The geography of Indonesia is dominated by volcanoes that are formed due to subduction zones between the Eurasian plate and the Indo-Australian plate. Some of the volcanoes are notable for their eruptions, for instance, Krakatau for its global effects in 1883, Lake Toba for its supervolcanic eruption estimated to have occurred 74,000 Before Present which was responsible for six years of volcanic winter, and Mount Tambora for the most violent eruption in recorded history in 1815.
Four peninsulas dominate the shape of Sulawesi island (formerly known as Celebes). The central part is high mountaineous area, but mostly non-volcanic. Active volcanoes are found in the northern peninsula and continuously stretches to the north to Sangihe Islands. The Sangihe Islands marks the border with Philippines.