Fundamental Study on the Terrain Effects of Mount-Hiji on Damages Caused by the Atomic Bomb Dropped in Hiroshima

At the event of the atomic bomb dropped in Hiroshima, Danbara district which is located behind Mount Hiji approximately 2.3 km distant from the center of explosion, suffered less damages than surrounding districts. This phenomenon is expressed by the word called as "shade of Mount Hiji" in Hiroshima. In this research, a basic experiment to verify the topographic effects of Mount Hiji on the shock wave of the atomic bomb was carried out. In this basic experiment, by using the shadowgraph method, behaviors of the shock wave passing a topographical model of isosceles triangle and Mount Hiji model. Pressure measurement behind the model was also conducted in the experiment. As a result of the experiment, basic information on the phenomenon in which the shock wave was shielded by Mount Hiji and did not reach much to Danbara district was obtained.