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Shikotsu-Tōya NP., Hokkaido
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Between 1943 and 1945, flat wheat fields on Usu’s flank rose into a volcano whose summit reached nearly 400 m above sea level. The first steam explosion came on 23 June 1944, after months of earthquakes.
At Fukaba, the ground rose by as much as 50 m and destroyed the settlement. Railway crews repeatedly shifted the nearby Iburi Line east to keep it running.
With film scarce during WWII, postmaster Masao Mimatsu fixed his viewpoint with fishing lines and a chin-rest board, sketching the growing volcano day by day. His diagram won international acclaim in Oslo in 1948.
Showa-shinzan’s red-brown “natural brick” is actually the original clay soil, baked hard by heat. Stream-rounded stones on the slope offer another clue: the old farmland itself was lifted into the mountain.
Sobetsu locals turned winter’s troublesome snow into a sport: the first Showa-shinzan Yukigassen tournament was held here in 1989. Teams use 90 snowballs per set, while volunteers serve hot tonjiru, or pork soup.
To protect the newly formed volcano, postmaster Mimatsu used his own money to buy the uplifted land. Showa-shinzan remains privately owned today—an unusual legacy for a Special Natural Monument.
Showa-shinzan’s shape has two chapters: magma first pushed older ground into a broad, low “roof mountain”; later, a central dome of new lava rose through it. The jagged peak is not one simple pile of lava.
Japan designated Showa-shinzan a Special Natural Monument on 19 June 1957, less than 12 years after its growth stopped—a remarkably swift formal recognition of a newborn volcano.
