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Mount Chōkai

Chokaisan

Stratovolcano · Japan · 2236m

Chokaisan is the largest of the NE Honshu volcanoes, seen here from the NE. The volcano is comprised of two main overlapping edifices, the younger eastern area contains the large collapse scarp that was the source of the Kisakata debris avalanche, seen here opening to the N. Smaller cones later filled much of the area near the rear scarp.
Chokaisan is the largest of the NE Honshu volcanoes, seen here from the NE. The volcano is comprised of two main overlapping edifices, the younger eastern area contains the large collapse scarp that was the source of the Kisakata debris avalanche, seen here opening to the N. Smaller cones later filled much of the area near the rear scarp. · Photo: Photo courtesy Ichio Moriya (Kanazawa University). · Wikimedia Commons
Type
Stratovolcano
Country
Japan
Region
Northwestern Pacific Volcanic Regions / Northeast Japan Volcanic Arc
Elevation
2236m
Coordinates
39.099, 140.049
Last eruption
1974
Tectonic setting
Subduction zone / Continental crust (> 25 km)
Landform
Composite
Major rock type
Andesite / Basaltic Andesite
Geological summary

Massive Chokaisan volcano is composed of two overlapping stratovolcanoes with a conical profile that inspired the local names of Akita-Fuji or Dewa-Fuji. The summit of the gently sloping western edifice (Nishi-Chokaisan) is cut by a large scarp open to the south that contains lava domes. The younger eastern volcano (Higashi-Chokaisan) began forming about 20,000 years ago, and also has a large scarp, breached to the north. During an eruption about 2,600 years ago it was the source of the voluminous Kisakata debris avalanche, which reached the Pacific coast. Two post-caldera lava domes have been constructed at the upper SE end of the caldera. Intermittent reports of eruptions date back to the 6th century CE.

From Wikipedia

Mount Chōkai is an active volcano located on the border of Akita and Yamagata in the Tōhoku region of Japan, and is 2,236 m (7,336 ft) tall. Because of its (roughly) symmetrical shape and massive size, it is also variously known as Dewa Fuji (出羽富士), Akita Fuji (秋田富士) or Shōnai Fuji (庄内富士) depending on the location of the viewer. In addition to being one of the 100 Famous Landscapes of Japan, it is also included as one of the 100 famous mountains in Japan, and famous 100 Geographical Features of Japan. It is surrounded by Chōkai Quasi-National Park. It is also a National Historic Site of Japan, and is regarded as a sacred mountain by followers of the Shugendō branch of Shinto which has the shrine Chōkaisan Ōmonoimi Shrine there and is popular with hikers.

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Eruption history

Summary (VEI over time)
Click a bar to see individual eruptions
1050 BCE~861 BCE · 1 eruptions · max VEI 0672 BCE~483 BCE · 1 eruptions · max VEI ?483 BCE~294 BCE · 1 eruptions · max VEI ?462~651 · 3 eruptions · max VEI ?651~840 · 6 eruptions · max VEI ?840~1029 · 8 eruptions · max VEI 31407~1596 · 2 eruptions · max VEI ?1596~1785 · 5 eruptions · max VEI 21785~1974 · 4 eruptions · max VEI 21050 BCE294 BCE46210291785

Detailed timeline

  1. 1974VEI 1Observed
    1974-03-01 – 1974-04-30
    E side of Shinzan, W of Kojin-yama
  2. 1834VEI 2Observed
    1834-07-09 – 1834-07
  3. 1821VEI 2Observed
    1821-05-23 – Ongoing
    Near Shinzan and Shichiko-zan
  4. 1800VEI 2Observed
    1800-12 – 1804-07
    Shinzan (foot of Kojin-yama)
  5. 1764VEI 2Geological estimate
    1764 – Ongoing
  6. 1740VEI 2Observed
    1740-06 – 1747
    Small crater at foot of Kojin-yama
  7. 1738VEI 2Geological estimate
    1738-12-31 – Ongoing
  8. 1735VEI 2Geological estimate
    1735 – Ongoing
  9. 1659VEI ?Observed
    1659-04 – 1663
  10. 1560VEI ?Geological estimate
    1560 – Ongoing
  11. 1477VEI ?Geological estimate
    1477 – Ongoing
  12. 999VEI ?Geological estimate
    999 – Ongoing
  13. 948VEI ?Geological estimate
    948-12-31 – Ongoing
  14. 939VEI ?Observed
    939-05-15 – Ongoing
  15. 884VEI ?Geological estimate
    884-07-26 – 884-08
  16. 871VEI 2Observed
    871-05-05 – Ongoing
  17. 861VEI 3Geological estimate
    861-05 – Ongoing
  18. 857VEI ?Geological estimate
    857-05 – Ongoing
  19. 856VEI ?Geological estimate
    856 – Ongoing
  20. 839VEI ?Geological estimate
    839-10-14 – Ongoing
  21. 830VEI ?Observed
    830-01 – Ongoing
  22. 817 (±7 yrs)VEI ?Observed
    817 – Ongoing
  23. 804VEI ?Geological estimate
    804 – 806
  24. 717VEI ?Geological estimate
    717-07 – Ongoing
  25. 711 (±3 yrs)VEI ?Observed
    711 – Ongoing
  26. 610 (±18 yrs)VEI ?Geological estimate
    610 – Ongoing
  27. 577VEI ?Geological estimate
    577-12-01 – 578-07-15
  28. 573VEI ?Geological estimate
    573-03 – Ongoing
  29. 450 BCEVEI ?Geological estimate
    BCE 450 – Ongoing
  30. 650 BCEVEI ?Geological estimate
    BCE 650 – Ongoing
    Higashi-Chokai
  31. 1050 BCEVEI 0Geological estimate
    BCE 1050 – Ongoing
    West flank (Saruana crater)

External links

⚠ For reference only. Not for emergency response.