Features of Chichijima Island
Consists of over 30 islands and manned islands are only Chichijima Island and Hahajima Island
Ogasawara Islands are islands located approximately 1000 kilometers south from Tokyo consisting of approximately 30 large and small islands and scattered approximately 400 kilometers north and south in the vast waters over the Pacific Ocean. The national park areas are Mukojima Islands, Chichijima Islands, Hahajima Islands, Kitaiwo Island and Nishinoshima Island of the Iwo Islands. The islands where public lives are Chichijima Island and Hahajima Island only and approximately 2,500 people are living their lives. The climate belongs to the subtropical maritime climate and it is temperate and humid throughout the four seasons. Annual average temperature is approximately 23 degrees and average temperature in winter is approximately 18 degrees, thereby annual range in temperature is low. Annual rainfall is approximately 1300 mm and it is slightly less than mainland (Tokyo).
Origins of the island
Approximately 48 million years ago, the Pacific Plate began to subduct below the Philippine Sea Plate, and the Chichijima Islands and Mukojima Islands were born by submarine volcanic activities caused by magma under the plate. Then, the location where the magma occurred moved to deeper west side and Hahajima islands was born approximately 44 million years ago. Even now, the subduction of the plate continues, and volcanic activity is observed in Iwo Islands. In November 2013, an eruption occurred in southeast of Nishinoshima Island, a new land became integrated with Nishinoshima Island and Nishinoshima Island has expanded to approximately 9 times the area before the eruption.
World rare geography and geology such as pillow lava, boninite and submerged Karst, etc.
Boninite (unmanned rock) which was generated at the time of the birth of Chichijima Islands is a special kind of andesite that generates only during the birth of island arc. It is exposed in the largest scale in the world and is preserved in good condition. The mineral ore gathered on shore by the weathering of this rock is called Uguisu sand. In Minamijima Island, there are submerged karst sank in the sea where the geography formed by erosion and weathering of limestone. Besides, there are sea cliff which is bluff of height of 200m, pillow lava made of eruption of submarine volcano, etc. and it is a treasury of rare geography and geology.
Biological evolution on ocean islands was evaluated and registered as Japan’s fourth UNESCO World Natural Heritage
Since Ogasawara is an ocean island that has never landed on the continent until now, creatures flew the sky, they were carried by ocean currents, winds and birds and accidentally reached the island. As a result of achieving their own evolution, unique nature was formed. This was evaluated as conforming to the evaluation criteria of the World Natural Heritage “Ecosystem” and was registered as Japan’s fourth UNESCO World Natural Heritage in June 2011. Although it is a small island, its proportion of endemic species is high, valuable evidence of evolution process on land shellfish and plants is remained is highly evaluated.
http://www.soumu.metro.tokyo.jp/07ogasawara/nature/wnhogasawara.html（外部サイト）
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Chichijima Island
- Features of Chichijima Island
- History of Chichijima Island
- Wildlife of Chichijima Island
- Sightseeing on Chichijima Island
- Accessing Chichijima Island