Volcanic Activity in the Azuma Mountain Range
The Azuma volcanic group formed between 300,000 and 6,000 years ago from repeated eruptions. Some of the peaks in the mountain range remain active. Mt. Issaikyo (1,949 m) is the most active volcano in the Tohoku region and continually emits gases from the Oana Crater, one of several fumarolic areas on the mountain. The volcano is closely monitored, and volcanologists believe it has a high potential for eruption.
A major eruption of Mt. Issaikyo in 1893 caused the death of two engineers who were surveying the area. A column of hot volcanic ash and gas rose 2,000 meters into the sky, and volcanic ash and other fragments were ejected from the Tsubakurozawa craters in large quantities. The last eruption of Mt. Issaikyo, in 1977, was relatively minor but still caused volcanic ash to fall as far as 4 kilometers away.
The Azuma volcanic zone is one of 50 areas in Japan where volcanic activity is constantly monitored. The Japan Meteorological Agency classifies active volcanoes using a five-level volcanic alert system. Level one is the lowest, and level five is the highest. The Jododaira area usually stays at level one (potential for increased activity). However, when the alert level around Mt. Issaikyo rises to two or higher, the entire Jododaira area is closed to visitors, including the Bandai-Azuma Skyline.
Before visiting the area, check the Japan Meteorological Agency’s website for volcanic warnings: (https://www.jma.go.jp/en/volcano/map_1.html).