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United States · Stratovolcano

Semisopochnoi Island

Semisopochnoi

Type
Stratovolcano
Elevation
1221m
Last eruption
2023
Semisopochnoi Island
Photo: U.S. Navy · Public domain · Wikimedia Commons
Type
Stratovolcano
Country
United States
Region
North America / Aleutian Ridge Volcanic Arc
Elevation
1221m
Coordinates
51.930, 179.580
Last eruption
2023
Tectonic setting
Subduction zone / Intermediate crust (15-25 km)
Landform
Composite
Major rock type
Basalt / Picro-basalt

Geological summary

Semisopochnoi, the largest subaerial volcano of the western Aleutians, is 20 km wide at sea level and contains an 8-km-wide caldera.

Excerpt from the Global Volcanism Program, Smithsonian Institution · Read the full summary on GVP →

From Wikipedia

Semisopochnoi Island or Unyak Island is part of the Rat Islands group in the western Aleutian Islands of Alaska. The island is uninhabited and provides an important nesting area for maritime birds. The island is of volcanic origin, containing several volcanoes including Mount Young. It has a land area of 85.558 square miles, measuring 11 miles (18 km) in length and 12 miles (20 km) in width.

Wikipedia · CC BY-SA · Read full article →

Eruption history

10 recordedGlossary

Record summary

Confirmed eruptions
6
Uncertain eruptions
4
Span of confirmed record
1873 – 2023
Largest confirmed eruption
VEI 2 (2021, the most recent of 2)
Confirmed eruptions since 1900
5
Summary (VEI over time)
Click a bar to see individual eruptions · Use arrow keys to move between bars, Enter to open
1772~1797 · 3 eruptions · max VEI ?1822~1847 · 1 eruptions · max VEI ?1872~1897 · 1 eruptions · max VEI ?1971~1996 · 1 eruptions · max VEI 21996~2021 · 4 eruptions · max VEI 217721822189719461996

Detailed timeline

  1. 2021VEI 2Observed
    2021-02-02 – 2023-05-05
    North Cerberus
  2. 2019VEI 1Observed
    2019-07-16 – 2019-08-24
  3. 2019VEI 1Observed
    2019-12-07 – 2020-06-19
    North Cerberus
  4. 2018VEI 1Observed
    2018-09-08 – 2018-10-31
    North Cone of Mount Cerberus (Mount Young)
  5. 1987VEI 2Observed
    1987-04-13 – 1987-04-18
    Sugarloaf ?
  6. 1873VEI ?Observed
    1873-07-02 – end unknown
    Cerberus
  7. 1830VEI ?Method not stated
    1830-07-02 – end unknown
    Cerberus
  8. 1792VEI ?Method not stated
    1792 – end unknown
    Cerberus
  9. 1790VEI ?Method not stated
    1790 – end unknown
    Cerberus
  10. 1772VEI ?Method not stated
    1772 – end unknown
    Cerberus

Nearby volcanoes

External links

⚠ For reference only. Not for emergency response.