Mount Unzen, Active volcano in Shimabara Peninsula, Nagasaki Prefecture, Japan
Mount Unzen sits on Shimabara Peninsula in Nagasaki Prefecture and consists of several peaks and lava domes formed by repeated eruptions over thousands of years. Steam still rises from cracks and craters, and sulfur vents and fumaroles at the foot of the mountain boil water and release gas into the air.
A major eruption shook the mountain in 1792 and triggered a landslide that plunged into the sea, generating a tsunami that killed over 15,000 people. Between 1990 and 1995 a new phase of activity produced a fresh lava dome and sent pyroclastic flows into several nearby settlements.
The mountain holds Special Place of Scenic Beauty status and appears in Japan's prestigious lists, including Top 100 Geological Sites and 200 Famous Mountains.
Hiking trails lead upward from the town of Unzen Onsen to the summits and through Jigoku Valley, where escaping gases and boiling water emerge from the ground. Starting early in the morning offers the best chance to see the coastline before fog settles in later in the day.
A new peak called Heisei Shinzan emerged during the eruptions of the early 1990s and changed the outline of the entire mountain range. Visitors can still read the growth of this dome in the fresh rock surfaces, which stand out clearly from the older material around them.
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