Establishment of Japan's Seismic Building Codes

Following the 1923 Kanto Earthquake that killed over 100,000 people, Japan revised its Urban Building Law to require seismic resistance in structural design. Engineer Toshikata Sano's lateral force method, proposed in his 1916 doctoral thesis, became the basis for requiring buildings to withstand horizontal forces equal to 10 percent of their weight. This seismic coefficient of 0.1 derived from dividing the estimated 0.3g peak ground acceleration during the Kanto quake by a safety factor of three, establishing a framework that influenced seismic codes worldwide.