Doornbos, Durk J. Formerly, Institute for Geophysics, University of Oslo, Oslo, Norway.
- Earth among the planets
- Earth model concept
- Seismic structure
- Density structure
- Composition and state
- Geomagnetic dynamo
- Links to Primary Literature
- Additional Readings
All of the Earth beneath the land surface and the ocean bottom, including the crust, the mantle, and the core. The interior is not accessible to direct observation. Nevertheless, a rather detailed model has been constructed on the basis of measurements made at or above the surface. Measurements of gravity, the geomagnetic field, surface heat flow, and surface deformation can all be used to put constraints on the Earth model, but the most detailed information about the interior is provided by seismic measurements. To the nonspecialist, seismic methods are perhaps best known for their application to the oil exploration industry, where seismic data are used to map the subsurface structure of sedimentary basins. In the exploration of the Earth's interior, the seismic waves being analyzed are usually generated by earthquakes, and measurements are made of waves propagating through the interior of the body (body waves), waves propagating along the surface (surface waves), and standing waves bringing the whole Earth into a state of oscillation (free oscillations). Such measurements, when properly interpreted, provide information about seismic-wave velocities in the Earth. On the other hand, seismic-wave velocities can also be measured in laboratory experiments where rock samples are subjected to the high pressures and temperatures typical of conditions in the deep interior. Meteorites provide rock samples of materials that are probably abundant in the solar system. The comparison of laboratory and field measurements thus leads, by inference, to a model where the composition and temperature distribution can be specified to some extent. What emerges from these studies is a picture not only of the structure but also of the evolution and dynamics of the Earth's interior.
The content above is only an excerpt.
for your institution. Subscribe
To learn more about subscribing to AccessScience, or to request a no-risk trial of this award-winning scientific reference for your institution, fill in your information and a member of our Sales Team will contact you as soon as possible.
to your librarian. Recommend
Let your librarian know about the award-winning gateway to the most trustworthy and accurate scientific information.
AccessScience provides the most accurate and trustworthy scientific information available.
Recognized as an award-winning gateway to scientific knowledge, AccessScience is an amazing online resource that contains high-quality reference material written specifically for students. Contributors include more than 9000 highly qualified scientists and 43 Nobel Prize winners.
MORE THAN 8500 articles and Research Reviews covering all major scientific disciplines and encompassing the McGraw-Hill Encyclopedia of Science & Technology and McGraw-Hill Yearbook of Science & Technology
115,000-PLUS definitions from the McGraw-Hill Dictionary of Scientific and Technical Terms
3000 biographies of notable scientific figures
MORE THAN 19,000 downloadable images and animations illustrating key topics
ENGAGING VIDEOS highlighting the life and work of award-winning scientists
SUGGESTIONS FOR FURTHER STUDY and additional readings to guide students to deeper understanding and research
LINKS TO CITABLE LITERATURE help students expand their knowledge using primary sources of information