Mount Chokai

A volcano towering over the border between Akita and Yamagata prefectures. It is 2,236 meters above sea level (Shinzan summit). The summit is in Yamagata prefecture. It is the main peak of the Chokai volcanic belt, and the second highest mountain in the Tohoku region after Hiuchigatake (2,356 meters). It is a beautiful stratoconical volcano that reaches all the way to the Japan coast, and is also known as Dewa Fuji and Akita Fuji. Dewayama is a volcano that erupted above ground, and is composed of pyroxene andesite, peridotite, and clastic materials. It is a complex of two double volcanoes, an old one and a new one. The new one is surrounded by outer rim mountains such as Shichiko-san (2,230 meters) and Fushiogami-dake. In a U-shaped explosion crater with a diameter of about 3,500 meters opening to the north, there are two central crater cones (lava domes) of Shinzan and Kojin-ga-take. Senjadani between the outer rim mountains is famous for its snowy valleys. Shinzan was born in 1801 (Kyowa 1) and is also called Kyowa-dake. The old volcano is also called Nishi-Chokai-san, and has Sho-ga-take and Gassan-mori as outer rim mountains, Nabe-mori (1,652 meters) and Sensu-mori as central crater cones, and Tori-no-umi crater lake. The eruption in 578 (7th year of Emperor Bidatsu's reign) is the second oldest recorded eruption after the eruption of Mt. Aso in 553 (14th year of Emperor Kinmei's reign), and there were over a dozen eruptions thereafter until 1821 (4th year of Bunsei). A small eruption in 1974 (49th year of Showa) occurred in the area from Shinzan to Kojingatake, and small-scale volcanic mudflows also occurred. Since ancient times, it has been a popular place for religious climbers as a sacred mountain, and even today Mt. Chokai Omonoimi Shrine is located on the summit. In the Middle Ages, it also developed as a training ground for ascetic practices. The view from the summit is magnificent, and there are many rare alpine plants such as Chokaifusuma. Golden eagles have been confirmed to live on the southern foot of the mountain, and the Ministry of the Environment has established a bird of prey protection center here. Spring skiing is also enjoyable. The area is part of the Chokai Quasi-National Park, and the Chokai Blue Line Expressway connects Fukuura, Hokotate, and Kisakata. There are hiking trails including the Kisakata trail, the Yajima trail, the Fukuura trail, and the Yunodai trail, but these are for those with good walking skills. As it is an independent peak close to the sea, the weather changes drastically, so caution is required when climbing.

[Akira Suwa]

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

秋田・山形県境にそびえる火山。標高2236メートル（新山(しんざん)頂上）。山頂部は山形県に属す。鳥海火山帯の主峰で、燧ヶ岳(ひうちがだけ)（2356メートル）に次ぐ東北地方第二の高山。日本海岸まで裾野(すその)を引く秀麗な成層・円錐(えんすい)火山で、出羽富士(でわふじ)、秋田富士の名がある。出羽山地上に噴出した火山で、輝石安山岩、橄欖(かんらん)岩と砕屑(さいせつ)物からなる。新旧二つの二重式火山が複合したもので、新火山は七高(しちこう)山（2230メートル）、伏拝(ふしおがみ)岳などの外輪山に囲まれ、北に開いた直径約3500メートルのU字形の爆裂火口内に、新山、荒神ヶ岳(こうじんがたけ)の両中央火口丘（溶岩円頂丘）があり、外輪山との間の千蛇谷(せんじゃだに)は雪渓で名高い。新山は1801年（享和1）に誕生し、享和岳(きょうわだけ)ともいう。旧火山は西鳥海山ともよばれ、笙(しょう)ヶ岳、月山(がっさん)森などを外輪山とし、鍋(なべ)森（1652メートル）、扇子(せんす)森の中央火口丘と、鳥ノ海の火口湖がある。578年（敏達天皇7）の噴火は、553年（欽明天皇14）の阿蘇(あそ)山噴火に次ぐ古い噴火記録で、以後、1821年（文政4）まで十数回の噴火をみた。1974年（昭和49）の小噴火は新山から荒神ヶ岳地域でおき、小規模の火山泥流も発生した。古くから霊峰として信仰登山が盛んで、現在も山頂に鳥海山大物忌神社(ちょうかいさんおおものいみじんじゃ)がある。また中世は修験(しゅげん)道場として発展した。山頂からの展望は雄大で、チョウカイフスマなどの珍しい高山植物も豊富である。南麓ではイヌワシの生息が確認され、環境省猛禽(もうきん)類保護センターが設置されている。春スキーも楽しめる。一帯は鳥海国定公園域で、吹浦(ふくら)―鉾立(ほこたて)―象潟(きさかた)を結ぶ自動車道路鳥海ブルーラインも通じる。登山コースは象潟口、矢島口、吹浦口、湯ノ台口などがあるが健脚向きであり、海に近い独立峰のため気象の変化が激しく、登山には注意を要する。

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