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
Turrialba Volcano Turrialba Volcano Turrialba Volcano is an active volcano in central Costa Rica that has been explosively eruptive in recent years including 2016 and in January, March and April 2017. Visitors used to be able to hike down into the main crater, but increased volcanic activity in 2014-17, resulting in large clouds of volcanic ash, has caused the surrounding Turrialba Volcano National Park to close. The stratovolcano is high and is about 45 minutes from the Atlantic slope town of Turrialba. The summit has three craters, the largest of which has a diameter of . Below the summit is a mountain