Adam Dziewonski
Encyclopedia
Adam Marian Dziewoński is a Polish-American 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
.
, Poland (1960), and a Doctorate of Technical Sciences from the Academy of Mines and Metallurgy, Cracow, Poland (1965) Dziewonski taught at the University of Texas at Dallas for several years before settling at Harvard.
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
.
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 large-scale regions of slower-than-average wavespeed, inferred to be hot and rising superplumes, located at the bottom of the mantle 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.
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), the Harry Fielding Reid Medal of the Seismological Society of America (1999), the Crafoord Prize
of the Royal Swedish Academy of Sciences (1998), and the Bowie Medal of the American Geophysical Union
(2002). In 1995 he was also elected a member of the United States National Academy of Sciences
.
Structure of the Earth
The interior structure of the Earth, similar to the outer, is layered. These layers can be defined by either their chemical or their rheological properties. The Earth has an outer silicate solid crust, a highly viscous mantle, a liquid outer core that is much less viscous than the mantle, and a...
and the nature of earthquakes using seismological
Seismology
Seismology is the scientific study of earthquakes and the propagation of elastic waves through the Earth or through other planet-like bodies. The field also includes studies of earthquake effects, such as tsunamis as well as diverse seismic sources such as volcanic, tectonic, oceanic,...
methods. He is the Frank B. Baird, Jr. Professor of Science at Harvard University
Harvard University
Harvard University is a private Ivy League university located in Cambridge, Massachusetts, United States, established in 1636 by the Massachusetts legislature. Harvard is the oldest institution of higher learning in the United States and the first corporation chartered in the country...
.
Life and main scientific contributions
After having earned a Masters from the University of WarsawUniversity of Warsaw
The University of Warsaw is the largest university in Poland and one of the most prestigious, ranked as best Polish university in 2010 and 2011...
, Poland (1960), and a Doctorate of Technical Sciences from the Academy of Mines and Metallurgy, Cracow, Poland (1965) Dziewonski taught at the University of Texas at Dallas for several years before settling at Harvard.
In the 1960s and 1970s, Dziewonski and his collaborators laid the foundation to the understanding of tectonic plate motions
Plate tectonics
Plate tectonics is a scientific theory that describes the large scale motions of Earth's lithosphere...
by exploring convection
Convection
Convection is the movement of molecules within fluids and rheids. It cannot take place in solids, since neither bulk current flows nor significant diffusion can take place in solids....
currents in the Earth's mantle
Mantle (geology)
The mantle is a part of a terrestrial planet or other rocky body large enough to have differentiation by density. The interior of the Earth, similar to the other terrestrial planets, is chemically divided into layers. The mantle is a highly viscous layer between the crust and the outer core....
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
Don L. Anderson
Don Lynn Anderson is an American geophysicist who has made important contributions to the determination of the large-scale structure of the Earth's interior, especially using seismological methods. He is Eleanor and John R. McMillan Professor emeritus of geophysics at the California Institute of...
; PREM establishes an accurate radial model of the Earth for seismic velocities, attenuation
Attenuation
In physics, attenuation is the gradual loss in intensity of any kind of flux through a medium. For instance, sunlight is attenuated by dark glasses, X-rays are attenuated by lead, and light and sound are attenuated by water.In electrical engineering and telecommunications, attenuation affects the...
, and density
Density
The mass density or density of a material is defined as its mass per unit volume. The symbol most often used for density is ρ . In some cases , density is also defined as its weight per unit volume; although, this quantity is more properly called specific weight...
.
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 large-scale regions of slower-than-average wavespeed, inferred to be hot and rising superplumes, located at the bottom of the mantle under the middle of the Pacific Ocean and Africa.
His other research direction has determined the orientation and magnitude
Moment magnitude scale
The moment magnitude scale is used by seismologists to measure the size of earthquakes in terms of the energy released. The magnitude is based on the seismic moment of the earthquake, which is equal to the rigidity of the Earth multiplied by the average amount of slip on the fault and the size of...
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
Lamont-Doherty Earth Observatory
The Lamont–Doherty Earth Observatory is a research unit of Columbia University located on a campus in Palisades, N.Y., north of Manhattan on the Hudson River.- History :...
by Goran Ekstrom as the Global CMT Project.
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
Ettore Majorana Foundation and Centre for Scientific Culture
Ettore Majorana Foundation and Centre for Scientific Culture is an organization based in Sicily, Italy. The President of EMFCSC is Prof. Antonino Zichichi. It sponsors the International School of Subnuclear Physics whose Director is Prof...
(1999), the Harry Fielding Reid Medal of the Seismological Society of America (1999), the Crafoord Prize
Crafoord Prize
The Crafoord Prize is an annual science prize established in 1980 by Holger Crafoord, a Swedish industrialist, and his wife Anna-Greta Crafoord...
of the Royal Swedish Academy of Sciences (1998), and the Bowie Medal of the American Geophysical Union
American Geophysical Union
The American Geophysical Union is a nonprofit organization of geophysicists, consisting of over 50,000 members from over 135 countries. AGU's activities are focused on the organization and dissemination of scientific information in the interdisciplinary and international field of geophysics...
(2002). In 1995 he was also elected a member of the United States National Academy of Sciences
United States National Academy of Sciences
The National Academy of Sciences is a corporation in the United States whose members serve pro bono as "advisers to the nation on science, engineering, and medicine." As a national academy, new members of the organization are elected annually by current members, based on their distinguished and...
.
Important publication
- A. M. Dziewonski, D. L. Anderson: Preliminary reference Earth model. Physics of the Earth and Planetary Interiors 25, S.297–356 (1981)