Izu Islands

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Map of the Izu Islands

The Izu Islands (伊豆諸島 Izu-shotō?) are a group of volcanic islands stretching south and east from the Izu Peninsula of Honshū, Japan.[1] Administratively, they form two towns and six villages; all part of Tokyo Prefecture. The largest is Izu Ōshima, usually called simply Ōshima.

Although traditionally referred to as the "Izu Seven" (伊豆七島 Izu Shichitō?), there are in fact more than a dozen islands and islets. Nine among them are currently inhabited.

Geography[edit]

Shikinejima from Kōzushima. Furthest: Ōshima; left: Toshima; right: Niijima; smallest: Jinai-tō.

The Izu islands stretch south-east from the Izu Peninsula on Honshu and cover an area of approximately 301.56 km2 (116.43 sq mi). There are nine populated islands with a total population of 24,645 people (as of 2009) spread over 296.56 km2 (114.50 sq mi). The largest of them is Izu Oshima (8,346 inhabitants, 91.06 km2 (35.16 sq mi)), the smallest Toshima (292 inhabitants, 4.12 km2 (1.59 sq mi).)[2] Of the inhabited islands, seven are traditionally referred to as the "Izu Seven": Oshima, Toshima, Niijima, Kozujima, Miyakejima, Hachijojima, and Mikurajima, though Shikinejima and Aogashima are sometimes included as well. [2]

Left: Walls built by exiles on Hachijojima
Right: A beach on Niijima

Each of the island has its unique character: Oshima is noted for its active volcano Mt Mihara and camellias, Hachijojima for its former penal colony, Mikurajima for dolphin watching, Niijima for its numerous beaches, Kozujima for its white sandy shores, Hachijojima for its well-preserved unique culture, and Miyakejima for the 2001 volcanic eruption. [2]

During the Edo period, Nii-jima, Miyake-jima, and Hachijō-jima served as places of exile for criminals.

The subtropical Ogasawara Islands, which are also administratively part of Tokyo, lie further to the south. They form a far-flung archipelago of over thirty (30) islands some 1,000 km due south of Tokyo.

Islands[edit]

