Location East Asia Highest elevation 732.4 m (2,402.9 ft) Prefectures Hokkaidō Elevation 737 m Archipelago Japanese archipelago | Width 4 km (2.5 mi) Highest point Mount Era Subprefectures Oshima Subprefecture Area 9.73 km² | |
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Ōshima (大島) is an uninhabited island in the Sea of Japan, 50 kilometres (31 mi) to the west from Matsumae town and therefore the westernmost point in Hokkaidō. It is part of the town of Matsumae in Matsumae District, Oshima Subprefecture in Hokkaidō, Japan. To distinguish Ōshima from other islands with the same name, it is sometimes known as Oshima Ōshima (渡島大島) or Matsumae Ōshima (松前大島).
Contents
- Map of Oshima Island Ojima Matsumae Matsumae District Hokkaido Prefecture 049 1500 Japan
- History
- Flora and fauna
- References
Map of Oshima Island, Ojima, Matsumae, Matsumae District, Hokkaido Prefecture 049-1500, Japan
At 9.73 square kilometres (3.76 sq mi), Ōshima is the largest uninhabited island under Japanese sovereignty. The island is a double caldera with a scoria hill rising in the middle. It is the peak of two overlapping stratovolcanoes and their associated calderas, Mount Higashi and Mount Nishi. The highest peak, Mount Era (江良岳, Era-dake) at 737 metres (2,418 ft), is part of a triple volcano. The peak rises close to 2,000 metres (6,600 ft) from the sea floor. The island consists of mafic alkali and non-alkali volcanic rock, less than 18,000 years old.
On the south side of the island at Aidomari (北風泊, Aidomari), there are a lighthouse and a heliport operated by Japan Coast Guard.
Because of volcanic activity and nature conservation, landing on the island requires the approval of the Agency for Cultural Affairs.
History
Because of the island's isolation and volcanic activity there are almost no records of its past left behind. Mount Kanpo (寛保岳, Kanpo-dake) had a major eruption on 27 August 1741. The next day a tsunami struck the opposite shore and killed 1,467 people from Kumaishi to Matsumae.
Flora and fauna
Ōshima is the northern limit of the breeding grounds for the streaked shearwater and is part of the Matsumae-Yakoshi Prefectural Natural Park.