Volcano Maps

　There are many active volcanoes in Japan. Because volcanic areas are blessed with numerous hot springs and scenic beauty, they are often developed as resort areas. However, a volcanic eruption would undoubtedly result in damage, so to prevent disasters, the Geospatial Information Authority of Japan(GSI) issues two types of volcano maps.

　The first type is the Volcanic Base Map. 40 of these maps(all are written in Japanese) have been completed so far(Existing the Volcanic Base Map). Contour lines on Volcanic Base Map show details of landforms. With a scale of 1:2,500 to 1:10,000, these maps have obverse only. Grid DEM (grid size: 10 m) have been issued for 26 of these volcanoes.

　The other type of volcano map is the Land Condition Map of Volcano, which has been issued for 23 volcanoes so far (Existing the Land Condition Map of Volcano). The obverse of these maps topographically depict classification of the volcanic material deposition (lava flows, pyroclastic flows, pyroclastic hills, debris avalanches, etc.) that was caused by previous volcanic activity. One Land Condition Map of Volcano shows one volcano. In addition, the backs of the maps provide a description and brief history of the volcano. While most of these Land Condition Map of Volcano are only in Japanese, some maps come with English legends.

　Differences between Volcanic Base Map and Land Condition Map of Volcano

　A volcano is a landform created when molten magma beneath the ground flows to the surface as lava, turning into pumice, scolia, volcanic ash, etc., then erupting with volcanic gas and building up in the area around the crater. When the ground surface rises or a landform is formed by phreatic explosion accompanied by a volcanic earthquake, it is also called a volcano even though no lava reaches the surface.
　Magma is underground molten rock that is primarily composed of silicon.