Image Name
Kanji
Area
km²
Pop.
2007
Peak
m
Peak Name Coordinates
Landsat IzuOshima Island.jpg Izu Ōshima
伊豆大島
91.06 8472 764 Mihara 34°44′N 139°24′E / 34.733°N 139.400°E / 34.733; 139.400 (Izu-Ōshima)
Landsat Toshima Island.jpg To-shima
利島
4.12 304 508 Miyatsuka 34°31′N 139°17′E / 34.517°N 139.283°E / 34.517; 139.283 (Toshima)
Utone shima.jpg Udone-shima
鵜渡根島
0.4 - 1) 210   34°28′21″N 139°17′38″E / 34.47250°N 139.29389°E / 34.47250; 139.29389 (Udoneshima)
Landsat Shikinejima Island.jpg Nii-jima
(with Hanshima
and Jinai-tō)
新島
23.53 2420 432 Miyatsuka 34°22′N 139°16′E / 34.367°N 139.267°E / 34.367; 139.267 (Nii-jima)
Landsat Shikinejima Island.jpg Shikine-jima
式根島
3.9 600 109 Kambiki 34°19.5′N 139°13′E / 34.3250°N 139.217°E / 34.3250; 139.217 (Shikine-jima)
Landsat Kozushima Island.jpg Kōzu-shima
神津島
18.87 1914 574 Tenjō-zan 34°13′N 139°9′E / 34.217°N 139.150°E / 34.217; 139.150 (Kōzu-shima)
Landsat Miyakejima Island.jpg Miyake-jima
三宅島
55.48 2382 815 Oyama 34°5′N 139°32′E / 34.083°N 139.533°E / 34.083; 139.533 (Miyake-jima)
Ohnoharajima mlit1978.jpg Ōnohara-jima
大野原島
0.02 - 114 Koyasu 34°02′53″N 139°23′02″E / 34.04806°N 139.38389°E / 34.04806; 139.38389 (Ohnohara-jima)
Landsat Mikurajima Island.jpg Mikura-jima
御蔵島
20.58 313 851 Oyama 33°52.5′N 139°36′E / 33.8750°N 139.600°E / 33.8750; 139.600 (Mikura-jima)
Inambashima mlit.jpg Inamba-jima
藺灘波島
0.005 - 74   33°38′53″N 139°18′08″E / 33.64806°N 139.30222°E / 33.64806; 139.30222 (Inamba-jima)
Landsat Hachijojima Island.jpg Hachijō-jima
八丈島
69.54 8363 854 Nishiyama
(Hachijō-Fuji)
33°7′N 139°47′E / 33.117°N 139.783°E / 33.117; 139.783 (Hachijō-jima)
Hachojyo-kojima mlit1978.jpg Hachijō-kojima
八丈小島
3.08 - 2) 616.8 Taihei-zan 33°7′31″N 139°41′18″E / 33.12528°N 139.68833°E / 33.12528; 139.68833 (Hachijō-kojima)
Landsat Aogashima Island.jpg Aogashima
青ヶ島
5.98 192 423 Maruyama
(Ō-Toppu)
32°27′29″N 139°46′04″E / 32.45806°N 139.76778°E / 32.45806; 139.76778 (Aogashima)
Bayonaise Rocks mlit.jpg Bayonnaise Rocks
--- Myōjin-shō
ベヨネース列岩
0.01 - 9.9   31°53′14″N 139°55′03″E / 31.88722°N 139.91750°E / 31.88722; 139.91750 (Bayonnaise Rocks)
Smithisland milt.jpg Sumisu-tō
須美寿島
0.02 - 136   31°26′13″N 140°02′49″E / 31.43694°N 140.04694°E / 31.43694; 140.04694 (Sumisu-jima)
Tori-Shima Island of Izu-Islands Aerial photograph.jpg Tori-shima
鳥島
4.79 - 3) 394 Iō-zan 30°28′48″N 140°18′22″E / 30.48000°N 140.30611°E / 30.48000; 140.30611 (Torishima)
Soufuiwa.jpg Sōfu-iwa
孀婦岩
0.005 - 99   29°47′39″N 140°20′31″E / 29.79417°N 140.34194°E / 29.79417; 140.34194 (Sōfugan)

1) Udoneshima was inhabited during the Meiji era.
2) Uninhabited since 1969 (then population 31, with a peak of 513)
3) Torishima, the largest of the uninhabited islands, had a population of 150 until 1902, when all were killed by a volcanic eruption. Since then, the island has been uninhabited.

Administrative divisions[edit]

The Izu Islands are divided into two towns (Oshima and Hachijojima) and six villages (remaining inhabited islands.) Three subprefectures are formed above the municipalities as branch offices of the metropolitan government. [2]

All the islands (more than a dozen in total) lie within the Fuji-Hakone-Izu National Park.[2] The four southernmost islands are not administrated under any town or village in Hachijō Subprefecture, but are unincorporated areas. Torishima is now uninhabited but is an important bird refuge.

Deserted islands between Aogashima and Ogasawara Islands, namely Bayonaise Rocks (Beyonēzu Retsugan), Smith Island (Sumisu-tō), Torishima, and Lot's Wife (Sōfu-iwa) do not belong to any municipality, because both Hachijō Town and Aogashima Village claim administrative rights. They are directly controlled by Hachijō Subprefecture instead.

Demographics[edit]

Though the population on the Izu Islands has been dropping, the phase is less dramatic than on other isolated Japanese islands.[2]

Population changes[2]
Year Izu
Islands
Isolated
Japanese
islands
Japan
Total
1960 38,707 923,062 94,301,623
1970 32,539 736,712 104,665,171
1980 31,902 630,536 117,060,396
1990 30,032 546,505 123,611,167
2000 28,756 472,312 126,925,843
2005 26,242 422,712 127,767,994

Infrastructure[edit]

The primary industries are fisheries, agriculture, and, not the least, tourism. The most scenic spots on the islands are crowded with tourists during summers. Popular tourist activities include swimming, scuba diving, surfing, fishing, bird watching and trekking.[2]

