Don L. Anderson, the Eleanor and John R. McMillan Professor of Geophysics, Emeritus, passed away on December 2, 2014. He was 81 years old.
Anderson's work helped advance our understanding of the composition, structure, and dynamics of Earth and Earth-like planets. He was a pioneer in the use of seismic anisotropy—variations in the velocities of seismic waves as they move at different angles through materials—to study Earth's interior, which allowed him to help discover and explain the boundaries of the planet's mantle.
In 1981, Anderson codeveloped, with geophysicist Adam Dziewonski, the preliminary reference Earth model (PREM), a one-dimensional model representing the average properties of Earth, including seismic velocities, attenuation, and density, as a function of planetary radius. PREM continues to be the most widely used standard model of Earth. Anderson, a former president (1988-1990) of the American Geophysical Union, is the author of the textbook, Theory of the Earth, a 1989 reference on the origin, composition, and evolution of Earth's interior. A completely updated version, New Theory of the Earth, was published in 2007.
Born in Frederick, Maryland, on March 5, 1933, the son of a schoolteacher and an electrician, Anderson received his BS in geology and geophysics from Rensselaer Polytechnic University in 1955. He worked for Chevron Oil Company from 1955 to 1956, the Air Force Cambridge Research Center from 1956 to 1958, and the Arctic Institute of North America from 1958 to 1960.
His service with the Air Force took him to Greenland, where his job was to determine how thick the ice had to be to support aircraft that were in trouble. "The Air Force wanted their pilots to land disabled planes on the sea ice, but the conventional wisdom at the time was that they would break through the ice and the crew would freeze to death," Anderson recalled in a 2001 oral history. Anderson and his colleagues found that, in fact, aircraft can land very easily on ice that is not very thick: "Even if the ice won't support the plane while it's sitting there, it will allow a plane to taxi long enough for the pilots to get out and then the plane can sink through the ice, or the wheels can poke through the ice. Our job was to study ice strength, and whether you could determine how strong it was before you landed so you would know where to land." The project continued after Anderson entered graduate school at Caltech (MS '59, PhD '62), where he studied geophysics and mathematics.
Upon his graduation from Caltech, Anderson was hired as a research fellow; he became an assistant professor in 1963, associate professor in 1964, and professor in 1968. Anderson was the Eleanor and John R. McMillan Professor from 1989 until his retirement in 2002.
From 1967 to 1989, Anderson was director of Caltech's Seismological Laboratory.
A fellow of the American Academy of Arts and Sciences, the National Academy of Sciences, and the American Philosophical Society, Anderson was also the recipient of the Emil Wiechert Medal of the German Geophysical Society, the Arthur L. Day Medal of the Geological Society of America, the Gold Medal of the Royal Astronomical Society, the William Bowie Medal of the American Geophysical Union, and the Crafoord Prize at the Royal Swedish Academy of Sciences.
In 1998, Anderson was awarded the National Medal of Science and was cited for his "immeasurable influence on the advancement of earth sciences over the past three decades nationally and internationally."
A full obituary will be posted at a later date.