Bonin Islands Pacific Plate is subducting under the Philippine Sea Plate, which creates an oceanic trench to the east of the islands: the Bonin Trench. The crust of the Ogasawara Islands was formed by volcanic activity when subduction began 45–50 million years ago, and is composed mostly of an andesitic volcanic rock called boninite, which is rich in magnesium oxide, chromium, and silicon dioxide. The Ogasawara Islands may represent the exposed parts of an ophiolite that has not yet been emplaced on oceanic crust. The rocks of the Volcano Islands are much younger; Iwo Jima is a dormant volcano characterized by rapid
History of the Marshall Islands Empire had primarily economic interests in Micronesia. The Japanese interests were in land. Despite the Marshalls' small area and few resources, the absorption of the territory by Japan would to some extent alleviate Japan's problem of an increasing population with a diminishing amount of available land to house it. During its years of colonial rule, Japan moved more than 1,000 Japanese to the Marshall Islands although they never outnumbered the indigenous peoples as they did in the Mariana Islands and Palau. The Japanese enlarged administration and appointed local leaders, which weakened the authority of local traditional leaders. Japan also tried