Natal basin

Sorikmarapi is a highly vegetated stratovolcano on Sumatra island, Indonesia. It has a 600 m wide of crater lake at the summit and some sulfur deposits. A small parasitic crater, called Danau Merah, is found at the upper southeast flank of the mountain and several solfatara fields at the eastern flank. During the 19th and 20th century, small phreatic eruptions occurred.