is a

volcanic island Geologically, a volcanic island is an island of volcanic origin. The term high island can be used to distinguish such islands from low islands, which are formed from sedimentation or the uplifting of coral reefs (which have often formed ...

to the south of

Japan Japan is an island country in East Asia. Located in the Pacific Ocean off the northeast coast of the Asia, Asian mainland, it is bordered on the west by the Sea of Japan and extends from the Sea of Okhotsk in the north to the East China Sea ...

in northernmost

Micronesia Micronesia (, ) is a subregion of Oceania, consisting of approximately 2,000 small islands in the Northwestern Pacific Ocean. It has a close shared cultural history with three other island regions: Maritime Southeast Asia to the west, Poly ...

. It is the southernmost and most isolated inhabited island of the

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 Prefecture. The largest is Izu Ōshima, usually called simply Ōsh ...

. The islands border the northeast

Philippine Sea The Philippine Sea is a List of seas#Marginal seas by ocean, marginal sea of the Pacific Ocean, Western Pacific Ocean east of the list of islands of the Philippines, Philippine Archipelago (hence the name) and the List of seas#Largest seas ...

and lie north of the

Ogasawara Islands The Bonin Islands, also known as the , is a Japanese archipelago of over 30 subtropical and tropical islands located around SSE of Tokyo and northwest of Guam. The group as a whole has a total area of but only two of the islands are permanen ...

. Nussbaum, Louis-Frédéric. (2005)
"''Izu Shotō'',"
''Japan Encyclopedia,'' p. 412. The island lies approximately south of mainland Tokyo and south of

Hachijō-jima is a volcano, volcanic Islands of Japan, Japanese island in the Philippine Sea. It is about south of the special wards of Tokyo. It is part of the Izu Islands, Izu archipelago and within the Fuji-Hakone-Izu National Park. Its only municipalit ...

. The island is administered as the village of Aogashima, which is subordinate to the Hachijō Subprefecture, which itself is governed by the City of Tokyo. The island has an area of , and, , its population is a mere 170 people. This means that the village of Aogashima has the smallest population of any municipality in Japan. Aogashima is also part of the

Fuji-Hakone-Izu National Park is a national park in Yamanashi, Shizuoka, and Kanagawa Prefectures, and western Tokyo Metropolis, Japan. It consists of Mount Fuji, Fuji Five Lakes, Hakone, the Izu Peninsula, and the Izu Islands. Fuji-Hakone-Izu National Park covers . Rat ...

Geology

Aogashima is a complex

Quaternary The Quaternary ( ) is the current and most recent of the three periods of the Cenozoic Era in the geologic time scale of the International Commission on Stratigraphy (ICS), as well as the current and most recent of the twelve periods of the ...

volcanic island 3.5 km in length with a maximum width of 2.5 km, formed by the overlapping remnants of at least four submarine

caldera A caldera ( ) is a large cauldron-like hollow that forms shortly after the emptying of a magma chamber in a volcanic eruption. An eruption that ejects large volumes of magma over a short period of time can cause significant detriment to the str ...

s. The island is surrounded by very steep rugged cliffs of layered volcanic deposits. The southern coast also rises to a sharp ridge forming one edge of a caldera named with a diameter of 1.5 km. The caldera dominates the island, with one point on its southern ridge, with a height of , as the island's highest point. The caldera is occupied by a secondary cone named . Still considered a Class-C active volcano by the

Japan Meteorological Agency The Japan Meteorological Agency (JMA; ''気象庁, Kishō-chō'') is a division of the Ministry of Land, Infrastructure, Transport and Tourism dedicated to the Scientific, scientific observation and research of natural phenomena. Headquartered ...

, the last eruption of Aogashima was during a four-year period from 1781–1785. It is located along the Izu–Bonin–Mariana Arc. File:青ヶ島 2.jpg, Maruyama is the central cone in the caldera File:Aogasima maruyama.jpg, Maruyama in a close view

Important Bird Area

The island has been recognised as an

Important Bird Area An Important Bird and Biodiversity Area (IBA) is an area identified using an internationally agreed set of criteria as being globally important for the conservation of bird populations. IBA was developed and sites are identified by BirdLife Int ...

(IBA) by

BirdLife International BirdLife International is a global partnership of non-governmental organizations that strives to conserve birds and their habitats. BirdLife International's priorities include preventing extinction of bird species, identifying and safeguarding i ...

because it supports populations of Japanese woodpigeons,

Pleske's grasshopper warbler Styan's grasshopper warbler (''Helopsaltes pleskei''), also known as Pleske's grasshopper warbler and Taczanowski's warbler, is a species of Old World warbler in the family Locustellidae. It breeds in eastern Siberia to Korea, Kyushu and Izu Isl ...

s, Ijima's leaf-warblers and

Izu thrush The Izu thrush or Izu Islands thrush (''Turdus celaenops'') is a bird of the thrush family native to Japan. Behavior Feeding Izu thrushes eat small animals, such as earthworms and insects, and fruits, like cherries or mullberries. Breeding Th ...

es.

History

The history of human settlement on Aogashima is uncertain. Most of the people on Aogashima are Japanese. The island is mentioned in

Edo period The , also known as the , is the period between 1600 or 1603 and 1868 in the history of Japan, when the country was under the rule of the Tokugawa shogunate and some 300 regional ''daimyo'', or feudal lords. Emerging from the chaos of the Sengok ...

records kept at Hachijō-jima, which recorded volcanic activity in 1652, and from 1670 to 1680. An earthquake swarm in July 1780 was followed by steam rising from the lakes in the Ikenosawa Caldera. Further earthquakes in May 1781 led to an eruption. In April 1783,

lava flow Lava is molten or partially molten rock (magma) that has been expelled from the interior of a terrestrial planet (such as Earth) or a Natural satellite, moon onto its surface. Lava may be erupted at a volcano or through a Fissure vent, fractu ...

s from the Maruyama cone resulted in the evacuation of all 63 households on the island. During a massive eruption in 1785, some 130–140 of the population of 327 islanders perished. There has been no significant volcanic activity since the 18th century.

References

External links

Aogashima Village Official Website

- Japan Meteorological Agency * - Japan Meteorological Agency

- Geological Survey of Japan * {{Authority control Izu Islands Active volcanoes Islands of Tokyo VEI-5 volcanoes Calderas of Japan Important Bird Areas of the Nanpo Islands

Geology

Important Bird Area

History

See also

References

External links