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.
Sekincau is a volcano with two calderas, Belirang (2 kilometer wide) and Balak (2.5 kilometer wide), located in the south of Sumatra, Indonesia. A 300 meter wide of crater is found at the summit. Fumarole activities are found at the foot of calderas
