Masubi is an active volcano on Jupiter's moon Io. It is located on Io's leading hemisphere at 49°36′S 56°11′W / 49.6°S 56.18°W[1] within a bright terrain region named Tarsus Regio. A volcanic plume has been observed at Masubi by various spacecraft starting with Voyager 1 in 1979, though it has not been persistent like similar Ionian volcanoes Amirani and Prometheus.[2] Masubi is also notable for having one of the largest active lava flows on Io, with an additional 240 km (150 mi) flow forming between 1999 and 2007.[3]