Katsutada Sezawa

{{Use dmy dates|date=November 2021}}

{{Short description|Japanese seismologist}}

{{Infobox Scientist

| name = Katsutada Sezawa

| native_name = 妹沢 克惟

| native_name_lang = ja

| image = Katsutada Sezawa in 1944.jpg

| caption =

| birth_date = 21 August 1895

| birth_place = Ishikawa Prefecture, Japan

| death_date = {{Death date and age|1944|04|23|1895|08|21|df=y}}

| death_place =

| residence =

| nationality = Japanese

| alma_mater = Tokyo Imperial University

| doctoral_advisor =

| doctoral_students =

| known_for = Theoretical study of seismic wave generation and propagation and others

| footnotes =

| prizes = Imperial Prize of the Japan Academy (1931)

| religion =

| field =

| work_institution = Earthquake Research Institute

}}

Katsutada Sezawa ({{Langx|ja|妹沢 克惟}}, 21 August 1895 – 23 April 1944{{Citation|author=高橋裕、藤井肇男 共著|title=近代日本土木人物事典: 国土を築いた人々|date=2013|url=|volume=|pages=|series=|edition=|publisher=鹿島出版会|doi=|isbn=978-4306094291|id=|ref=kindai-doboku|translator=|authorlink=}}) was a Japanese geophysicist (Seismologist).{{Cite web|last=日本人名大辞典+Plus|first=日本大百科全書(ニッポニカ),デジタル版|title=妹沢克惟とは|url=https://kotobank.jp/word/%E5%A6%B9%E6%B2%A2%E5%85%8B%E6%83%9F-1085146|access-date=13 July 2021|website=コトバンク|language=ja}} Sezawa's key work was on the mathematical aspects of wave transmission in media of different viscosities and the Sezawa wave mode of surface waves is named after him.

Sezawa was born in Ishikawa Prefecture where his father was a judge.{{Cite web|last=20世紀日本人名事典,367日誕生日大事典|title=妹沢 克惟とは|url=https://kotobank.jp/word/%E5%A6%B9%E6%B2%A2%20%E5%85%8B%E6%83%9F-1647815|access-date=13 July 2021|website=コトバンク|language=ja}} He graduated in 1921 from the Imperial University of Tokyo in shipbuilding and became a professor at the university in 1928. Sezawa became the director of the Earthquake Research Institute, University of Tokyo. His key work was on theoretical aspects of seismic wave transmission in different media. He was able to calculate differences in the structure of the earth based on seismic observations. He also predicted the existence of surface waves which are now termed as Sezawa waves.{{cite journal|author=Sezawa, K.|year=1927|title=On the Propagation of Rayleigh Waves on Plane and Spherical Surfaces|url=https://repository.dl.itc.u-tokyo.ac.jp/record/35079/files/ji0020003.pdf|journal=Bull. Earthquake Res. Inst. (Tokyo)|volume=2|pages=21–28}}{{cite journal|author=Sezawa, K.|year=1927|title=Dispersion of Elastic Waves Propagated on the Surface of Stratified Bodies and on Curved Surfaces|url=https://repository.dl.itc.u-tokyo.ac.jp/record/35067/files/ji0030001.pdf|journal=Bull. Earthquake Res. Inst. (Tokyo)|volume=3|pages=1–18}} He was awarded the Imperial Prize of the Japan Academy (1931).{{Cite web|title=授賞一覧｜日本学士院|url=https://www.japan-acad.go.jp/japanese/activities/jyusho/021to030.html#anker021|access-date=13 July 2021|website=www.japan-acad.go.jp}}