Obituary: Professor Kenji Ishihara (1934 - 2025)
To the International Society for Soil Mechanics and Geotechnical Engineering (ISSMGE),
The Japanese Geotechnical Society (JGS) is deeply saddened to announce the passing of Professor Kenji Ishihara on December 26, 2025, in Tokyo, Japan, at the age of 91. A former President of both our Society and the ISSMGE, Professor Ishihara was a world-renowned authority whose pioneering research and leadership fundamentally transformed the field of earthquake geotechnical engineering.
Professor Ishihara served as the President of the Japanese Geotechnical Society from 1996 to 1997. Throughout his career, he remained dedicated to the advancement of our flagship journal, Soils and Foundations, contributing numerous seminal papers and actively participating in its editorial and peer-review activities since its inception in 1960. Nationally, he led the development of seismic design codes and liquefaction countermeasure projects following major earthquakes in Japan. In 1977, he played a pivotal role in hosting the 7th International Conference on Soil Mechanics and Foundation Engineering in Tokyo, and subsequently chaired or served as a member of numerous research and investigative committees, as well as a director for international relations.
Professor Ishihara's impact on the international community was unparalleled. As the President of the ISSMGE (1997 - 2001), he represented over 70 member countries and fostered global scientific cooperation. His vision led to the establishment of TC4 (now TC203: Earthquake Geotechnical Engineering and Associated Problems), where he served as the inaugural Chairman for eight years. He was also the founding Chairman of the Asian Technical Committee No. 3 (ATC3), addressing geotechnical hazards across the Asian region. In recognition of his monumental contributions, the ISSMGE established the prestigious "Ishihara Lecture" in 2004, which is delivered at the opening of major international conferences to honor his memory.
Beyond his research, Professor Ishihara provided critical technical guidance on infrastructure projects worldwide. He was not only a brilliant scientist who authored foundational texts like Fundamentals of Soil Dynamics and Soil Behaviour in Earthquake Geotechnics, but also a mentor who inspired countless engineers. His academic achievements were recognized with the world's most prestigious honors, including the 33rd Rankine Lecture (1993), the 4th Terzaghi Lecture (1997), and the Japan Academy Prize (2000). Just days before his death, on December 15, 2025, he was awarded the International Lifetime Achievement Medal by the International Society for Soil Mechanics and Geotechnical Engineering (ISSMGE).
Please find an English translation of the official obituary by Prof. Ikuo Towhata, published in the monthly journal of the Japanese Geotechnical Society, detailing his extraordinary life and achievements.
https://www.jiban.or.jp/wp-content/uploads/2026/02/obitruary_Prof_Ishihara.pdf
The Japanese Geotechnical Society extends its deepest condolences to his family, friends, and the global geotechnical community.
Sincerely,
Ryosuke Uzuoka
President, The Japanese Geotechnical Society
Professor, Kyoto University
