Fifth Presentation of the James B. Macelwane Award, April 20, 1966

Abstract

Don Anderson was born in Frederick, Maryland, thirty-three years ago. He took his Bachelor's degree at Rennselaer Polytechnic Institute in 1955. Between 1955 and 1958 he worked for Chevron Oil Company, served in the Air Force, and conducted research for the Arctic Institute of North America. He received his Ph.D. from Caltech in 1962, where he currently serves as Associate Professor of Geophysics. Don L. Anderson has utilized the range of modern observations concerning seismic body and surface waves, the free vibrations, and the loss characteristics of all these to re-evaluate and to revise interpretations of the elastic and anelastic structure of the Earth. He has analyzed recent observations of large artificial explosions to elucidate the complex events in the epicentral range 10°–40°, where he finds that a succession of triple-valued travel-time curves appears to occur. These curves are interpreted in terms of two regions of rapid increase in both velocity and density, one at the bottom of the Gutenberg low-speed zone at depth 300 km, the other at depth 600 km. These interpretations are consistent with the results from free-mode observations. The two levels of rapid changes may represent zones of phase change. In the lower mantle, the density increases very slowly relative to the rates in the earlier Earth models.