USC College Professor Emeritus Keiiti Aki, a geophysicist known for his pioneering research on the fundamentals of geophysics and seismology, died May 17 on La R�union, a French island in the Indian Ocean. He was 75.
According to e-mails from his wife, geophysicist Valerie Ferrazzini, and colleague Thomas Staudacher of the Observatoire volcanologique du Piton de la Fournaise, Aki fell in the street coming home from the grocery store Friday, May 13.
The next day, he checked into the hospital, and doctors unsuccessfully performed surgery to stop uncontrolled bleeding in the brain. Aki went into a coma and passed away a few days later. Aki was buried in the cemetery of the town of Le Tampon on La R�union.
In a career spanning 50 years, Aki published more than 200 papers in seismology and co-authored the cardinal textbook of his field, “Quantitative Seismology.” He is considered one of the leading seismologists of his era, as well as one of the most widely cited authors in earthquake science.
“Kei’s influence in geophysics was broad. He studied a tremendous variety of scientific problems and made substantial contributions in almost all of them,” said University Professor Thomas Jordan, the W.M. Keck Foundation Chair in Geological Sciences and director of the Southern California Earthquake Center, a National Science Foundation Science and Technology Center founded by Aki.
Headquartered at USC College, SCEC is an international consortium of more than 40 institutions that undertake integrative, collaborative research on earthquakes and seismic hazards.
“Kei Aki was a gentle giant � gentle among friends and colleagues, and a giant within the field of seismology,” said USC’s Tom Henyey, professor of earth sciences and SCEC deputy director.
“As the founder and first director of SCEC � today the premier academic earthquake research organization in the country � Kei put USC earth sciences on the map,” said Henyey, who knew him for more than 40 years.
News of Aki’s death saddened colleagues at USC and around the world, according to John McRaney, associate director of SCEC at USC College and a close friend of Aki.
“Most of us are just in shock,” said McRaney, who had exchanged e-mails with Aki as recently as late April. “He wrote that he planned to live another quarter century and that our paths would cross many times again.”
McRaney described Aki as a very private man who “was a premier teacher and mentor. He had the uncanny ability to recognize the strengths in his students and draw out their best work.”
Aki mentored more than 60 doctoral and postdoctoral students who now occupy academic and government research positions in the U.S., Japan, China, France, Brazil, New Zealand, England and Mexico.
Born in 1930 in Yokohama, Japan, Aki grew up in post-WWII Japan, an experience that shaped the man he was to become, McRaney said.
Aki earned his Ph.D. from the Geophysical Institute of the University of Tokyo in 1958, by which time his publications on fundamental issues in earthquake science had already brought him to the attention of leading U.S. geoscientists such as Charles Richter, the inventor of the Richter magnitude scale.
In the late 1950s and early ’60s, Aki worked as a postdoctoral fellow with one of the most esteemed geophysicists in the United States � Frank Press, then at Caltech, who later served as president of the National Academy of Sciences and as science adviser to President Jimmy Carter.
Aki returned to a faculty position at the University of Tokyo for a number of years before Press, who by then had been recruited to start a modern, physics-based geology program at the Massachusetts Institute of Technology, convinced him to join the MIT faculty. Aki was Press’ first faculty hire, according to Henyey.
Aki taught at MIT for 18 years before moving to USC College in 1984, where he was the W.M. Keck Foundation Professor of Geological Sciences until his retirement in 2000.
In 1991, Aki was the founding director of SCEC and served as its director until 1996. “He envisioned SCEC as a center without walls. He wanted to create an open environment, where scientists could share their ideas and thoughts, and develop collaborations,” McRaney said.
“Aki wanted to understand what every wiggle on a seismogram represents,” Henyey said.
The seismic waves produced during an earthquake, and recorded by the wavering needle on a seismograph, contain information about the kind and magnitude of an earthquake. “Aki showed that the wiggles tell us not only about the earthquake itself, but about what’s inside the Earth,” Henyey said.
Among his many accomplishments, Aki developed a way to analyze seismic waves to infer more about the structure of the planet and the source of an earthquake.
Throughout his career, Aki searched for ways to extract new information from the data contained in seismograms. One special interest in the latter part of his career was the study of what earth scientists, borrowing from musicians, call the coda of a seismogram � “the wiggles that appear at the end of the seismogram.”
Beginning in 1995, Aki lived on the seismically active La R�union Island in the Indian Ocean, where he continued to investigate the complexities of seismic waves and the active Earth up until the time of his death.
Studying the active Piton de la Fournaise volcano of La R�union, he made progress in his work exploring how he could predict volcanic eruptions using primarily seismic methods. He was writing his autobiography and working on a new book on earthquake prediction when he died.
“There are what you can think of as the different notes � like in music � in the earth tremors preceding an eruption, so Kei was interested in trying to understand what these different tremors are telling us,” Henyey said.
In December 2004, Aki received the William Bowie Medal, the highest honor bestowed by the American Geophysical Union, for his “outstanding contributions to fundamental geophysics and for unselfish cooperation in research.”
In April, Aki was honored by the European Geosciences Union, which awarded him its top prize � the Beno Gutenberg Medal. The award citation called Aki “a pioneer in many fields of seismology” and recognized his outstanding ability as a teacher.
Aki pursued a range of interests in his research, which led to critical insights about the internal structure of the Earth, the sources of energy driving earthquakes and volcanic processes, predicting earthquake and ground motion, and the analysis of earthquake-associated hazards.
Aki was also honored for his leadership in the creation of the interdisciplinary SCEC, considered by some to be among his most important legacies to the field.
Among his many distinctions, Aki was a member of the U.S. National Academy of Sciences and a fellow of the American Academy of Arts and Sciences.
Aki is survived by his wife and four children: sons Shota of Weare, N.H., and Zenta of Redondo Beach, Calif., from his first marriage; and daughters Kajika and Uka of La R�union, from his marriage to Ferrazzini.
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