Anderson, Don L. (earth scientist)

(1933- ) American Geophysicist

The structure of the deeper parts of the Earth cannot be viewed from the surface and therefore must be imaged using geophysical techniques. The best probes of this region are seismic waves. The seismic waves are generated at the earthquake foci, pass through the Earth, and return to the surface where they are recorded by seismographs. The greater the spacing between the earthquake and seismograph, the deeper the waves will probe the Earth. By studying minute changes in travel times of these waves and the relative travel times among waves, composition and even temperature of the deep subsurface can be determined. By performing a 3-D image analysis of these data, the structure of the deep interior of the Earth may be determined similar to how a CAT scan is used on the human body. CAT scanning of the Earth is called seismic tomography, and its main pioneer is Don L. Anderson.

Don Anderson demonstrating geophysical relations at the California Institute of Technology in Pasadena

Don Anderson demonstrating geophysical relations at the California Institute of Technology in Pasadena

Through seismic tomography, Don Anderson has shown a richly complex structure in the upper mantle and the lower crust with patterns of hot and not-so-hot areas. This work is summarized in his paper “Slabs, Hot Spots, Cratons and Mantle Convection Revealed from Residual Seismic Tomography.” As a result of this seismic tomography, Anderson has also proposed a theory that contrasts with previous notions that the internal engine of the Earth is like a pot on the stove with deeply derived heat sources driving convection cells that move the plates and cause earthquakes and volcanoes. Instead, he proposes that the surface features of the Earth may exert significant control on mantle convection and related processes as described in the paper “The Inside of Earth: Deep Earth Science from the Top Down.” Plate interactions and geometries may affect how the mantle moves.

These new ideas led to a reconsideration of how the Earth evolved through time both physically and chemically. Indeed, his new models have implications for how any planet evolves through time as described in the paper “A Tale of Two Planets.” Anderson developed new models to explain the location of volcanoes based upon crustal stress fields. He uses types and amount of volatiles (gases) in lava to propose that the generation of virtually all magma is very shallow rather than the deep source hypothesis that still prevails with many scientists. Even the classically deep “hot spots” like Hawaii may be from a shallow source. Indeed, Anderson has nearly single-handedly redefined the function and importance of the as-thenosphere, lithosphere, and his “perisphere.” His top-down (rather than the classic bottom-up) approach to the Earth, both physically and chemically, is revolutionary and establishes Anderson as a true pioneer in the Earth sciences.

Even without all of the fame of his work in seismic tomography, Don Anderson has a distinguished career studying seismology of the Earth. Many of his studies establish new benchmarks in the processes by which seismic waves travel through the Earth and what information can be gleaned from their study.

Don L. Anderson was born on March 5, 1933, in Frederick, Maryland, but he was raised in Baltimore. He always enjoyed science and rock collecting, so when he went to college at Rensse-laer Polytechnic Institute, New York, he majored in geology and geophysics and graduated with a bachelor of science degree in 1955. From 1955 to 1956, he worked as a geophysicist for Chevron Oil Co. From 1956 to 1958, he worked as a geo-physicist in the U.S. Air Force Cambridge Research Center. In 1962, he earned a Ph.D. at the California Institute of Technology in geophysics and mathematics. From 1962 to 1963, he was a research fellow at the California Institute of Technology before becoming an assistant professor in 1963. He was promoted to associate professor in 1964 and finally to full professor in 1968. From 1967 to 1989, he directed the Seismological Laboratory at the California Institute of Technology before becoming the Eleanor and John R. McMillan Professor of geophysics in 1989, the position he holds today. During this time, he was a Cox Visiting Scholar at Stanford University, a Green Visiting Scholar at the University of California at San Diego, an H. Burr Steinbach Visiting Scholar at Woods Hole Oceanographic Institution in Massachusetts, and a Tuve Distinguished Visitor at the Carnegie Institution, Washington, D.C.

Don Anderson has had an extremely productive career publishing more than 200 articles in international journals and professional volumes. The list of honors and awards that he has received in recognition of his research contributions is staggering. Foremost among these awards is the National Medal of Science which President Bill Clinton bestowed on him in 1999. He received an honorary doctorate from Rensselaer Polytechnic Institute. In addition, he received the James B. Macelwane Award in 1966 and the Bowie Medal in 1991 both from American Geophysical Union, the Apollo Achievement Award in 1969 and the Distinguished Scientific Achievement Award in 1977 both from NASA, the Arthur L. Day Medal from the Geological Society of America in 1987, the Newcomb-Cleveland Prize from the American Association for the Advancement of Science in 1976, the Emil Wiechert Medal from the German Geophysical Society in 1976, the Gold Medal from the Royal Astronomical Society in 1988, and the Crafoord Prize from the Royal Swedish Academy of Science in 1998. He is a Fellow at the National Academy of Sciences and the American Academy of Arts and Sciences.

Anderson has served on many important committees at the National Academy of Sciences, National Research Council, NASA, National Science Foundation, American Geophysical Union (Fellow and president (1988-1990)), Geological Society of America, American Association for the Advancement of Science, Carnegie Institution of Washington, D.C., and several others. He has served in an editorship capacity for some of the top international journals including Journal of Geophysical Research, Tectonophysics, Geological Society of America Bulletin, and Journal of Geody-namics, to name a few. He was an evaluator of some of the top geophysical programs worldwide, including Princeton University, Harvard University, University of Chicago, Stanford University, University of California at Berkeley, and University of Paris, among others. Indeed, Don Anderson participated in many of the committees, review panels, and projects that truly shaped the current state of the Earth sciences.

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