stratovolcano 1131 m / 3,711 ft Hokkaido, Japan, 42.06°N / 140.68°E Eruption list: 2000, 1998, 1996, 1942, 1937, 1935 (?), 1929 (Plinian), 1928 (?), 1924, 1923, 1922,
1919, 1905, 1888, 1856 (Plinian), 1784, 1765, 1710 (?), 1694 (Plinian), 1640 (Plinian)
radiocarbon-dated: 4350 BC (?), 4500 BC ± 150 years (Plinian), 4600 BC ± 50 years (Plinian)
Small ash eruptions occurred at Komaga-take volcano on 4 and 18 September 2000.
A small phreatic eruption occurred at Komagatake volcano on 25 October 1998, producing an ash cloud rising 1200 m above the crater.
Following increased seismic tremor and inflation, a small phreatic eruption from the 1929 crater occurred on 5 March 1996, producing an ash cloud of 300-500 m height. Light ash fall was recorded up to 10 km from the summit.
The total erupted mass of tephra was estimated at about 25,000 tons.
Source: Smithsonian / GVP monthly reports
1929 Plinian eruption
The most recent major magmatic eruption of Komaga-take volcano occurred on 17 June 1929 and continued with minor activity for 7 weeks. It ranks as a Plinian eruption and produced pumice fall and pyroclastic flows. The eruption killed 2 people and caused widespread damage.
[hide] The eruption started violently on 17 June 1929 and quickly formed a broad and tall eruptive column, generating pyroclastic flows in all directions from a new crater, a small circular pit located in the center of the broad summit platform.
A pyroclastic flow passed within 200 m of the village of Yakeyama. The longest pyroclastic flows ran down the N flank of Komagatake and reached the sea at about 6.5 km distance from the crater.
The most vigorous activity was over after daybreak on 18 June 1929, but minor activity continued until 6 September 1929.
Source: Boris Behnck's KOMAGATAKE volcano page
1640 AD Plinian eruption and tsunami
The 1640 eruption was (probably) the largest in Japan's history and started a period of more frequent explosive activity. It deposited ash as far away as central Honshu and produced a debris avalanche that reached the sea. The resulting tsunami caused 700 fatalities.
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