, or Parece Vela, is a coral reef, geologically an atoll, with two rocks enlarged with tetrapod-cement structures. It is administered by Japan with a total shoal area of and land area . Its dry land area is mostly made up by three concrete encasings and there is a stilt platform in the lagoon housing a research station. There is a third completely artificial tetrapod-cement islet.
is located on the Palau–Kyushu Ridge in the Philippine Sea, southeast of Okidaitōjima and west-southwest of South Iwo Jima in the Bonin Islands or south of Tokyo, Japan. is the southernmost part of Japan and the only Japanese territory south of the Tropic of Cancer.
Japan argues that is significant enough for it to claim a exclusive economic zone (EEZ) around it, but China, South Korea, and Taiwan dispute the Japanese EEZ, saying that the atoll does not meet the definition of an island under the United Nations Convention on the Law of the Sea.
History
The atoll may have been sighted first by Spanish sailor Bernardo de la Torre in 1543, although the first undisputed sighting was by Miguel López de Legazpi in 1565. Its first recorded name was Parece Vela (Spanish for "looks like a sail", alluding to the original appearance of the reef). This name has been retained in English as well, especially to designate the geological formations of the islets.
In 1789, Captain William Douglas arrived with the British ship Iphigenia and, in 1790, the place was named Douglas Reef (also spelled Douglass Reef). This name continues to appear in modern sources. In 1796, what was likely the reef was then re-discovered by the brig Nautilus, under the command of Captain Charles Bishop, and the name Nautilus Rocks has appeared in some sources.
The existence of the atoll might not have been known by the Japanese until 1888. In 1922 and 1925, the Japanese navy ship Manshu investigated the area. In 1931, confirming that no other countries had claimed the reefs, Japan declared it Japanese territory, placing it under the jurisdiction of the Tokyo Metropolis, classifying it as part of the Ogasawara Village, and naming it Okinotorishima, meaning "remote bird islands". English names derived from the Japanese include Okinotori coral reefs and Okinotori Islands.
During 1939 and 1941, a foundation was completed for a lighthouse and a meteorological observation site, but construction was interrupted by the outbreak of World War II. After Japan's defeat, the United States assumed sovereignty over the Ogasawara islands, and returned authority over the islands to Japan in 1968.
Between 1987 and 1993 the government of Tokyo and later the central government built steel breakwaters and concrete walls to stop the erosion of Okinotorishima, which today leaves only three of the five rocks that were present in 1939 above water; in 1988 the Japan Marine Science and Technology Center built a marine investigation facility which it has since maintained following typhoon damage. Funding for full repairs was finally allocated in early 2016. The facility also doubles as an EEZ observation post for the Maritime Bureau of the Ministry of Land, Infrastructure, Transport and Tourism, being equipped with radar and various other sensors to help monitor activity in the zone.
On March 16, 2007, a light beacon was installed by the Japan Coast Guard. The beacon is plotted on the hydrographic chart.
Geology
Geologically, the islets are a coral atoll, built on the Kyushu–Palau Ridge, the westernmost part of the Izu–Bonin–Mariana Arc system. The name Parece Vela Basin has been given to the extinct back-arc basin that lies immediately to the east (the northern half of this back-arc basin is known as the Shikoku Basin). This back-arc basin was formed by seafloor spreading between the late Oligocene and Miocene. The Parece Vela Basin contains the longest megamullion in the world. The original Spanish name of the islets is normally used for the geological formations, hence, Parece Vela megamullion, Parece Vela ridge, Parece Vela Rift or Parece Vela basin.
The waters around the reefs are potentially rich in oil and other mineral and fisheries resources and it lies in an area of potential military significance. At high tide, one area of the reef is , roughly the size of a twin bed, and pokes just out of the ocean. The other is , the size of a small bedroom, and rises , about twice as high. The entire reef consists of approximately , most of which is submerged even at low tide.
The area has three tiny individual islets: Higashi-Kojima (東小島, "Eastern Islet") Kita-Kojima (北小島, "Northern Islet"), nevertheless rather in the "West" Minami-Kojima (南小島, "Southern Islet")