Mount Unzen

Mount Unzen is an active volcanic complex on Japan’s Shimabara Peninsula. Its 1792 collapse triggered a tsunami, and its 1991–1995 eruption produced deadly pyroclastic flows.

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Lava dome: A steep-sided mound formed when viscous lava accumulates near a volcanic vent. Unzen’s 1990s eruption built a lava dome that repeatedly collapsed into pyroclastic flows.
1792 Unzen disaster: A volcanic collapse and tsunami disaster that struck Shimabara and nearby communities in 1792. The Mayuyama collapse and resulting tsunami killed thousands around Unzen.
Unzen Graben: A tectonic depression associated with crustal extension in the Unzen volcanic area. Its structure helps explain the location and broad form of the volcanic complex.
Kiyoo Mogi: A Japanese seismologist known for research on earthquake deformation and volcanic activity. Mogi’s deformation model helps interpret ground movement monitored at volcanoes such as Unzen.
Unzen Volcano Museum: A museum in Shimabara that presents the history and hazards of Mount Unzen. It documents the 1991–1995 eruption and its consequences for local communities.
Pyroclastic flow: A fast, ground-hugging current of hot gas, ash, and volcanic fragments. Dome collapses at Unzen generated the lethal flows of June 1991.
1991 Unzen eruption: An eruption of Mount Unzen that began in 1990 and produced repeated pyroclastic flows from 1991 to 1995. Its pyroclastic flows killed 43 people, including scientists and journalists, in June 1991.
Japanese island arc: A chain of volcanic islands formed above subduction zones around the Japanese archipelago. Unzen is one of the active volcanoes produced by tectonic processes around Japan.
Volcanic disaster mitigation: Measures that reduce harm from volcanic hazards through monitoring, planning, warnings, and evacuation. Unzen’s evacuation zones and monitoring illustrate mitigation during prolonged dome growth.
Volcanic hazard map: A map showing areas potentially exposed to volcanic hazards and related risks. Unzen’s hazard planning addresses flows, lahars, and other threats from the complex.