Chokai volcano

stratovolcanoes 2233 m / 7,326 ft
Honshu, Japan, 39.1°N / 140.05°E
Current status: normal or dormant (1 out of 5)
Chokai volcano
Chokai volcano

Chokai volcano (鳥海山 Chōkai-san) is the largest volcano of NE Honshu.
It is a massive stratovolcano with a broad conical profile which is why it is called locally Akita-Fuji or Dewa-Fuji. Its height measures from the WNW elongated 15x20 km base about 2000 m.
The volcano is located about 60 km west behind the main volcanic front of the Honshu arc and towers above the Japan Sea.
Chokai consists of 2 overlapping volcanoes, the western and older volcano Nishi-Chokai and the younger eastern volcano Higashi-Chokai, forming the 2 distinct peaks. Historic records of eruptions, mostly phreatic explosions, go back to the 6th century AD.

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Typical eruption style: phreatic explosions
Chokai volcano eruptions: March-April 1974: phreatic ash explosions and mud flows
1834: phreatic explosions and mud flows
1821: phreatic explosions
1800-04, 1764 (?), 1740-47, 1738±1 (?), 1735 (?), 1659-63, 1560 (?), 1477 (?), 999 AD (?), 948±1, 939, (915: no eruption, was from Towada volcano), 884 (?), 871, 861 (?), 857 (?), 856 (?), 839 (?), 830, 817 AD ± 7 years, 804-06, 717 (?), 711± 3 years, 610± 18 years (?), 577-78 (?), 573 (?), 450 BC, 650 BC, 1050 BC (?)

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Background

The older Nishi-Chokai volcano suffered flank collapse leaving a large horseshoe-shaped caldera open to the south. Lava domes grew on the caldera floor. A younger stratovolcano grew successively to the east, building Higashi-Chokai from about 20,000 years ago. This volcano, too, partly collapsed about 2600 years ago and left a caldera breached to the north. The collapse produced the voluminous Kisakata debris avalanche, which reached the Pacific coast.

1974 eruption
"After a long period of inactivity (since 1821), Tyokai volcano blew up on 1 March" reads the beginning of a bulletin received by the Smithsonian Institution on 1 April 1974.
The eruption took place in 2 phases, at the beginning of March and at the end of April 1974 and consisted in phreatic explosions generating mud flows at the snow-covered summit of Chokai volcano. It followed 153 years of dormancy. No magma reached the surface, but a very shallow intrusion was the cause of the eruptionn. ...more

1800-1804 eruption and fatalities
An eruption began at Kojin-yama crater and built a lava dome (Shinzan). The eruption caused fatalities when climbers were killed by ballistic blocks ejected during an explosion in 1801.

See also: Sentinel hub | Landsat 8
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