Known Eruption
  • 54.65°N
  • 164.43°W

  • 1112 m
    3647 ft

  • 311350
  • Latitude
  • Longitude

  • Summit

  • Volcano

The Global Volcanism Program has no activity reports for Fisher.

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

The Global Volcanism Program has no Bulletin Reports available for Fisher.

Basic Data

Volcano Number

Last Known Eruption



1830 CE

1112 m / 3647 ft


Volcano Types

Lava dome(s)

Rock Types

Andesite / Basaltic Andesite
Basalt / Picro-Basalt
Trachyte / Trachyandesite

Tectonic Setting

Subduction zone
Continental crust (> 25 km)


Within 5 km
Within 10 km
Within 30 km
Within 100 km

Geological Summary

The 11 x 18 km Fisher caldera on western Unimak Island NE of Westdahl volcano is one of the largest calderas in the Aleutian arc. The caldera, which is elongated in a NE direction, formed around 9400 years ago, accompanied by emission of large-volume, mobile pyroclastic flows that reached the Bering Sea and the Pacific Ocean. Two satellitic cones are located below the north rim, NE of its 1112-m high point at Eickelberg Peak, which rises more than 900 m above three lakes on the caldera floor, one of which drains through a notch in the southern caldera rim. A large composite cone, Mount Finch, is found at the center of the caldera, which also contains a small breached cinder cone. Historical eruptions have occurred in the 18th and 19th centuries. Low-temperature fumaroles are located at the western flank of Mount Finch, and Turquoise Lake, at the base of the cone, emits hydrogen sulfide gas.


The following references have all been used during the compilation of data for this volcano, it is not a comprehensive bibliography.

Bindeman I A, Fournelle J H, Valley J W, 2001. Low-delta 18O tephra from a compositionally zoned magma body: Fisher caldera, Unimak Island, Aleutians. J Volc Geotherm Res, 111: 35-53.

Coats R R, 1950. Volcanic activity in the Aleutian Arc. U S Geol Surv Bull, 974-B: 35-47.

Fournelle J H, 1988. The geology and petrology of Shishaldin volcano, Unimak Island, Aleutian arc, Alaska. Unpublished PhD thesis, John Hopkins Univ, 507 p.

Gardner J E, Burgisser A, Stelling P, 2007. Eruption and deposition of the Fisher Tuff (Alaska): evidence for the evolution of pyroclastic flows. J Geol, 115: 417-435.

IAVCEI, 1973-80. Post-Miocene Volcanoes of the World. IAVCEI Data Sheets, Rome: Internatl Assoc Volc Chemistry Earth's Interior..

Miller T P, McGimsey R G, Richter D H, Riehle J R, Nye C J, Yount M E, Dumoulin J A, 1998. Catalogue of the historically active volcanoes of Alaska. U S Geol Surv Open-File Rpt, 98-582: 1-104.

Miller T P, Smith R L, 1977. Spectacular mobility of ash flows around Aniakchak and Fisher Calderas, Alaska. Geology, 5: 173-176.

Motyka R J, Liss S A, Nye C J, Moorman M A, 1993. Geothermal resources of the Aleutian arc. Alaska Div Geol Geophys Surv, Prof Rpt, no 114, 17 p and 4 map sheets.

Myers J D, 1994. The Geology, Geochemistry and Petrology of the recent Magmatic Phase of the Central and Western Aleutian Arc. Unpublished manuscript, unpaginated.

Smith R L, Shaw H R, 1975. Igneous-related geothermal systems. U S Geol Surv Circ, 726: 58-83.

Smith R L, Shaw H R, Luedke R G, Russell S L, 1978. Comprehensive tables giving physical data and thermal energy estimates for young igneous systems of the United States. U S Geol Surv Open-File Rpt, 78-925: 1-25.

Stelling P, Gardner J E, Beget J, 2005. Eruptive history of Fisher caldera, Alaska, USA. J Volc Geotherm Res, 139: 163-183.

