Mount Tarumae Lava Dome was added to Your Favorites!
Shikotsu-Tōya NP., Hokkaido
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After months of rumbling and 2 explosive blasts, a new hill was spotted at the summit on April 19, 1909. By May 2, the dome measured 450 m across and 134 m high.
Tarumae's present dome had a predecessor: one formed in 1867, then a 1874 eruption destroyed it and opened a roughly 180-m crater. The dome visitors recognize today rose in 1909.
The 1909 dome reached a measured 457°C on May 2, only days after it appeared. JMA still records fumaroles and geothermal heat around it—this landmark sits atop a living volcano.
At first, the new dome resembled a bun; later its summit subsided and fallen blocks accumulated around the base. Japan’s Cultural Heritage Online says the result resembles an overturned cup.
On April 12, 1909, pumice up to 3 cm across fell as far as 20 km from Tarumae, and ash was observed in Sapporo, about 40 km away—before the dome appeared.
Two historical “before” views show how new the dome is: neither Shibue Chōhaku’s 1799 sketches nor an 1804 Japanese mountain album depicts a summit dome or rising steam.
The Ainu-derived name Tarumae likely began with a river, not the mountain: Tomakomai’s guide traces it to taor-oma-i, “a place with a high riverbank,” for the Tarumae River, whose source is here.
Hokkaido designated the dome a Natural Monument in 1967. Japan’s cultural-property record describes it as scientifically valuable worldwide, noting that its formation and volcanic form differ from Showa Shinzan’s.
