U.S. Geological Survey, Menlo Park, CA.
THE DISCOVERY OF THE EARTH - The Quest to Understand the Interior of our Planet
This lecture summarizes the fascinating intellectual journey that led to "The Discovery of the Earth", that is, to understanding how the Earth works, and what it looks like inside. Early views of the Earth were limited by the distance that could be explored by a single individual or small community. The development of seafaring societies led to the discovery of a vast curved world. At 200 B.C. a prominent Greek scientist, Eratosthenes, made the first accurate measurement of the size of the Earth. Experience showed that our planet could both sustain and destroy life: entire cities were destroyed by terrifying earthquakes (Sodom and Gomorrah, 1,900 B.C.) or violent volcanic eruptions (Pompeii, 79 A.D.). These disasters were believed to be due to angry gods or forces deep within the Earth, such as powerful winds or Hell-fires. Such disasters also provided inspiration for the myths and fables that are part of many cultures.
The Earth's magnetic field has long been used to guide ships across the oceans. Some 400 years ago the multi-talented physician to Queen Elizabeth, William Gilbert, suggested that this magnetic field indicated that the interior of the Earth was a huge magnet. Later studies confirmed the existence of an iron core within the Earth that produces this strong magnetic field.
The invention of the seismograph some 120 years ago put to the test these early ideas about the interior of the Earth and the origin of earthquakes and volcanoes. This device measures small motions at the Earth's surface caused by natural disturbances, the most important of which are earthquakes. Seismographs are our best tool for painting a picture of the Earth's interior because earthquake waves travel deep within the Earth and form multiple echoes, much like depth sounders (sonar) used on ships. Today, many thousands of seismometers listen to the pulse of the Earth. Seismologists have used these seismic waves to study where and why earthquakes and volcanoes occur, and to find valuable natural resources such as oil and gas. "The Discovery of the Earth" charts the history of one of science's greatest achievements: understanding how the planet we live on works.
About Dr. Mooney
Education:
University of Wisconsin, Ph.D. in Geophysics, 1979
Cornell University, B.S. in Physics, 1973
Honors:
American Geophysical Union Fellow, 1996
Geological Society of America Fellow, 1987
Geological Society of London Fellow, 2000
Royal Astronomical Society Fellow, 2000)
George P. Woollard Award (Geological Society of America) for outstanding
contributions to geophysical studies, 1995
Gold Medal Award, Indian Geophysical Union, 2002
Positions Held:
Research Seismologist, USGS-Menlo Park, Ca., 1978-
Consulting Professor of Geophysics, Stanford University, 1984-
Visiting Professor Geophysics, University of Kiel, Germany, 1985
Chief of Seismology Section, USGS-Menlo Park, Ca., 1994-1997
Visiting Professor of Geophysics, Pierre et Marie Curie Univ., France,
1998
Visiting Professor of Geophysics, Univ. Louis Pasteur, Strasbourg, France,
2000
Brief summary of recent research and activities:
I have been engaged in studies of the internal properties of the Earth for the past 25 years. Most recently I have investigated the western USA and Alaska, especially regions prone to earthquakes. Internationally, I have engaged in field studies in western China, India, South America and the former Soviet Union. This experience has provided both a rich basis for my science, and a broad cultural understanding. I present more than two dozen invited lectures each year on topics related to the Earth Sciences for audiences ranging from the invited public to groups of specialists. I have lectured throughout the United States and internationally in more than twenty countries.
Societies:
Seismological Society of America
American Geophysical Union
Geological Society of America
Some recent publications:
Mooney, W.D., Continental Crust, in Encyclopedia of Physical Science and Technology, third edition, vol. 3, 635-647, 2002.
Artemieva, I. and Mooney, W.D.,
Thermal structure and evolution of Precambrian continental lithosphere:
A global study, J. Geophys. Res. 10616,387-16,414), 2001.
Mooney, W.D., Laske, G., and Masters, G., CRUST 5.1: A global crustal
model at 5° x 5°, J. Geophys. Res. 103, 727-747, 1998.
