Mountains · Nagasaki
Mount Unzen
雲仙岳うんぜんだけUnzen-dakeA volcano of disaster and renewal above the Shimabara Peninsula.
Mount Unzen (雲仙岳) is a volcanic complex at the centre of the Shimabara Peninsula in Nagasaki Prefecture, whose highest point is the Heisei-shinzan lava dome at 1,483 m, formed in the eruption of 1990–1995. The volcano caused Japan's worst volcanic disaster in 1792 and the deadly pyroclastic flow of 3 June 1991.
Overview
Unzen rises at the heart of the Shimabara Peninsula, east of Nagasaki, a cluster of volcanic peaks including Fugendake, Kunimidake, Myōkendake and the young dome of Heisei-shinzan. On its western slopes lies Unzen Onsen, a hot-spring resort built around the steaming Unzen Jigoku, which in the early twentieth century became a summer retreat for foreigners from Shanghai and Hong Kong.
Unzen was part of Japan's first group of national parks in 1934. Its recent history, however, is marked by disaster: the eruption of 1990–1995 produced thousands of pyroclastic flows and debris flows that devastated the town of Shimabara and the surrounding countryside, and the dome it built is now the highest point of Nagasaki Prefecture.
Landscape and formation
Unzen is a volcanic complex within the Unzen graben, a sinking rift that crosses the peninsula from east to west. Its lavas are viscous dacite, which piles up as domes rather than flowing far; when domes collapse, they generate pyroclastic flows. The 1990–1995 eruption built the Heisei-shinzan dome, about 100 million m³ of lava, on the east side of Fugendake.
In 1792, the collapse of the older dome of Mayuyama created islets in the sea off Shimabara, the Tsukumo-jima. The Unzen Jigoku fumaroles and hot springs on the western side reflect the continuing heat below.
Highlights
Heisei-shinzan
平成新山Heisei-shinzanThe lava dome of 1990–1995, the highest point in Nagasaki, designated a natural monument in 2004; off-limits.
Fugendake
普賢岳Fugendake1,359 m, the main hiking summit, facing Heisei-shinzan across a narrow gap.
Unzen Jigoku
雲仙地獄Unzen jigokuSteaming fumarole fields in Unzen Onsen, crossed by walking paths.
Nita-tōge
仁田峠Nita-tōgeA pass with a ropeway, famous for azaleas in spring and rime ice in winter.
Mizunashi-gawa
水無川Mizunashi-gawaThe valley filled by pyroclastic and debris flows, where buried houses are preserved as a memorial park.
Ecology
Unzen's upper slopes are covered by deciduous broadleaf forest and the Miyama-kirishima azalea, while the new lava of Heisei-shinzan shows the first stages of plant colonisation. Nita-tōge is known for rime ice (muhyō) in winter.
Flora
Miyama-kirishima
ミヤマキリシマmiyama-kirishimaPink azaleas cover the slopes around Nita-tōge in May; a natural monument at Unzen.
Fugendake beech
ブナbunaA small, isolated beech stand near the summit, at the southern edge of beech in Japan.
Fauna
Japanese giant flying squirrel
ムササビmusasabiLives in the forests around Unzen Onsen.
Sika deer
ニホンジカnihonjikaCommon on the upper slopes.
Culture
Unzen was a centre of mountain Buddhism from the 8th century, with the temple Manmyō-ji said to have been founded by the monk Gyōki. In the 1620s and 1630s the Unzen Jigoku became a site of persecution, where Christians who refused to renounce their faith were tortured with boiling spring water. The Shimabara Rebellion of 1637–1638 was fought at the foot of the mountain. In the twentieth century Unzen became an international resort.
Unzen Disaster Memorial Hall
雲仙岳災害記念館Unzen-dake saigai kinenkanA museum in Shimabara on the 1990–1995 eruption, known as Gamadas Dome.
- 殉教碑junkyōhi
A memorial in Unzen Jigoku to the Christians martyred there.
- 島原城Shimabara-jō
The castle of Shimabara town, overlooked by Mayuyama and Unzen.
History
701
Traditional founding of Manmyō-ji on Unzen.
1627–1631
Christians are tortured and killed at Unzen Jigoku.
1792
Collapse of Mayuyama and tsunami kill about 15,000 people.
1934
Unzen is designated one of Japan's first national parks.
1990–1995
Eruption builds Heisei-shinzan; the 3 June 1991 pyroclastic flow kills 43.
2009
The Shimabara Peninsula becomes a UNESCO Global Geopark.
Through the seasons
Spring
Azaleas bloom around Nita-tōge and Fugendake from late April to May.
Summer
Unzen Onsen, at about 700 m, stays cooler than Nagasaki; a traditional summer retreat.
Autumn
Maple colours around Nita-tōge in early November.
Winter
Rime ice (muhyō) coats the trees around Nita-tōge and Fugendake on cold mornings.
Routes and trails
Nita-tōge – Fugendake circuit
From Nita-tōge (or by ropeway to Myōkendake) via Kunimi-wakare to Fugendake and back via the Fūketsu cave, about 2–3 hours; moderate.
Unzen Jigoku walk
Paths through the fumarole fields of Unzen Onsen, about 30–60 minutes; easy.
Mizunashi valley and memorial park
Visit the buried houses and viewpoints over the dome at the Shimabara foot; by car or bus.
Practical notes
- Unzen Onsen is about 1.5 hours by bus from Isahaya station; Shimabara is on the Shimabara Railway.
- Heisei-shinzan and the upper Mizunashi valley are permanently closed; follow signs on Fugendake trails.
- Unzen is monitored as an active volcano by the Japan Meteorological Agency.
Frequently asked questions
Can Heisei-shinzan be climbed?
No. The lava dome is unstable and lies inside a permanent restricted zone. Hikers climb neighbouring Fugendake, from where the dome can be seen at close range.
What happened on 3 June 1991?
A pyroclastic flow from the growing lava dome swept down the Mizunashi valley and killed 43 people, including journalists, firefighters and the volcanologists Katia and Maurice Krafft and Harry Glicken.
What was the 1792 disaster?
After an eruption of Fugendake, an earthquake caused the collapse of Mayuyama above Shimabara; the landslide entered the Ariake Sea and generated a tsunami that struck Shimabara and the coast of Higo, killing about 15,000 people. It is remembered as "Shimabara taihen, Higo meiwaku".
How long does the Fugendake hike take?
From Nita-tōge by ropeway to Myōkendake, then about 1–1.5 hours to Fugendake and back to the pass; around 3 hours without the ropeway.
Related
Sources
- 1.日本の主な山岳標高 (opens in a new tab) — 国土地理院 (Geospatial Information Authority of Japan)
- 2.雲仙天草国立公園 (opens in a new tab) — 環境省 (Ministry of the Environment)
- 3.火山登山者向けの情報提供ページ（雲仙岳） (opens in a new tab) — 気象庁 (Japan Meteorological Agency)
- 4.長崎県ホームページ (opens in a new tab) — 長崎県 (Nagasaki Prefecture)