"1549.0"^^ . . "Mount Sempu in the northern arm of Sulawesi, Indonesia, contains a 3 km wide of caldera. A maar, called Kawah Masem, was formed in the southwest of the caldera and contains a crater lake. Sulfur deposits have been extracted from the maar since 1938. Historical records, however, are unknown from the volcano."@en . . . "Mount Sempu"@en .