The two coalescing volcanoes forming the elongate, 9-km-long island of Anatahan in the central Mariana Islands are apparent in this aerial view from the south. The low point in the center of the island results in part from overlapping 2.3 x 5 km wide calderas, the largest in the Mariana Islands. The larger western caldera is 2.3 x 3 km wide and extends eastward from the 788-m-high summit of the western volcano (left). The volcano's first historical eruption in 2003 took place from a small crater within the 2-km-wide eastern caldera. Photo courtesy of U. S. Geological Survey, 1994.