Eruptive History

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

Start Date Stop Date Eruption Certainty VEI Evidence Activity Area or Unit
1830 Aug Unknown Confirmed 2 Historical Observations Mount Finch
1826 Oct 11 1827 Jan (?) Confirmed 3 Historical Observations Mount Finch
1795 (in or before) Unknown Confirmed   Historical Observations
0400 ± 50 years Unknown Confirmed   Radiocarbon (uncorrected) Turquoise cone
3170 BCE ± 75 years Unknown Confirmed 5 Radiocarbon (uncorrected) Turquoise cone
7420 BCE ± 200 years Unknown Confirmed 6 Radiocarbon (uncorrected) NE and SW parts of Fisher caldera

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.


Metrogoon Lake


Feature Name Feature Type Elevation Latitude Longitude
Eastern Mound Stratovolcano
Eickelberg Peak Stratovolcano 1094 m
Finch, Mount Stratovolcano 477 m 54° 40' 0" N 164° 22' 0" W
Neptune Cone Stratovolcano
Nick's Cone Cone
Turquoise Cone Stratovolcano


Feature Name Feature Type Elevation Latitude Longitude
Pyro Hill Maar

Photo Gallery

This 1974 view shows part of the interior of Fisher caldera on Unimak Island in the eastern Aleutian Islands. Fisher is an 11 x 18 km caldera that formed about 9100 years ago during the eruption of compositionally zoned ash flows that overtopped topographic barriers more than 500 m in elevation. The caldera contains two large lakes and a smaller lake that drains through a notch in the south caldera rim. There has been one poorly documented historical eruption from Fisher in 1826.

Photo by Tom Miller, 1974 (U.S. Geological Survey).

Smithsonian Sample Collections Database

The following 11 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 117233-174 Pumice
NMNH 117233-175 Pumice
NMNH 117233-176 Pumice
NMNH 117233-177 Bomb
NMNH 117233-178 Tuff
NMNH 117233-179 Pumice
NMNH 117233-181 Pumice
NMNH 117233-182 Glass
NMNH 117233-185 Pumice
NMNH 117233-186 Obsidian
NMNH 117233-187 Obsidian

Affiliated Sites

Large Eruptions of Fisher Information about large Quaternary eruptions (VEI >= 4) is cataloged in the Large Magnitude Explosive Volcanic Eruptions (LaMEVE) database of the Volcano Global Risk Identification and Analysis Project (VOGRIPA).
WOVOdat WOVOdat is a database of volcanic unrest; instrumentally and visually recorded changes in seismicity, ground deformation, gas emission, and other parameters from their normal baselines. It is sponsored by the World Organization of Volcano Observatories (WOVO) and presently hosted at the Earth Observatory of Singapore.
EarthChem EarthChem develops and maintains databases, software, and services that support the preservation, discovery, access and analysis of geochemical data, and facilitate their integration with the broad array of other available earth science parameters. EarthChem is operated by a joint team of disciplinary scientists, data scientists, data managers and information technology developers who are part of the NSF-funded data facility Integrated Earth Data Applications (IEDA). IEDA is a collaborative effort of EarthChem and the Marine Geoscience Data System (MGDS).
MODVOLC - HIGP MODIS Thermal Alert System Using infrared satellite Moderate Resolution Imaging Spectroradiometer (MODIS) data, scientists at the Hawai'i Institute of Geophysics and Planetology, University of Hawai'i, developed an automated system called MODVOLC to map thermal hot-spots in near real time. For each MODIS image, the algorithm automatically scans each 1 km pixel within it to check for high-temperature hot-spots. When one is found the date, time, location, and intensity are recorded. MODIS looks at every square km of the Earth every 48 hours, once during the day and once during the night, and the presence of two MODIS sensors in space allows at least four hot-spot observations every two days. Each day updated global maps are compiled to display the locations of all hot spots detected in the previous 24 hours. There is a drop-down list with volcano names which allow users to 'zoom-in' and examine the distribution of hot-spots at a variety of spatial scales.
MIROVA Middle InfraRed Observation of Volcanic Activity (MIROVA) is a near real time volcanic hot-spot detection system based on the analysis of MODIS (Moderate Resolution Imaging Spectroradiometer) data. In particular, MIROVA uses the Middle InfraRed Radiation (MIR), measured over target volcanoes, in order to detect, locate and measure the heat radiation sourced from volcanic activity.