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Fuji-Hakone-Izu NP, Tokyo
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On Nov 15, 1986, lava fountains filled a shaft about 230 m deep and 300 m wide. By Nov 19, the rising lava lake spilled over the crater rim and flowed onto the caldera floor.
The A-flow tongue spread across the caldera floor and stopped with a front about 5 m thick. Its jagged aʻa surface formed as the crust cooled and broke while hot lava kept moving beneath it.
The A flows spilled from the summit lava lake, but not all 1986 lava formed that way: researchers also described flows made from lava-fountain fragments and lava squeezed from a hot, welded cinder cone.
Within about a year, Hachijo itadori was growing on bare 1986 lava—earlier than the usual textbook sequence of lichens and moss first. Its winged seeds ride island winds, while roots and fallen leaves help build soil.
Beside the 1986 lava are flows from 1951 and 1777–78. Their different plant communities let visitors compare how vegetation returns to bare lava over decades and centuries.
Islanders and visitors crowded the trails to watch the fountains and flowing lava. On Nov 21, new fissures opened beyond the summit caldera, and the spectacle turned into an emergency.
The later C flow—not the summit A flow—ran toward Motomachi on Nov 21 and stopped about 70 m from the town crematorium. By the next day, about 11,000 residents and 2,000 visitors had been evacuated.
Crews sprayed water near the separate C flow, but experts warned that visibly red-hot lava moving more than 1 m per hour would be extremely difficult to immobilize. Fire prevention became the priority.
Mihara’s fiery glow has long been revered on Oshima as Gojinka (御神火), or “sacred fire.” The name carries local respect for the same living volcano whose lava reshaped this landscape.
