Fisher


Facts


  • Official Name: Fisher Caldera
  • Seismically Monitored: No
  • Color Code: UNASSIGNED
  • Alert Level: UNASSIGNED
  • Elevation: 1112m (3648ft)
  • Latitude: 54.6692
  • Longitude: -164.3524
  • Smithsonian VNum: 311350
  • Nearby Towns:
    • False Pass 40 mi (64 km) NE
    • Pauloff Harbor 68 mi (109 km) SE
    • Akutan 68 mi (109 km) SW
    • Cold Bay 74 mi (119 km) NE
    • King Cove 86 mi (138 km) NE
  • Subfeatures:
    • Eickelberg Peak (Cone 8)
    • Finch, Mt
    • Nick's cone
    • Pyro Hill
    • Turquoise cone
    • Neptune

Description

From Miller and others (1998): "Fisher caldera is 11 km wide by 18 km long, and has a maximum internal relief of 929 m. It is one of at least three volcanoes on Unimak Island that have been active in historical time.
"The caldera is remarkable in size - one of the largest calderas in the Aleutian arc - and for the mobility of the ash flows that resulted from the caldera-forming eruption about 9100 years ago (Miller and Smith, 1977; 1987). The ash flows reached the Pacific Ocean 8 km to the southeast, and swept part way up the slopes of stratovolcanoes to the east and southwest. To the north, ash flows crossed 15 km of lowland to reach the Tugamak Range, surmounted drainage divides as much as 400 m above the lowland surface in the range, and continued northward an additional 8 km to the Bering Sea coastline. Miller and Smith (1977) inferred that the ash flows had unusually high velocities to cross such topographic barriers and suggested that the high velocities resulted by ash fall-back from a high eruption column.
"Fisher caldera was the location of a large andesitic stratovolcano that was largely destroyed during caldera formation. Very little study has been done on the caldera itself. Post-caldera activity of Fisher caldera appears to consist of dome emplacement and eruption of lava flows and associated pyroclastic material, some of which may be historical in age (Miller and Smith, 1977)."

Name Origin

Fisher Caldera was named for Bernard Fisher of the U.S. Geological Survey, who lost his life in Umnak Pass while investigating the volcanic geology of the Aleutian Islands (U.S. Geographic Names Informaion System, accessed January 14, 2009.


Current Activity

February 7, 2024, 10:42 am

The Alaska Volcano Observatory (AVO) has experienced the failure of seismic monitoring equipment at Fisher Volcano and the remaining instrumentation is insufficient to establish that the volcano is at a typical background level. It is not possible to repair this equipment until next summer's field season. As a result, AVO is unable to (1) assess whether this volcano may be building towards an eruption and (2) quickly confirm or dismiss reports of activity.

The Aviation Color Code and Volcano Alert Level are changed to UNASSIGNED/UNASSIGNED because this volcano is no longer seismically monitored at adequate levels. As at other volcanoes without real-time seismic networks, AVO will continue to use satellite data, regional seismic, infrasound, and lightning networks, and reports from pilots and ground observers to detect signs of eruptive activity.

Color Code Timeline

ASHFALL AND ASH CLOUD FORECASTS: MODEL OUTPUT

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