Mount Bandai

A volcano located in the northern part of Fukushima Prefecture, straddling the towns of Inawashiro and Bandai in Yama County and the village of Kitashiobara. It is 1,816 meters above sea level. It is a pyroxene andesite stratovolcano based on Neogene sandy, muddy and tuffaceous sedimentary rocks, and has been active for about 30,000 years, with only two phreatic eruptions since recorded history. At the top is the Numanodaira crater, about 1.5 kilometers in diameter, surrounded by the main peaks Obandai, Kushigamine and Akahaniyama, and inside there are large and small swamps and high moors. There is a legend that the crater exploded in 806 (Daido 1), and Lake Inawashiro was formed to the south at that time, but this is hard to believe. Mount Kobandai, which formed the northern wall of the crater, collapsed in a sudden explosion on July 15, 1888 (Meiji 21) (more than 1.2 cubic kilometers), creating a U-shaped explosion caldera about 2 kilometers in diameter. A large debris flow was pushed out to the northern foot of the mountain at a speed of about 80 kilometers per hour, burying various settlements (461 people died) and creating many lakes and marshes, including the three lakes of Urabandai. This special type of eruption, typified by a large phreatic explosion after a long period of dormancy, is called a Bandai-type eruption. In 1938 (Showa 13) and 1954 (Showa 29), the caldera walls collapsed, causing damage. Sulfur vents are scattered on the caldera walls and inside the Numanodaira crater. Iwahashi Shrine on the southern foot enshrines the mountain spirit, and the character for "Iwa" is synonymous with "Hashi" (ladder), meaning a rocky ladder ascending to the heavens. He is the god of agriculture. He is revered as the Fuji of Aizu and is also featured in the folk song "Aizu Bandaisan." It is part of Bandai-Asahi National Park. The shortest hiking trail is from the Happodaiguchi trail, but you can also climb from the Inawashiroguchi trail, Okinajimaguchi trail, Urabandaiguchi trail, Kawakamiguchi trail, and others. The Wakamatsu Meteorological Observatory constantly monitors the volcano.

[Akira Suwa]

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

福島県北部、耶麻(やま)郡の猪苗代(いなわしろ)、磐梯の2町と北塩原村にまたがる火山。標高1816メートル。新第三紀の砂質、泥質と凝灰質の堆積(たいせき)岩を基盤とする輝石安山岩の成層火山で、いまから3万年ほど前から活動してきたらしく、また、有史以後の噴火は水蒸気爆発2回だけである。頂部には、主峰の大磐梯や櫛ヶ峰(くしがみね)、赤埴(あかはに)山などで囲まれた直径約1.5キロメートルの沼ノ平火口があり、内部に大小の沼や高層湿原がある。火口は806年（大同1）に爆発、そのとき南方の猪苗代湖ができたという伝説があるが、信じがたい。火口の北壁をなしていた小磐梯山は、1888年（明治21）7月15日に突発した大爆発で崩壊し（1.2立方キロメートル余）、直径約2キロメートルのU字形の爆発カルデラができた。大岩屑(がんせつ)流が時速約80キロで北麓(ほくろく)に押し出し、諸集落を埋没し（死者461人）、裏磐梯三湖などの多数の湖沼を生じた。長い休眠後におきたこの大水蒸気爆発を典型とする特殊な噴火形式を磐梯式噴火という。1938年（昭和13）と1954年（昭和29）に、カルデラ壁大崩壊で被害を出した。カルデラ壁や沼ノ平火口内には硫気孔が散在。南麓の磐椅神社(いわはしじんじゃ)は山霊を祀(まつ)るが、椅は梯と同義で、天に昇る磐のはしごの意。農業神である。会津富士と仰がれ、民謡「会津磐梯山」でも親しまれ、磐梯朝日国立公園に属す。八方台口からの登山路が歩行距離最短だが、猪苗代口、翁島(おきなじま)口、裏磐梯口、川上口などからも登れる。若松測候所が常時火山観測中。

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