Roundtop

Photo of this volcano
  • United States
  • Alaska
  • Stratovolcano
  • 7600 BCE
  • Country
  • Volcanic Region
  • Primary Volcano Type
  • Last Known Eruption
  • 54.8°N
  • 163.589°W

  • 1871 m
    6137 ft

  • 311380
  • Latitude
  • Longitude

  • Summit
    Elevation

  • Volcano
    Number

The Global Volcanism Program has no activity reports for Roundtop.

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

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

Eruptive History


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


Start Date Stop Date Eruption Certainty VEI Evidence Activity Area or Unit
7600 BCE ± 500 years Unknown Confirmed 5 Tephrochronology

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


Three prominent volcanoes are constructed along an E-W line on the eastern half of Unimak Island. The aptly named Roundtop volcano in the lower foreground is glacially eroded and has had no historical eruptive activity. In the 1930s warm springs were found on its slopes. The recent discovery of Holocene pyroclastic-flow deposits and a group of lava domes south of Roundtop indicate it is still an active volcano. The glacially dissected Isanotski volcano and the beautifully symmetrical Shishaldin volcano are the prominent peaks behind Roundtop.

Photo by Clayton and Marcia Brown, 1986 (courtesy of John Reeder, Alaska Div. Geology Geophysical Surveys).
See title for photo information.
Three prominent stratovolcanoes are constructed along an E-W line on Unimak Island. Steaming Shishaldin, the highest of the three, rises to 2857 m in the foreground and is one of the most active volcanoes in the Aleutians. The dissected Isanotski volcano (right) has had reported eruptions of uncertain validity, and Roundtop volcano (center distance) has had Holocene eruptions, but no historical activity.

Photo by Clayton and Marcia Brown, 1987 (courtesy of John Reeder, Alaska Div. Geology & Geophysical Surveys).
See title for photo information.
The flat-topped, glacier-covered Roundtop volcano, rising to the west beyond buildings of the village of False Pass, is the easternmost and lowest of an E-W-trending line of volcanoes on Unimak Island. Roundtop has produced Holocene pyroclastic flows, and a group of lava domes was constructed south of the volcano. No historical eruptions are known from the 1871-m-high stratovolcano. In the 1930s warm springs were found on its slopes.

Photo by Game McGimsey, 1998 (Alaska Volcano Observatory, U.S. Geological Survey).
See title for photo information.

Smithsonian Sample Collections Database


There are no samples for Roundtop in the Smithsonian's NMNH Department of Mineral Sciences Rock and Ore collection.

Affiliated Sites