Transportation between the islands, by cargo-passengers boats, jetfoils, and aircraft, is supported by harbours on all inhabited islands and five airports (small islands can be reached by helicopter).[2]

There are 5 airports, 15 harbors, and 19 fishing ports. Flights from Tokyo take 30 minutes, while boat takes 7–10 hours and jetfoils makes the route in about two hours. Transportation on the islands is considered important to the quality of life, why about 215 km (134 mi) of paved main roads serve a kind of vehicles.[2]

There was no electricity on the islands before 1953, but by 1962, 98% of the area receives electricity.[2]

Geology[edit]

The islands occupy the northern portion of the Izu-Bonin-Mariana Arc which extends to the Izu Peninsula and Mount Fuji on the Honshū mainland which are northern extensions of the Izu volcanic arc. The Izu arc ends there at a tectonic triple junction.

Volcanic activity is frequent in the area.[3] 31 people were killed when the research vessel Kaiyō Maru no 5 was destroyed during the 1953 eruption of Myōjin-shō. Volcanic activity, including the release of harmful gases, forced the evacuation of Miyake-jima in 2000. Residents were allowed to return permanently to the island in February 2005 but were required to carry gas masks in case of future volcanic emissions.[2]

2012 earthquake[edit]

On January 1, 2012 UTC 02:27 PM, an earthquake measuring 6.8 on the Richter scale hit the Izu Islands (31°24′58″N 138°09′18″E / 31.416°N 138.155°E / 31.416; 138.155).[4] There were no reports of casualties.[5]

To handle the various types of natural disasters threatening the region, including tsunamis, storm, floods, and volcanism, Tokyo metropolitan government has developed prevention and safety measures, including hazard maps and evacuation guidance, radios, signs, and a transport system for emergency supplies.[2]

Ecology[edit]

A chain of volcanic islands, the Izu Archipelago are oceanic islands that formed relatively recently (within a few million years) without any previous connection to mainland Japan. In contrast to isolated Pacific islands, such as Hawaii and the Galápagos, the Izu Islands are located near the mainland and have thus been frequently colonized by various species by overseas dispersal from the mainland or from adjacent islands. This make them interesting for the studies of ecological and evolutionary processes.[6]

Campanula (Bellflower) colonized the entire archipelago in a single event. Similarly, the Euhadra snails, endemic to Japan, populated the islands in a single event and all individuals on inhabited islands possess an identical haplotype. The Apodemus mice, on the other hand, colonized the islands from the mainland in two independent events.[6]

See also[edit]

References[edit]

  1. ^ Nussbaum, Louis-Frédéric. (2005). "Izu Shotō," Japan Encyclopedia, p. 412.
  2. ^ a b c d e f g h i j k l m Gotoh, H.; Maeno, Y.; Takezawa, T.; Murata, T.; Takahashi, N. (2010). "Infrastructure maintenance and disaster prevention measures on isolated Islands: the case of the Izu Islands near tokyo". In Favro, S.; Brebbia, C. A. Island Sustainability. WIT transactions on ecology and the environment (Vol. 130). WIT Press. ISBN 978-1-84564-434-5. 
  3. ^ Volcanoes of the Izu, Volcano and Mariana Islands
  4. ^ "Magnitude 6.8 - Izzu Islands, Japan Region". USGS. Retrieved January 2012. 
  5. ^ "7.0-magnitude quake hits Izu Islands, Japan region -- USGS". Philippine Star. January 1, 2012. Retrieved January 2012. 
  6. ^ a b Kuriyama, Takeo; Brandley, Matthew C.; Katayama, Akira; Mori, Akira; Honda, Masanao; Hasegawa, Masami (2011). "A time-calibrated phylogenetic approach to assessing the phylogeography, colonization history and phenotypic evolution of snakes in the Japanese Izu Islands". J. Biogeogr. 38: 259–271. doi:10.1111/j.1365-2699.2010.02403.x. 
  • Teikoku's Complete Atlas of Japan, Teikoku-Shoin Co., Ltd. Tokyo 1990, ISBN 4-8071-0004-1

Coordinates: 34°44′N 139°24′E / 34.733°N 139.400°E / 34.733; 139.400