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
Japanese occupation of the Andaman Islands whilst the remainder either died of starvation or were killed by Burmese pirates. A rescue mission sent to the island after the end of the occupation found just twelve survivors, and over a hundred skeletons on the beach. In all, approximately 2,000 people in the Andamans are thought to have died as a result of the occupation, and at least 501 were tortured by the Japanese. The former figure represents 10% of the pre-war population of Port Blair. Casualties on the more sparsely-populated Nicobar islands were fewer, as the Japanese did not have a garrison there, although in 1943 they