On-take volcanOn-take (御嶽山 Ontake-san) is a massive stratovolcano and the second highest in Japan. It is located at the southern end of the Northern Japan Alps.
Its first historic eruption occurred in 1979. A landslide in 1984 was not related to an eruption and produced a debris avalanche and lahar running down valleys south and east of the volcano.
On-take volcano is one of the holy mountains of Japan and the destination for religious pilgrimage since 1792.
Introduction:On-take's summit cone was built in a largely buried 4 x 5 km caldera. It lies at the southern end of the Norikura volcanic zone, which extends northward through Norikura volcano to Yake-dake volcano.
The older volcanic complex of Ontake consists of at least 4 major stratovolcanoes that were constructed from about 680,000 to about 420,000 years ago, after which On-take was inactive for more than 300,000 years.
The broad, elongated summit of the younger edifice is cut by a series of small explosion craters along a NNE-trending line. Several phreatic eruptions from On-take post-date the roughly 7300-year-old Akahoya tephra from Kikai caldera.
Source: On-take volcano information from Smithsonian / GVP
1979 first historic eruption
Around 5:00 on 28 October 1979 the first historic eruption of On-take volcano occurred from a fissure on the southwestern slope of the main peak, Kengamine.
The eruption produced a tephra column of 1500 meters and there was ashfall in Maebashi City 150 km away. A 30 m diameter crater and 9 small craters on a NW-SE lline were formed above the eruptive fissure.
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