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Japan · Caldera

Iwo Jima

Ioto

Type
Caldera
Elevation
172m
Last eruption
2025
Iwo Jima
Photo: ASTER volcano archive JPL/NASA · Public domain · Wikimedia Commons
Type
Caldera
Country
Japan
Region
Northwestern Pacific / Ogasawara Volcanic Arc
Elevation
172m
Coordinates
24.750, 141.289
Last eruption
2025
Tectonic setting
Subduction zone / Crustal thickness unknown
Landform
Caldera
Major rock type
Trachyandesite / Basaltic trachyandesite
Geological summary

Ioto, also known as Ogasawara-Iojima to distinguish it from several other "Sulfur Island" volcanoes, lies within a 9-km-wide submarine caldera.The triangular, low-elevation, 8-km-long island narrows toward its SW tip and has produced trachyandesitic and trachytic rocks that are more alkalic than those of other volcanoes in the Ogasawara Volcanic Arc. The island has undergone uplift for at least the past 700 years, accompanying resurgent doming of the caldera; a shoreline landed upon by Captain Cook's surveying crew in 1779 is now 40 m above sea level. The Motoyama plateau on the NE half of the island consists of submarine tuffs overlain by coral deposits and forms the island's high point. Many fumaroles are oriented along a NE-SW zone cutting through Motoyama. Numerous recorded phreatic eruptions, many from vents on the W and NW sides of the island, have accompanied the uplift.

Eruption history

33 recordedGlossary
Summary (VEI over time)
Click a bar to see individual eruptions · Use arrow keys to move between bars, Enter to open
850 BCE~658 BCE · 1 eruptions · max VEI ?1833~2025 · 32 eruptions · max VEI 1850 BCE83 BCE49212581833

Detailed timeline

  1. 2025VEI 1Observed
    2025-09-01 – 2025-09-02
  2. 2023VEI 1Observed
    2023-10-18 – 2024-03-16
  3. 2022VEI 1Observed
    2022-07-11 – 2022-12-11
    Off SE coast
  4. 2021VEI 1Observed
    2021-08-12 – 2021-11-24
    Off SE coast
  5. 2020VEI 1Observed
    2020-12-28 – 2021-04-05
    Asodai Sinkhole
  6. 2018VEI 1Observed
    2018-09-08 – 2018-09-14
    Off the S coast
  7. 2016VEI 1Observed
    2016-08-31 – 2016-09-01
    Asodai Sinkhole
  8. 2015VEI 1Observed
    2015-08-07 – 2015-08-07
    Kianohana Beach (N part of the island)
  9. 2013VEI 0Observed
    2013-08-21 – 2013-08-30
    Off the NE coast
  10. 2012VEI 1Observed
    2012-12-01 – 2013-04-11
    Asodai
  11. 2012VEI 1Observed
    2012-02-10 – 2012-07-09
    Asodai
  12. 2010VEI 1Observed
    2010-06-19 – 2010-06-19
  13. 2004VEI 1Method not stated
    2004-06-06 – 2004-06-08
    Asodai area
  14. 2001VEI 1Observed
    2001-09-21 – 2001-10-23
    Off SE coast and Idogahama (NW coast)
  15. 1999VEI 1Observed
    1999-09-10 – 1999-09-10
    Asodai area
  16. 1994VEI 1Observed
    1994-08-22 – 1994-08-22
    NE side
  17. 1993VEI 1Method not stated
    1993-10-27 – 1993-11-16
    Asodai area and NE of Iwo-jima
  18. 1982VEI 1Observed
    1982-03-09 – 1982-03-10
    NW side (Idogahama beach)
  19. 1982VEI 1Observed
    1982-11-28 – 1982-12-16
    West side (Asodai)
  20. 1980VEI 1Observed
    1980-03-13 – 1980-03-13
    Kitanohara
  21. 1978VEI 1Observed
    1978-12-11 – 1978-12-11
    West side (Asodai)
  22. 1976VEI 1Observed
    1976-01-16 – end unknown
    West side (Asodai)
  23. 1974VEI 0Method not stated
    1974-01-16 – 1974-02-02
    NW of Iwo-jima (Kaiseinishinoba)
  24. 1969VEI 1Observed
    1969-01-12 – 1969-01-21
    West side (Asodai)
  25. 1969VEI 1Observed
    1969-12-01 – 1969-12-01
  26. 1967VEI 1Observed
    1967-12-23 – 1967-12-23
    West side (Asodai)
  27. 1957VEI 1Observed
    1957-03-28 – 1957-03-28
    Chidoriga-hara
  28. 1944VEI 1Observed
    1944-12-16 – end unknown
    North and west sides near the coast
  29. 1935VEI 1Observed
    1935-07-02 – end unknown
    SW side at Chidoriga-hara
  30. 1930VEI 1Observed
    1930-07-02 – end unknown
    NW side near the coast
  31. 1922VEI 1Observed
    1922-07-16 – end unknown
    West side (Asodai)
  32. 1889VEI 1Observed
    1889-12-31 – end unknown
    Chidoriga-ana
  33. 850 BCE (±50 yrs)VEI ?Geological estimate
    850 BCE – end unknown
    Motoyama

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External links

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