Mount Iwaki

A cone-shaped volcano in the southwest of the Tsugaru Plain in western Aomori Prefecture. It is 1,625 meters above sea level. It is also known as Tsugaru Fuji because its shape resembles Mount Fuji. It is a composite volcano in the Chokai volcanic belt, with an outer rim developed near the summit and a central crater cone rising from it. The western half of the outer rim was lost due to explosions, and the eastern half contains Mount Chokai (1,502 meters) and Mount Ganki (1,456 meters). The central crater cone is Mount Iwaki in the strict sense. Above 500 meters above sea level, the slope is relatively steep, with several large and small explosion craters and sulfur vents, forming a valley head that carves deep into the mountain body. Below 500 meters is the foot of the mountain, and most of it is volcanic mudflow deposits and volcanic fan deposits. There have been 21 recorded eruptions, the last of which was on March 23, 1863 (Bunkyu 3). During the feudal era, the area around the foot of the mountain was used as a horse ranch and grass cutting area, and after World War II, development was undertaken, but with the exception of two or three development sites, it has not been very successful. In 1965, the Iwakisan Skyline motorway was completed from Dake Onsen at the foot of the mountain to the eighth station, and a lift was also installed to the crater of Mt. Chokai, making it easier to climb the mountain. In addition to Dake, there are hot springs at the foot of the mountain, such as Yudan and Hyakuzawa, and Iwakiyama Shrine in Hyakuzawa, Hirosaki City, attracts faith from all over Tsugaru. The people of Tsugaru have worshipped Mt. Iwaki since ancient times, and rely on it in their daily lives, such as predicting weather changes by the movement of clouds over the mountain. The "Oyama Sankei" event has been designated as an Important Intangible Folk Cultural Property of Japan, and on August 1st of the lunar calendar (for three days before and after), young people from each village at the foot of the mountain, erecting sacred wands and banners, climb the mountain to pray for a good harvest.

[Hiroshi Yokoyama]

"Mt. Iwaki of Tsugaru" by Kazuo Miyagi (1971, Morishige Publishing)

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

青森県西部、津軽平野の南西部にある円錐(えんすい)形の火山。標高1625メートル。山容が富士山に似ているところから津軽富士の別名がある。鳥海火山帯(ちょうかいかざんたい)に属する複式火山で、外輪山は山頂付近に発達し、その中に中央火口丘がそびえる。外輪山の西半部は爆発で欠損し、東半部に鳥海山（1502メートル）、巌鬼山(がんきさん)（1456メートル）がある。中央火口丘が狭義の岩木山である。標高500メートル以上は比較的急傾斜をなし、大小数個の爆裂火口や硫気孔があって、山体を深くえぐる谷頭となっている。500メートル以下が裾野(すその)で、大部分は火山性の泥流堆積物(たいせきぶつ)と火山性扇状地の堆積物である。噴火は記録のうえでは21回あり、最後の噴火は1863年（文久3）3月23日である。山麓(さんろく)一帯は藩政時代には馬の牧場や草刈り場として利用され、第二次世界大戦後は開拓が行われたが、二、三の開拓地を除いては十分な成果をあげていない。1965年（昭和40）に山麓の嶽(だけ)温泉から八合目まで自動車道岩木山スカイラインが完成し、鳥海山噴火口までリフトも架設され、容易に登山ができるようになった。山麓に嶽のほか、湯段(ゆだん)、百沢(ひゃくざわ)の温泉があり、弘前(ひろさき)市百沢の岩木山神社(いわきやまじんじゃ)は津軽一円の信仰を集めている。津軽の人々は古くから岩木山を信仰し、天候の変化を山にかかる雲の動きで予知するなど、日常生活のよりどころとしている。「お山参詣(さんけい)」の行事は国の重要無形民俗文化財に指定され、旧暦8月1日（前後3日間）、山麓の集落ごとに若者たちを中心に、御幣や幟(のぼり)を立てて豊作祈願のため山に登る。

［横山　弘］

『宮城一男著『津軽の岩木山』（1971・森重出版）』

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