Miike coalfields

It is one of Japan's largest coalfields, stretching from Omuta City in the southern tip of Fukuoka Prefecture to Arao City in Kumamoto Prefecture, beneath the seabed of the Ariake Sea. The coal is high-quality bituminous coal with 6,000 to 8,000 calories, and although it is high in sulfur, it is caking and suitable for use as raw coal. The main coal layers are the main layer of the Inari Formation of the Omuta Group of the Paleogene, the upper layer of the Nanaura Formation, and the upper two layers of the Katsudachi Formation of the Manda Group. The incline is just under six degrees, there is little slag, and the coal is relatively thick. The mine is said to have 1.68 billion tons of reserves, and was mined by the Mitsui Coal Mining Miike Coal Mine, which produced 5 million tons of coal annually, making it the largest coal mine in Japan, but closed in 1997. It is said to have been discovered in 1469 (Bunmei 1), and was developed by the Miike Domain from the end of the 18th century. In 1873 (Meiji 6), it became government-run and began Western-style mining, and in 1889 it was sold to Mitsui, which began full-scale development. In 1908, the Miike Port, with its lock gates, was completed, and along with the formation of the coal chemical complex, the mine saw remarkable development, but until 1930 (Showa 5), ​​prison labor was the basis of the work underground. As the tunnels under the sea were extended, the world's first artificial island (Hatsushima) was built in 1951 (Showa 26) for intake and exhaust, and the second artificial island (Miikejima) was built in 1970. Due to the coal mine rationalization policy brought about by the energy revolution, Miike Coal Mine rapidly became the largest built mine in Japan, undergoing mechanization and rationalization, but the opposition struggles in 1953 and 1959-1960 became historic major disputes. Coal production efficiency increased significantly, but there were also coal mine disasters, notably the large explosion at the Mikawa Pit in 1963 and the Ariake Pit fire in 1984. Employment measures and regional development after the mine closure have become major issues.

[Masaaki Ishiguro]

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

福岡県南端の大牟田市(おおむたし)から熊本県荒尾市(あらおし)にまたがり、有明海(ありあけかい)の海底下に広がるわが国有数の炭田。炭質は6000～8000カロリーの良質な瀝青(れきせい)炭で、硫黄(いおう)分は多いが、粘結性で原料炭に適する。主要炭層は古第三紀層大牟田層群の稲荷(とうか)層本層、七浦(ななうら)層上層、万田(まんだ)層群勝立(かつだち)層上二層の三層で、傾斜は六度弱、ボタが少ないうえに炭丈も比較的厚い。埋蔵量は16億8000万トンといわれ、三井石炭鉱業三池炭鉱が採鉱、出炭量は年間約500万トンでわが国最大炭鉱であったが、1997年（平成9）に閉山した。1469年（文明1）の発見といわれ、18世紀末より三池藩が開発、1873年（明治6）官営になって洋式採炭を開始、1889年三井に払い下げられて本格的開発が始められた。1908年閘門(こうもん)式の三池港が完成、石炭化学コンビナート形成とあわせて著しい発展を遂げたが、この間1930年（昭和5）まで囚人労働が坑内労働の根幹を担っていた。海底下の坑道延長に伴い、1951年（昭和26）世界初の人工島（初島(はつしま)）が入排気のためにつくられ、1970年第2人工島（三池島）がつくられた。エネルギー革命による炭鉱合理化政策により、三池炭鉱は日本一のビルト鉱として機械化、合理化が急速に進行したが、1953年、1959～1960年の反対闘争は歴史に残る大争議となった。出炭能率は著しく上昇したが、1963年の三川坑(みかわこう)の大爆発事故、1984年の有明坑火災に代表される炭鉱災害も発生した。閉山後の雇用対策や地域振興が大きな問題となっている。

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