Keiiti Aki


Keiiti Aki (安芸 敬一, Aki Keiichi, March 3, 1930 – May 17, 2005) was a Japanese-American professor of Geophysics at the Massachusetts Institute of Technology (MIT), and then at the University of Southern California (USC), seismologist, author and mentor. He and Paul G. Richards coauthored "Quantitative Seismology: theory and methods".[2]

Keiiti Aki
Keiiti Aki.gif
BornMarch 3, 1930
DiedMay 17, 2005(2005-05-17) (aged 75)
Alma materUniversity of Tokyo
Scientific career
University of Southern California
Doctoral studentsShamita Das
InfluencedThomas H. Jordan[1]


Aki was born in Yokohama, Japan. He received his bachelor's degree in 1952 and doctoral degree in 1958, both from the University of Tokyo. Until 1960, he conducted research at that university's Earthquake Research Institute. He then did post-doctoral research at the Caltech Seismological Laboratory, where he worked with Frank Press.[3]

Press invited Aki to join him at MIT in 1966. This second visit to the United States coincided with the 1966 Parkfield earthquake, noteworthy for its so-called coda waves, reverberations of seismic energy due to multiple scattering from subsurface inhomogeneities. Aki "developed a passion for using those waves to investigate Earth," according to Bill Ellsworth, Aki's former student who was later head of the USGS seismology group. "He came from Japan as a statistically oriented seismologist, but he was not afraid to transform himself."[3]

Aki was very active in his field and was the president or chair of many organizations. He was the president of Seismological Section of the AGU, president of the Seismological Society of America, and Chair of the NAS Committee on Seismology. He was instrumental in the creation of the Southern California Earthquake Center, headquartered at the University of Southern California, in 1991, he having moved to USC from MIT in 1984.

In 1995, Aki moved to the seismically active island Réunion, east of Madagascar in the Indian Ocean, where he continued to work until his death there in 2005.[4] He sustained an injury to his brain from a fall while walking in the street on May 13; he fell into a coma and died on May 17. He left behind two sons (Shota and Zenta) and two daughters (Kajika and Uka).

Honors receivedEdit

Selected publicationsEdit

  • Aki, Keiiti (1966). "4. Generation and propagation of G waves from the Niigata earthquake of June 14, 1964. Part 2. Estimation of earthquake moment, released energy and stress-strain drop from G wave spectrum" (PDF). Bulletin of the Earthquake Research Institute. 44: 73–88.
  • Aki, Keiti; Richards, Paul G. (2002). Quantitative seismology (2 ed.). University Science Books. ISBN 0-935702-96-2.
Preceded by
Southern California Earthquake Center Director
1991 – 1995
Succeeded by


  1. ^ Perlman, David (May 26, 2005). "Study sheds new light on Mammoth Mountain's age". The San Francisco Chronicle.
  2. ^ "Keiiti Aki | Japanese seismologist". Encyclopedia Britannica. Retrieved 2019-10-07.
  3. ^ a b "Keiiti Aki: Seismological Polymath"[permanent dead link] Geotimes (March 2005)
  4. ^ "In memoriam: Keiiti Aki" Archived 2011-05-30 at the Wayback Machine, USC Trojan Magazine (Autumn, 2005)
  5. ^ "Book of Members, 1780-2010: Chapter A" (PDF). American Academy of Arts and Sciences. Retrieved 6 April 2011.
  • Pearce, Jeremy (May 27, 2005). "Keiiti Aki, 75, Is Dead; Developed a Way to Measure the Strength of an Earthquake". The New York Times.
  • "Biographical Sketch for: Keiiti Aki" (PDF). Retrieved 2008-04-05.
  • AKI, Keiiti International Who's Who. accessed September 3, 2006.