Indonesia has the most volcanoes, with 76 volcanoes that have erupted within historical times. The Smithsonian Institution has 141 Indonesian entries in its volcano database; this includes volcanoes which have yet to erupt.
Seventy-six percent of the volcanoes in Indonesia are located along the Sunda Volcanic Arc. The arc is caused by the tectonic plate carrying the floor of the Indian Ocean slipping beneath the continental Asian plate. Among the volcanoes present in Indonesia is Krakatau; its eruption in 1883 resulted in 36,000 deaths. This was the second-deadliest eruption in Indonesian history. In 1815, Tambora erupted and killed 92,000 people, the deadliest eruption in both Indonesian history and world history.