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.
The massive Mount Awu is the largest volcano in the Sangihe chain. Powerful eruptions occurred in 1711, 1812, 1856, 1892 and 1966 with devastating pyroclastic flows and lahars that have resulted in over 8,000 fatalities. A 4.5 km wide of crater is found at the summit and a deep valley forms a passageways for lahars, splitting the flanks from the crater.