English: Aerial view, looking east, of Aniakchak caldera, one of the most spectacular volcanoes on the Alaska Peninsula. Formed during a catastrophic ash-flow producing eruption about 3,400 years ago, Aniakchak caldera is about 10 km (6 mi) across and averages 500 m (1,640 ft) in depth. Voluminous postcaldera eruptive activity has produced a wide variety of volcanic landforms and deposits within the caldera. The volcano is located in Aniakchak National Monument and Preserve, Alaska, which is administered by the National Park Service.