Arafune-Azumaya Cold Storage Facilities

Arafune-Azumaya Cold Storage Facilities (, Arafune-Azumaya fūketsu sanshu chozō sho ato) are natural refrigerators used in silkworm production in association with the Tomioka Silk Mill in the towns of Shimonita and Nakanojō, Gunma Prefecture Japan. They are jointly designated as a National Historic Site and, together with the Tomioka Silk Mill, inscribed on the UNESCO World Heritage List as part of the serial nomination Tomioka Silk Mill and Related Sites

Following the Meiji restoration, the new Meiji government needed export products to raise the monies necessary for the industrialization and westernization of Japan. Goods which were already produced in Japan and which could be exported for good profit included tea, silk thread and silkworm cocoons. Especially with the spread of the silkworm disease called pébrine in France and Italy, and the turmoil in China caused by the Taiping Rebellion, Japanese silk was in high demand. In 1862, shortly before the Meiji restoration, raw silk and silkworm cocoons accounted for 86% for Japan's exports. However, soon after the Meiji restoration, overproduction, and the recovery of silk producing areas in Europe and China led to a drastic fall in raw silk prices. The Meiji government countered by changing its focus to silk products, such as silk thread and cloth, to increase the value of its silk exports. The opening of the Tomioka Silk Mill in 1872 saw a boom in sericulture in Gunma Prefecture and surrounding areas, and the raising of silkworms became the primary activity for many farmers. In order to adjust the hatching time of silkworms, a number of wind caves were modified for use as natural refrigerators for cold storage of silkworm eggs. Cool air is produced by wind passing through rock crevices filled with snow accumulated over winter. Even in the summer when the outside temperature is over 20 degrees Celsius, the temperature in the cave remains a constant couple degrees above freezing. This enabled the number of silkworm "crops" to be produced each year to be increased from one to two or even three, thus greatly contributing to the increase in the production of raw silk cocoons to meet the ever increasing demand. When

Cave data from Wikidata (CC0). Summary from Wikipedia (CC BY-SA).