(b. Kagoshima, Japan, 14 June 1870; d. Tokyo, Japan, 1 January 1948)
Imamura was the second son of Akikiyo Imamura, a member of the Shimazu feudal clan. Among his ancestors was Eisei Imamura, a Dutch scholar and pioneer of veterinary science in Japan. The Meiji restoration of 1868 resulted in reducing most members of the feudal clans to near poverty, and Imamura was brought up in straitened circumstances. He early showed scholarly brilliance, and his family made great sacrifices to send him to Tokyo Imperial University. In 1894 he graduated in physics and became a university research assistant.
Two major earthquakes in 1891 and 1894 kindled in Imamura an intense desire to study seismology. He made important contributions to the scientific side of the subject but is noted above all for his concern with the human aspects. Dedicated to the problem of predicting earthquakes and mitigating their effects, he devoted his research principally, althrough not exclusively, to that end and was a member of numerous civil committees concerned with earthquakes.
In 1905 Imamura received the D.Sc. for work on the travel times of seismic waves. In 1923 he became a professor at Tokyo Imperial University and president of the Earthquake Investigation Committee of Japan. The following year he established at the Faculty of Science a department of seismology which has become world-famous. He also held posts at the imperial universities of Kyoto, Kyushu, and Tohoku. He was a founding member of the Japanese Academy of sciences and of the Earthquake Disaster Prevention Society of Japan, and was president of the Seismological Society of Japan.
In his more purely scientific work Imamura contributed to the development of the seismograph and of other instruments. He carried out special studies of tiltmeter records with a view to obtaining clues on impending earthquakes and was among the first to show systematic connections between ground tilting and earthquake occurrence. He made important related studies of earthquake foreshocks and aftershocks. Imamura carried out intensive field studies and analyses of macroseismic effects of earthquakes—effects observed in damaged areas—and drew up maps of expected earthquake intensities in specific regions of Japan.
Passionately convinced that his mission in life was to mitigate disastrous earthquake effects, Imamura held to this vision; his last paper on the subject was dictated form his deathbed. His efforts were on the widest scale, including scientific efforts to predict earthquakes, steps to have seismic areas of Japan finely surveyed, efforts to have buildings made earthquake-proof, measures to improve Japan’s fire-fighting facilities, and campaigns to educate the public on earthquake precautions. Examples of the detail to which Imamura went are his advocacy that kerosene lamps be abolished in Tokyo, his success in including a section on earthquakes in primary school syllabuses, and his public advocacy—to the extent of addressing a public meeting at a street corner at the age of seventy-seven. He was responsible for the reinforcement of the Imperial Diet Building in Tokyo, following his own experiments, and the erection of protective barriers against tsunami (seismic sea waves) along vulnerable coastlines. Knowledge of the Ainu language enabled him to determine the present locations of many obsolete Japanese place names and thereby to interpret more fully accounts of ancient earthquakes.
I. Original Works. Imamura’s principal publication is Theoretical and Applied Seismology, published in Japanese (Tokyo, 1936), trans. into English by D. Kennedy (Tokyo, 1937). This book incorporates his most important contributions to seismology, including summarized accounts of the content of many earlier papers published (in Japanese and English) in Japanese seismological journals.
II. Secondary Literature. References to Imamura’s more important findings and published papers are included in C. F. Richter, Elementary Seismology (San Francisco, 1958); and Takeo Matuzawa, study of Earthquakes (Tokyo, 1964). An obituary article is H. Kawasumi, in Jishin, 18 (May-Dec. 1948), 1-11, in Japanese.
K. E. Bullen