Permalink : http://hdl.handle.net/2115/36728

Fractures developed in the atrio of Komagatake Volcano, Hokkaido, are classified into three main types. 1) 1929 fractures along the atrio margin, 2) 1929 concentric fractures, and 3) the 1942 major fissure. The former two fractures were formed by settling and compaction due to welding as well as settling of the 1929 pyroclastic deposits, respectively. These fractures were strongly controlled by the older topography. The 1942 major fissure extending across the atrio for 1.6 km in NW-SE, was initially produced by doming due to the excess magma pressure, and enlarged by explosions and subsequent collapse of the wall.