Nishinoshima, part of the Ogasawara Islands, has grown through volcanic eruptions since 2013. 

On Oct. 19, the Japan Coast Guard (JCG) announced that it appears Japan’s territorial waters will expand by about 70 square kilometers and its exclusive economic zone (EEZ) by about 50 square kilometers as a result of the island’s enlargement. Starting from the end of October, the JCG will conduct a detailed survey of the seacoast and seafloor and create a “nautical chart’ that indicates the sea depth and the starting point of Japan’s territorial waters.

According to the JCG, a new island appeared after an eruption on the seafloor about 500 meters southeast from the original Nishinoshima island in November 2013. The lava flowed down from the crater and solidified to merge with the original island. As a result, Nishinoshima expanded northward, southward, and eastward. As of September 2016, Nishinoshima has a total area of 2.68 square kilometers, 12 times its size before the eruptions. Based on estimates from aerial inspections, Japan’s territorial waters will expand by about 70 square kilometers mainly in the three directions.