Seismic factors for structural design of buildings relating to geological ground condition were recently prescribed by Building Code in Japan. The map in the text shows the reduction coefficient to be multiplied to the basic seismic factor, 0.2 in every prefecture in Japan. The table indicated the reduction coeficient for each kind of structure (Wooden bldg. Steel bldg. Reinforced-concrete bldg. and Masonry bldg. from the left to the right column) and of geological ground condition (from the 1st. to the 4th).
