The United Nations' Commission on the Limits of the Continental Shelf has approved the addition of about 310,000 square kilometers to Japan's continental shelf, according to the government.
The term "continental shelf" describes a nation's oceanic territory including seabeds and everything lying below the water's surface, and generally extends out to the geolographical continental shelf or 200 nautical miles (about 370 kilometers) from shore, whichever is greater.
Continental shelves are significant, as a nation has the right to exploit natural resources, such as petroleum, found in its waters.
In 2008 the government submitted a request to the U.N. commission requesting about 740,000 square kilometers in the Pacific be declared part of Japan's continental shelf.
The approved addition of 310,000 square kilometers is spread over four areas, including one around Okinotorishima island, the nation's southernmost point of land, which is administratively part of Tokyo.
The U.N. commission postponed a conclusion on the Southern Kyushu-Palau Ridge Region, which is about 250,000 square kilometers south of Okinotorishima island, because China and South Korea have insisted that Okinotorishima is not an island but a mere rock and thus the region should not be recognized as part of the continental shelf.
The newly recognized limits of the continental shelf include most of the Shikoku Basin Region and the Ogasawara Plateau Region, and part of the Minami-Iwoto Region and the Southern Oki-Daito Ridge Region.
The total size of the four areas is comparable to about 80 per cent of Japan's land area, which is around 380,000 square kilometers. The government will soon revise documentation to stipulate the areas are included in Japan's continental shelf.
It is possible that natural resources within the newly claimed oceanic territory include rare metals and manganese. The government plans to conduct research to this end and explore the areas' seabeds.
The Minami-Torishima Region and the Mogi Seamount Region were not recognized within the nation's continental shelf because the U.N. commission judged the areas are not contiguous to Japanese territory and do not meet the requirements for an "extended continental shelf."
If a nation can provide proof of meeting the established U.N. requirements for an extended continental shelf, an area beyond the 200-nautical-mile border can further be declared part of the nation's continental shelf.