Adam Dziewonski (* 1936, in Ukraine, formerly Poland) is a US geophysicist who has made seminal contributions to the determination of the large-scale structure of the Earth's interior and the nature of earthquakes using seismological methods. He is the Frank B. Baird, Jr. Professor of Science at Harvard University. 1936 (MCMXXXVI) was a leap year starting on Wednesday (link will take you to calendar). ... Geophysics, the study of the earth by quantitative physical methods, especially by seismic reflection and refraction, gravity, magnetic, electrical, electromagnetic, and radioactivity methods. ... Earth cutaway from core to exosphere. ... Global earthquake epicenters, 1963–1998. ... Seismology (from the Greek seismos = earthquake and logos = word) is the scientific study of earthquakes and the propagation of elastic waves through the Earth. ... Harvard University (incorporated as The President and Fellows of Harvard College) is a private university in Cambridge, Massachusetts, USA and a member of the Ivy League. ...

Life and main scientific contributions

After having earned a Masters from the University of Warsaw, Poland (1960), and a Doctor of Technical Sciences from the Academy of Mines and Metallurgy, Cracow, Poland (1965) Dziewonski taught at the University of Texas, Austin for several years before settling at Harvard. University of Warsaw (Polish: ) is the largest university in Poland. ... The University of Texas System comprises fifteen educational institutions in Texas, of which nine are general academic universities, and six are health institutions. ...

In the 1960s and 1970s, Dziewonski and his collaborators laid the foundation to the understanding of tectonic plate motions by exploring convection currents in the Earth's mantle with radial maps of seismic property variations, based on measurements of seismic waves. These studies led to the development of the Preliminary Reference Earth Model (PREM) in collaboration with Don Anderson; PREM establishes an accurate radial model of the Earth for seismic velocities, attenuation, and density. The tectonic plates of the world were mapped in the second half of the 20th century. ... Convection in the most general terms refers to the internal movement of currents within fluids (i. ... Earth cutaway from core to exosphere. ... A seismic wave is a wave that travels through the Earth, often as the result of an earthquake or explosion. ... Don L. Anderson (* 5th March, 1933, in Frederick, Maryland, USA) is a US geophysicist who has made important contributions to the determination of the large-scale structure of the Earths interior, especially using seismological methods. ... Attenuation is the reduction in amplitude and intensity of a signal with respect to distance traveled through a medium. ... In physics, density is mass m per unit volume V. For the common case of a homogeneous substance, it is expressed as: where, in SI units: ρ (rho) is the density of the substance, measured in kg·m-3 m is the mass of the substance, measured in kg V is...

Since the 1980s he has led two original and powerful research efforts. He has extended the radial models to be fully three-dimensional, along the way mapping and interpreting four "Grand" structures. The four include two regions of higher-than-average wavespeed, inferred to be cold and sinking mantle, one under the western edge of the Americas and the other under southern Eurasia. The two other features are slower-than-average wavespeed, inferred to be hot and rising, under the middle of the Pacific Ocean and Africa.

His other research direction has determined the orientation and magnitude of the deformation for most of the significant earthquakes that have been well-recorded. These results are known as the Harvard CMTs (centroid moment tensor solutions) and are continued today at Lamont-Doherty Earth Observatory by Goran Ekstrom as the Global CMT Project. The moment magnitude scale was introduced in 1979 by Tom Hanks and Hiroo Kanamori as a successor to the Richter scale and is used by seismologists to compare the energy released by earthquakes. ... Lamont-Doherty Earth Observatory is a world-class research institution specializing in earth sciences and part of Columbia University. ...

Dziewonski has received numerous honours and awards for his scientific achievements, among them the Gold Medal of Ettore Majorana Foundation and Centre for Scientific Culture (1999), Medal of the Seismological Society of America (2000), the Crafoord Prize of the Royal Swedish Academy of Sciences (1998), and the Bowie Medal of the American Geophysical Union (2002). He is also a member of the National Academy of Science. The Crafoord Prize was established in 1980 by Holger Crafoord, the inventor of the artificial kidney, and his wife Anna-Greta Crafoord. ... The Royal Swedish Academy of Sciences or , founded in 1739 by King Frederick I, is one of the Royal Academies in Sweden. ... The American Geophysical Union (or AGU) is a nonprofit organization of geophysicists, consisting (as of 2006) of over 49,000 members from over 140 countries. ... President Harding and the National Academy of Sciences at the White House, Washington, DC, April 1921 The National Academy of Sciences (NAS) is a corporation in the United States whose members serve pro bono as advisers to the nation on science, engineering, and medicine. ...

Important publication

• A. M. Dziewonski, D. L. Anderson: Preliminary reference Earth model. Physics of the Earth and Planetary Interiors 25, S.297–356 (1981)

External links

• Dziewonski's webpage at Harvard
• Global Centroid Moment Tensor project
• Citation upon receiving Bowie Medal