is a

volcanic A volcano is a rupture in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface. On Earth, volcanoes are most often found where tectonic plates a ...

island to the south of Japan in northernmost

Micronesia Micronesia (, ) is a subregion of Oceania, consisting of about 2,000 small islands in the western Pacific Ocean. It has a close shared cultural history with three other island regions: the Philippines to the west, Polynesia to the east, and ...

. It is the southernmost and most isolated inhabited island of the Izus, which are politically and administratively part of Japan but geographically not part of the Japanese archipelago. The islands border the northeast Philippine Sea and lie immediately north of the

Bonin Islands The Bonin Islands, also known as the , are an archipelago of over 30 subtropical and tropical islands, some directly south of Tokyo, Japan and northwest of Guam. The name "Bonin Islands" comes from the Japanese word ''bunin'' (an archaic read ...

, which are also governed by Japan. Nussbaum, Louis-Frédéric. (2005)
"''Izu Shotō'',"
''Japan Encyclopedia,'' p. 412. The island is approximately south of Tokyo and south of

Hachijō-jima is a volcanic Japanese island in the Philippine Sea. It is about south of the special wards of Tokyo. It is part of the Izu archipelago and within the Fuji-Hakone-Izu National Park. Its only municipality is Hachijō. On 1 March 2018, its p ...

. The village of Aogashima administers the island under

Hachijō Subprefecture is a subprefecture of Tokyo Metropolis, Japan. The organization of government belongs to the Tokyo Metropolitan Government Bureau Of General Affairs. Hachijō includes the following towns and villages in the Izu Islands: * Hachijō (town on H ...

Tokyo Metropolis Tokyo (; ja, 東京, , ), officially the Tokyo Metropolis ( ja, 東京都, label=none, ), is the capital and largest city of Japan. Formerly known as Edo, its metropolitan area () is the most populous in the world, with an estimated 37.468 ...

. The island's area is and, , its population is 170. Aogashima is also within the boundaries 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 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 volcano eruption. When large volumes of magma are erupted over a short time, structural support for the rock above the magma chamber is ...

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 , abbreviated JMA, is an agency of the Ministry of Land, Infrastructure, Transport and Tourism. It is charged with gathering and providing results for the public in Japan that are obtained from data based on daily scientific observation an ...

, the last eruption of Aogashima was during a four-year period from 1781–1785. It is located along the

Izu–Bonin–Mariana Arc The Izu–Bonin–Mariana (IBM) arc system is a tectonic plate convergent boundary in Micronesia. The IBM arc system extends over 2800 km south from Tokyo, Japan, to beyond Guam, and includes the Izu Islands, the Bonin Islands, and the Marian ...

. 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 (IBA) by BirdLife International because it supports populations of Japanese woodpigeons, Pleske's grasshopper warblers,

Ijima's leaf-warbler Ijima's leaf warbler (''Phylloscopus ijimae'') (also known as Izu leaf warbler, Ijima's willow warbler or Ijima's warbler) is a species of Old World warbler in the family Phylloscopidae. The species is native to Japan, where it has been designate ...

s 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 or is the period between 1603 and 1867 in the history of Japan, when Japan was under the rule of the Tokugawa shogunate and the country's 300 regional '' daimyo''. Emerging from the chaos of the Sengoku period, the Edo period was characte ...

records kept at Hachijō-jima, which recorded volcanic activity in 1652, and from 1670 to 1680. An

earthquake swarm In seismology, an earthquake swarm is a sequence of seismic events occurring in a local area within a relatively short period. The time span used to define a swarm varies, but may be days, months, or years. Such an energy release is different f ...

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 flows 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.

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