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Mount Iō

Kikai

Caldera · Japan · 704m

Kikai is a mostly submerged 19-km-wide caldera S of Kyushu that was the source of one of the world's largest Holocene eruptions about 6,300 years ago. Pyroclastic flows traveled across the sea for a total distance of 100 km and devastated southern and central Kyushu. This view from near the summit of the post-caldera Iwodake cone shows the W rim of Kikai caldera forming the peninsula (upper left) behind the Inamuradake scoria cone.
Kikai is a mostly submerged 19-km-wide caldera S of Kyushu that was the source of one of the world's largest Holocene eruptions about 6,300 years ago. Pyroclastic flows traveled across the sea for a total distance of 100 km and devastated southern and central Kyushu. This view from near the summit of the post-caldera Iwodake cone shows the W rim of Kikai caldera forming the peninsula (upper left) behind the Inamuradake scoria cone. · Photo: Photo by Yasuo Miyabuchi, 1996 (Forestry and Forest Products Research Institute, Kyushu). · Wikimedia Commons
Type
Caldera
Country
Japan
Region
Western Pacific Volcanic Regions / Ryukyu Volcanic Arc
Elevation
704m
Coordinates
30.793, 130.305
Last eruption
2025
Tectonic setting
Subduction zone / Oceanic crust (< 15 km)
Landform
Caldera
Major rock type
Rhyolite
Geological summary

Multiple eruption centers have exhibited recent activity at Kikai, a mostly submerged, 19-km-wide caldera near the northern end of the Ryukyu Islands south of Kyushu. It was the source of one of the world's largest Holocene eruptions about 6,300 years ago when rhyolitic pyroclastic flows traveled across the sea for a total distance of 100 km to southern Kyushu, and ashfall reached the northern Japanese island of Hokkaido. The eruption devastated southern and central Kyushu, which remained uninhabited for several centuries. Post-caldera eruptions formed Iodake (or Iwo-dake) lava dome and Inamuradake scoria cone, as well as submarine lava domes. Recorded eruptions have occurred at or near Satsuma-Iojima (also known as Tokara-Iojima), a small 3 x 6 km island forming part of the NW caldera rim. Showa-Iojima lava dome (also known as Iojima-Shinto), a small island 2 km E of Satsuma-Iojima, was formed during submarine eruptions in 1934 and 1935. Mild-to-moderate explosive eruptions have occurred during the past few decades from Iodake, a rhyolitic lava dome at the eastern end of Satsuma-Iojima.

From Wikipedia

Mount Iō, also known as Mount Iwo, is an active rhyolitic lava dome on Iōjima in Kagoshima Prefecture, Japan. It sits within the borders of the town of Mishima.

Wikipedia · CC BY-SA · Read full article →

Eruption history

Summary (VEI over time)
Click a bar to see individual eruptions
4350 BCE~4137 BCE · 1 eruptions · max VEI 73287 BCE~3075 BCE · 1 eruptions · max VEI ?2650 BCE~2437 BCE · 1 eruptions · max VEI ?2012 BCE~1800 BCE · 1 eruptions · max VEI ?1162 BCE~950 BCE · 1 eruptions · max VEI 2312 BCE~100 BCE · 1 eruptions · max VEI ?325~538 · 1 eruptions · max VEI 3750~963 · 2 eruptions · max VEI 3963~1175 · 2 eruptions · max VEI ?1175~1388 · 1 eruptions · max VEI ?1388~1600 · 1 eruptions · max VEI ?1813~2025 · 17 eruptions · max VEI 24350 BCE2862 BCE1162 BCE3251813

Detailed timeline

  1. 2025VEI 1Observed
    2025-12-29 – 2025-12-29
    Iodake Crater
  2. 2024VEI 1Observed
    2024-09-01 – 2024-09-03
    Satsuma Iwo-jima (Iodake Crater)
  3. 2023VEI ?Observed
    2023-03-27 – 2023-07-31
  4. 2020VEI 1Observed
    2020-04-29 – 2020-04-29
  5. 2020VEI 1Observed
    2020-10-06 – 2020-10-06
  6. 2019VEI 2Observed
    2019-11-02 – 2019-11-02
  7. 2013VEI 1Observed
    2013-06-04 – 2013-06-04
    Iodake
  8. 2004VEI 2Observed
    2004-03-05 – 2004-10-16
    Iwo-dake
  9. 2003VEI 2Observed
    2003-02-16 – 2003-10-16
    Iwo-dake
  10. 2002VEI 2Observed
    2002-05-11 – 2002-07-16
    Iwo-dake
  11. 2000VEI 2Observed
    2000-01-16 – 2000-03-16
    Iwo-dake
  12. 2000VEI 1Observed
    2000-10-16 – 2001-12-16
    Iwo-dake
  13. 1998VEI 2Observed
    1998-04-25 – 1999-08-16
    Iwo-dake
  14. 1997VEI 1Observed
    1997-07-02 – Ongoing
    Iwo-dake
  15. 1988VEI 1Observed
    1988-01-18 – 1988-01-18
    Iwo-dake
  16. 1934VEI 2Observed
    1934-09-19 – 1935-08
    2 km east of Tokara-Iwo-Jima
  17. 1914VEI ?Geological estimate
    1914-02-13 – Ongoing
    Tokara-Iwo-jima
  18. 1430 (±75 yrs)VEI ?Geological estimate
    1430 – Ongoing
    Iwo-dake
  19. 1340 (±30 yrs)VEI ?Geological estimate
    1340 – Ongoing
    Iwo-dake
  20. 1030 (±40 yrs)VEI ?Geological estimate
    1030 – Ongoing
    Iwo-dake
  21. 1010 (±40 yrs)VEI ?Geological estimate
    1010 – Ongoing
    Iwo-dake
  22. 830 (±40 yrs)VEI ?Geological estimate
    830 – Ongoing
    Iwo-dake
  23. 750VEI 3Geological estimate
    750 – Ongoing
    Iwo-dake
  24. 390 (±100 yrs)VEI 3Geological estimate
    390 – Ongoing
    Iwo-dake
  25. 280 BCE (±75 yrs)VEI ?Geological estimate
    BCE 280 – Ongoing
    Iwo-dake
  26. 1090 BCE (±100 yrs)VEI 2Geological estimate
    BCE 1090 – Ongoing
    Inamura-dake
  27. 1830 BCE (±75 yrs)VEI ?Geological estimate
    BCE 1830 – Ongoing
    Inamura-dake
  28. 2450 BCE (±840 yrs)VEI ?Geological estimate
    BCE 2450 – Ongoing
    Old Iwo-dake
  29. 3250 BCE (±75 yrs)VEI ?Geological estimate
    BCE 3250 – Ongoing
    Old Iwo-dake
  30. 4350 BCEVEI 7Geological estimate
    BCE 4350 – Ongoing
    Kikai caldera

External links

⚠ For reference only. Not for emergency response.