Around a World Heritage Site: The Gunkanjima Guide [Complete Edition] » The coalmine

The Hashima coalmine

In the 20th century, the role of coal, which was even called black diamond, was great, and coalmining was one of the largest resource industries that made the Japan of today. Among the coalmines, Gunkanjima produced the highest quality coal in Japan and made a significant contribution to the steelmaking industry. We present the role of the Gunkanjima coalmine along with its history.

The Gunkanjima /Hashima Coalmine that supported Japan’s industrial revolution

Inside the mine
Photo courtesy of the Gunkanjima Digital Museum

The Hashima Coalmine was a submarine coalmine developed by Mitsubishi as a full-fledged modern coalmine, inheriting the technology of the Takashima coalmine. Since the coal bed was right under the island, a gallery was dug 1,010 m below sea level. The coal was excavated along the coal bed and carried up to the surface by a hoist

The miners did a lot of work manually in a hot and humid mine with the temperature reaching 30 to 36°C and the humidity 90%, and the seam was steep at 40 to 60°, making it difficult to install machinery. It operated three shifts of eight hours 24 hours a day, and Gunkanjima was brightly lit even at night.

Photo courtesy of the Gunkanjima Digital Museum

The extracted coal was transported on a belt conveyor from a tipple next to the second shaft to the coal depot. From the coal depot, the coal was loaded onto a coal carrier and shipped. Poor-quality coal and rocks, called coal waste, were dumped through a belt conveyor to the west coast, where the settlement was located. Everything from extracting to clean coal took place on this small island.

The history of Japan and coalmines

The term coalmine refers to a base (mine) where coal buried underground is extracted. Areas where coalmines are concentrated are called coalfields and they are clustered in Hokkaido and Kyushu in Japan.

The stratigraphic composition of coalmines in Japan is more complex than that of large-scale coalmines in the United States and Australia. Therefore, their characteristic is that coal is often located deep underground. As a consequence, coalminers dug tunnels that could be as long as a few kilometers. Their working conditions were poor, and there were accidents caused by methane and coal dust exploding in the mine, which led to numerous fatalities.

Coalmining became more active after the Meiji period. During the Edo period, coalmining technology had been limited to digging coal exposed on the surface or excavating coal on a shoestring through narrow holes, and coal had been used as a substitute for firewood.

However, when western technology poured into Japan in the wake of the Meiji Restoration, modern technology in coalfield regions took off rapidly. Coalmining evolved into a basic industry that supported the modernization of Japan. Its scale was to expand further, and extraction technologies were to be developed. The technology is still used in many industries today.

The history of coalmining experienced a decline as the Showa period began. Coal used for fuel etc. went through repeated cycles of increased production and downturns with wars such as the Manchurian Incident in 1931 and the Pacific War in 1941.

During the wartime in 1940, the mine recorded the highest coal output in the country. After the war, it implemented a priority production system to increase coal production, thus contributing to the rebuilding of domestic industry after the defeat in World War II.

However, the priority production system led to overproduction. Small and medium-sized mines were forced to merge into large-scale mines or close down. In addition, there were problems such as massive imports of oil in 1950 (the energy revolution), two oil crises, the inability to compete with foreign products in terms of cost, and the fact that mining sites became increasingly remote. As a result, coalmining declined in the 1960s, and most coalmines closed down at the end of the 20th century.

The benefits brought by coal

Put simply, coal is a product of fossilized prehistoric plant matter that has turned into a mass capable of burning. Specifically, it is a collective term for substances that have formed out of withered plants that fell to the ground and accumulated underground before they could decay, and then slowly degraded over time.

In Japan, too, there are records in the form of legends of burning stones in the Chronicles of Japan, but a recorded discovery of coal dates to the mid-1400s. It is said that it was discovered by farmers in Omuta, present-day Fukuoka prefecture, in a place known as the Miike Coalmine.

It is reported that Japan still holds coal deposits amounting to 20 billion tons, and a large portion can be mined. About 80% of it is located in Kyushu. The coal formation time is 200 to 300 million years shorter than overseas, but the carbonization rate is high due to geothermal heat from volcanoes, and it is as good as coal from older periods.

Initially, coal was primarily used for personal fuel. Eventually, an industry would develop and rely on heat from coal for the required energy. Therefore, demand for coal rapidly increased and it became an important resource used by households and industries alike.

There are more reserves of coal than any other fuels and it is not unevenly distributed like oil. As an energy resource that can be mined widely throughout the world, it is used as fuel for steam boilers in power generation, in steelworks, and as fuel at various factories. By the way, there are concerns that oil will be depleted in 50 years, but coal can be mined for 112 years.

Coal types are generally classified by the degree of carbonization. Anthracite, which has the highest degree of carbonization, and bituminous coal, which has the second highest degree of carbonization, are also known as “black diamond” and are important energy sources that support Japan.

The coal produced on Gunkanjima is strongly caking coal that has the highest thermal power among bituminous coals. It has great combustive power and is also used as a raw material for coke required in steelmaking. Strongly caking coal is one of the most expensive coals traded, so it can be said that it was one of the factors that kept attracting people to Gunkanjima.

In many cases, it is impossible to land due to sea conditions and bad weather. However, with the cooperation of the Gunkanjima Concierge, which boasts a high landing rate of 94.7% (*), we present a report on the landing tour that we participated in. We will acquaint you with all the charms of Gunkanjima, not to mention the highlights of the tour!

※Landing results from 2011 to 2018