Hōei eruption of Mount Fuji

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Map of volcanic ash fall during the Hoei eruption
Map of volcanic ash fall during the Hoei eruption
Mount Fuji, showing the Hōei crater
Mount Fuji, showing the Hōei crater

The Hōei Eruption of Mount Fuji (宝永大噴火 Hōei dai funka?) occurred in 1707 (the fourth year of the Hōei era). Although it brought no lava flow, the Hoei eruption released some 800 million cubic meters of volcanic ash, which spread over vast areas around the volcano, even reaching Edo almost 100 km away. Cinders and ash fell like rain in Izu, Kai, Sagami, and Musashi provinces.[1]

The eruption occurred on Mount Fuji's east–north-east flank and formed three new volcanic vents, named No. 1, No. 2, and No. 3 Hōei vents. The catastrophe developed over the course of several days -- an initial earthquake and explosion of cinders and ash was followed some days later with the more forceful ejections of rocks and stones.[2] Mount Fuji has not erupted since.

Hokusai's One Hundred Views of Mount Fuji includes an image of the small crater which developed from a secondary eruption site on the southwestern slope. This was called Hōeizan because the eruption occurred in the fourth year of Hōei.[2]

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[edit] Secondary disasters

In the year following the Hōei eruption, a secondary disaster occurred when the Sakawa flooded due to sediment build-up resulting from the ash fall.

Volcanic sands fell and widely covered the cultivated fields east of Mount Fuji. To recover the fields farmers cast volcanic products out to dumping-grounds and made sand piles. The rain washed sand piles from the dumping grounds away to the rivers again and again and made some of the rivers shallower, especially into the Sakawa, into which huge volumes of ash fell, resulting in temporary dams. Heavy rainfall on August 7 and 8, 1708, the year following the Hōei eruption, caused an avalanche of volcanic ash and mud and broke the dams, flooding the Ashigara plain.


[edit] Notes

  1. ^ Titsingh, Isaac. (1834). Annales des empereurs du japon, p. 416.
  2. ^ a b Smith, Henry. (1988). Hokusai: One Hundred Views of Mt. Fuji. p. 197.

[edit] References

  • Source of map: 宝永噴火降灰分布実績図(出典:富士山防災協議会)

[edit] See also

[edit] External links