Fusakichi Omori

Fusakichi Omori was a Japanese seismologist who discovered the mathematical pattern now known as Omori's law, describing how the frequency of aftershocks following a major earthquake decreases roughly in proportion to the reciprocal of the time elapsed since the main shock. In 1899 Omori described a horizontal recording pendulum seismograph of his own design, later called the Omori seismometer, a modified version of which, the Bosch-Omori seismograph, remained in widespread use around the world until after the Second World War. Omori was among the first researchers to study how earthquakes affect structures by using shaking tables to compare experimental results against measurements taken from actual earthquakes, an early contribution to the field of earthquake engineering. Omori conducted extensive field investigations of major earthquakes internationally, including spending roughly 80 days studying damage and fault traces after the 1906 San Francisco earthquake, and he served as the second chair of seismology at Tokyo Imperial University and as president of Japan's Imperial Earthquake Investigation Committee.