Mount Nasu - Nasu-dake

The main peak of the Nasu volcanic group, the leader of the Nasu volcanic belt. Also known as Chausudake, it is 1,915 meters above sea level. It is located on the western edge of Nasu Town in northern Tochigi Prefecture. The Nasu Mountains include the five Nasu mountains, Sanbonyari-dake (1,917 meters, highest peak), Asahi-dake, Nasu-dake, Nangetsu-san, and Kuroodani-dake, which are lined up from north to south, and Shirazasa-yama further south. Nasu-dake is a Quaternary stratovolcano mainly composed of pyroxene andesite, with granodiorite, quartz porphyry, Tertiary tuff, and sandstone as its base. Nasu-dake is a lava dome and the newest of the peaks, with only eight eruptions since recorded history (the oldest in 1397 and the latest in 1963). All of the eruptions were explosive, with the major eruption in 1410 (Oei 17) resulting in the deaths of over 180 people from volcanic bombs, landslides, and mudflows. There are many sour vents inside and outside the central cone, and the explosion crater on the western slope, known as Mugen Jigoku, is particularly active. The group of sour vents at the eastern foot of the mountain, known as Sessho-seki, is also famous. The mountainside and foot of the mountain are rich in hot springs, and have long flourished as therapeutic baths, but in recent years tourism has progressed. Take a bus from JR Tohoku Shinkansen Nasushiobara Station or Tohoku Main Line Kuroiso Station to Nasudake Sanroku Station. It takes 3 minutes by ropeway, and then another 40 minutes on foot to reach the summit. In 1950 (Showa 25), it was incorporated into Nikko National Park.

[Akira Suwa]

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

那須火山帯の盟主である那須火山群の主峰。別名茶臼岳(ちゃうすだけ)ともいい、標高1915メートル。栃木県北部の那須町西端にある。北―南に並ぶ三本槍(やり)岳（1917メートル、最高峰）、朝日岳、那須岳、南月(なんげつ)山、黒尾谷(くろおだに)岳の那須五岳と、さらに南の白笹山(しろざさやま)を含めて那須山とよび、花崗閃緑(かこうせんりょく)岩、石英斑(はん)岩や第三紀の凝灰岩や砂岩などを基盤とするおもに輝石安山岩からなる第四紀の成層火山。那須岳は溶岩円頂丘で、諸峰中でもっとも新しく、有史以後の8回の噴火（最古は1397年、最新は1963年）は那須岳に限られる。すべて爆発型噴火で、とくに1410年（応永17）の大噴火では、噴石・山崩れ・泥流で、死者180余人を出した。中央火口丘の内外に硫気孔が多く、西側斜面の爆裂火口「無間(むげん)地獄」はとくに活発である。東側山麓(さんろく)の硫気孔群「殺生石(せっしょうせき)」も著名である。山腹・山麓は温泉に富み、昔から湯治場として栄えてきたが、近年は観光開発が進んだ。JR東北新幹線那須塩原駅、東北本線黒磯(くろいそ)駅から那須岳山麓駅までバス。ロープウェーで3分、さらに徒歩約40分で登頂できる。1950年（昭和25）に日光国立公園に編入された。

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