is a volcanic island

Island

An island or isle is any piece of sub-continental land that is surrounded by water. Very small islands such as emergent land features on atolls can be called islets, cays or keys. An island in a river or lake may be called an eyot , or holm...

 in the Izu Islands

Izu Islands

The are a group of volcanic islands stretching south and east from the Izu Peninsula of Honshū, Japan. Administratively, they form two towns and six villages; all part of Tokyo. The largest is Izu Ōshima, usually called simply Ōshima....

 and administered by the Tokyo

Tokyo

, ; officially , is one of the 47 prefectures of Japan. Tokyo is the capital of Japan, the center of the Greater Tokyo Area, and the largest metropolitan area of Japan. It is the seat of the Japanese government and the Imperial Palace, and the home of the Japanese Imperial Family...

 Metropolitan government, Japan

Japan

Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...

, lies about 100 km south of Tokyo, 22 km east of the Izu Peninsula

Izu Peninsula

The is a large mountainous peninsula with deeply indented coasts to the west of Tokyo on the Pacific coast of the island of Honshū, Japan. Formerly the eponymous Izu Province, Izu peninsula is now a part of Shizuoka Prefecture...

 and 36 km southwest of Bōsō Peninsula

Boso Peninsula

thumb|Locationthumb|Landsat image with high-resolution data from Space Shuttle is a peninsula in Chiba prefecture on Honshū, the largest island of Japan. It forms the eastern edge of Tokyo Bay, separating it from the Pacific Ocean....

. serves as the local government of the island. The town (municipality

Municipality

A municipality is essentially an urban administrative division having corporate status and usually powers of self-government. It can also be used to mean the governing body of a municipality. A municipality is a general-purpose administrative subdivision, as opposed to a special-purpose district...

) was formed in 1955 by the amalgamation of six separate villages (municipalities), which were:

1. Okada (north)
2. Moto (west)
3. Senzu (northeast)
4. Nomashi (west, south of Moto)
5. Sashiki (south, with Mabushi)
6. Habuminato (southeast)

Moto, which had been called Motomura (village) until then, became seat of the local government for the whole island as Motomachi (town).

Izu Ōshima, at 91.06 km² is the largest and closest of Tokyo's outlying islands, which also include the Ogasawara Islands.