Volcano in Japan
Japan is famous as one of the volocanic countries in the world. In Japan, there are many "active volcanoes" including famous localities for signtseeing spots or hot springs. The term of "active volcano" means a volvano which has erupted during last 10,000 years or continues remarkable fumarolic activity.
Volcanoes range in the topographic high places forming the mountains on the land or chains of islands in the ocean. This volcanic chain is called "volcanic front" which means the first occurence of volcanoes from the trench toward the back-arc side.
Most volcanoes in Japan are formed from magma originated in the mantle wedge. This magma is thought to be generated by the subduction of the oceanic plate. Subducted oceanic crust brings water in the forms of water of crystallization or hydrate. Water makes the melting temperature of mantle peridotite lower than "dry" mantle. On the other hand, intrusion of the cold slub into the mantle induces the convection of the hot astenosphere into mantle wedge. This produces hot condition under the volcanic arc.
For further information of each volcano in Japan, please check " Quaternary Volcanoes in Japan " which is other database produced by Geological Survey of Japan (Geological Survey of Japan, AIST).