Sakurajima (also spelled Sakurashima or Sakura-jima, 桜島 in Japanese) volcano in southern Kyushu is one of the most active volcanoes in the world, and one of the few that are at present in constant (persistant) activity. Its ongoing typical activity range from strong strombolian to large ash explosions every 4-24 hours. The volcano is located across Kagoshima Bay only 8 km east of the city of Kagoshima with a population of half a million. Sakurajima's eruptive history has been recorded since the 8th century. It has frequently deposited ash on Kagoshima, and due to its explosive potential, considered a very dangerous volcano and closely monitored. The largest historical eruptions of Sakurajima took place during 1471-76 and in 1914.

Sakurajima's present day volcano is a new volcanic cone inside the 17 x 23 km wide Aira caldera forming the northern half of Kagoshima Bay. The caldera formed around 22,000 years ago during a Plinian eruption that produced large pyroclastic flows.

Around 13,000 years ago, another smaller caldera, the so-called Wakamiko caldera was formed in the NE corner of the Aira caldera and was partially filled by volcanic cones. One of the new vents in this caldera eventually became present-day Sakura-jima located on the southern rim of Aira caldera. Sakurajima's early activity took place mainly at the Kita-dake summit cone until about 4850 years ago, after which its vent shifted to Minami-dake. The construction of Sakurajima formed a new island that was joined to the Osumi Peninsula during the major explosive and effusive eruption of 1914.