Yatsugatake, central Honshu, consists of many domes and cones.
It has been the site of many gigantic landslides.
The oldest debris avalanche, which took place on the northern
slope, is called the "Kan'nonji mud flow deposit"
It covered an area of 90 km² .
This debris avalanche might have originated at another volcano.
The next debris avalanche occured about 0.9 million years
ago and flowed down along the Aikigawa river.
The biggest debris avalanche in Japan, named the Nirasaki
debris avalanche occurred and is characterized by large hummocky hills.
The most recent of 0.3 km² area occurred on the eastern
slope of Tengu-summit in 888 AD
It flowed over 12 kilometers along the Otsukigawa River.
It was called the "Otsukigawa debris avalanche".
The following stamp was issued 21st March, 1968
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