 At the summit, there are four large craters which contain active fumarole fields.An eruption in 1772 caused the northeast flank to collapse producing a catastrophic debris avalanche that destroyed 40 villages and killed nearly 3,000 people.The eruption truncated the volcano into a broad shape with two peaks and a flat area 1.1 km wide with Alun-Alun crater in the middle, making the mountain appear as a twin volcano; one of the peaks is called Papandayan and the other Mount Puntang.