Farewells
Newcastle Herald
Monday June 20, 2005
KEIITI AKI: Arguably the greatest figure of seismology and earth science in the past 50 years has died after a fall in the street on the French island of La Reunion in the Indian Ocean. Aki, 75, was a trailblazer with the digital treatment of seismological observations that enabled him to determine the structure and internal dynamics of the Earth, as well as the properties of the sources of earthquakes. Aki's first and perhaps most important contribution was the introduction of a new way to measure the size of an earthquake more objectively. The Richter scale was until then the most commonly used measurement, but its calculation was not precise. In 1966, Aki introduced the seismic moment, a value calculated from geological and seismic measurements, which has become the most "appropriate single way to characterise" an earthquake's size. Aki was born in Japan and educated at the University of Tokyo but moved to work in the US in the 1960s. He retired in 2000 to study the active volcano Piton de la Fournaise on La Reunion to understand how seismic tremors could be used to predict volcanic eruptions. At the time of his death he was writing his autobiography and a book on earthquake predictions.
The Age
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