Japanese website
last update: October 12, 2004 (JST)

Geological Survey of Japan, AIST

MT.ASAMA ERUPTION
September 1, 2004


Eruption plume from Mt. Asama on 16 September (photo by M.Owada, GSJ)

An explosive eruption occurred on 14 November
Moderate explosive eruption ocurred at 20:59, 14th November. Ash and lapilli were spread mainly in E flank of the volcano.
Ash-fall covered northern part of Kanto area, more than 100 km from the volcano.

A weak explosive eruption occurred on 10th, October
Minor explosive eruption ocurred at 23:10, 10th October. Small amount of ash and lapilli were spread mainly in NNE flank of the volcano.


Minor ash eruption occurred twice on 1st, October.


An explosive eruption occurred on 23 September
Moderate explosive eruption ocurred at 19:44, 23th September. Small amount of ash and lapilli were spread mainly in NE flank of the volcano.


Eruptions Repeated Again from 14 to 18 September.


Eruption of Asama, the daybreak on 17th September. Photo by Dr.S.Nakano (GSJ).

Minor ash eruptions occur intermittently from 14th September and continued till 21:03, 18th. Colored eruption clouds emitted from the summit crater and drifted eastward. Ash-fall covered southern part of Kanto area, more than 150 km from the volcano. Activity of the eruption became peak in the afternoon of 16th Septemeber and glassy - pumiceous ash were issued continuously. Minopr ash eruptions continue to 18th September.

Ash grain erupted 14-16 September (Japanese page)




Drifting eruption cloud of Asama volcano, from GSJ office building in Tsukuba, ca. 150 km east of the Volcano.
17:51, 14 September. Photo by Dr. A.Tomiya (GSJ)


Mt. Asama Erupted on 1st September, After 21 Years Pause.

An explosive eruption occurred from the summit crater of Mt.Asama(2,568m) at 20:20 September 1st (Japan local time).
Eruption was a single vulcanian explosion. According to the report of JMA, red-hot blocks spread ~ 2km from the summit and caused many wild fires. Eruption cloud drifted to NE by strong wind and volcanic ash covered a narrow and elongated area. Ash-fall reached ca 250 km from the volcano and reached to Pacific Ocean.
Total amount of the eruptive product is estimated ca 100,000 ton (by GSJ AIST).





lapilli issued during the September 1st eruption (collected ca 4km NE from crater)



Bread-crust bomb ejected at the September 1st eruption (GSJ)



Eruption Sequence -- Heli observation -- Tephra in field -- Ejecta 1st Sept. 14-16th Sept. -- Tephra Distribution -- Gas emission@

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This webpage is managed by Dr. N.Geshi (GSJ).