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No. 93: May-Jun 1994

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The Giant Crystal At The Heart Of The Earth

Geophysicists have been forced to consider this possibility because of two anomalies:

  1. Seismic waves from earthquakes pass through the earth's core faster when they travel parallel to the earth's axis than when they travel in the plane of the equator. The transit time difference is 2-4 seconds. Apparently, the earth's core is not perfectly spherical or its properties are different in different directions.

  2. The natural vibration or "ringing" frequencies of the earth are "split," that is, instead of a series of single "tones" we detect a series of closely paired frequencies. This is symptomatic of a core that is anisotropic; that is, its properties are different in different directions.

J. Tromp, of Harvard, may have de-anomalized both sets of observations with a single theory:

"For the shape of the core alone to explain the observations, he says, the shape of the inner core would have to be very unrealistic. Instead, he claims that the inner core behaves like a giant asymmetric crystal, aligned with the Earth's axis so that seismic waves travel faster in that direction. Tromp's analysis fits neatly with suggestions that the inner core is made of a high-pressure phase of iron in which the atoms are close-packed in hexagons, because such a 'sigma' phase is anisotropic."

But, asks Tromp, how and why did the core material assume this crystalline character?

(Hecht, Jeff; "The Giant Crystal at the Heart of the Earth," New Scientist, p. 17, January 22, 1994.)

Comment. How does this big iron crystal jibe with the dynamo theory of the earth's magnetic field? Could Tromp's "giant asymmetric crystal" produce a permanent magnetic field, thereby forcing the supposed dynamo to play second magnetic fiddle?

From Science Frontiers #93, MAY-JUN 1994. 1994-2000 William R. Corliss

Science Frontiers Sourcebook Project Reviewed in:


  • "A sourcebook of unexplained phenomena is therefore a valuable addition to a collection of scientific literature. William R. Corliss has provided this in the past with his source books of scientific anomalies in several subjects, and now he has provided it for astronomy. He has done an excellent job of collecting and editing a large amount of material, taken in part from scientific journals and in part from scientific reporting in the popular or semi-scientific press." -- "The Mysterious Universe: A Handbook of Astronomical Anomalies", reviwed by Thomas Gold, Cornell University, in Icarus, vol.41, 1980

  • "An interesting, systematic presentation of unusual weather [..] This book is recommended for a general audience" --"Corliss, William R., Tornados, Dark Days, Anomalous Precipitation, and Related Weather Phenomena, Sourcebook Project, 1983.", revieweed in Choice, September 1983
  • "..the science is necessarily somewhat speculative, but Corliss's symthesis is based on reputable sources." -- "Corliss, William R. (Compiler). Lightning, Auroras, Nocturnal Lights, and Related Luminous Phenomena" reviwed by Joseph M. Moran, Univ. of Wisconsin in Science Books and Films, Sep/Oct 1983

  • "Before opening the book, I set certain standards that a volume which treads into dangerous grounds grounds like this must meet. The author scrupulously met, or even exceeded those standards. Each phenomenon is exhaustively documented, with references to scientific journals [..] and extensive quotations" -- "Book Review: The moon and planets: a catalog of astronomical anomalies", The Sourcebook Project, 1985., Corliss, W. R., Journal of the Royal Astronomical Society of Canada, Vol. 81, no. 1 (1987), p. 24., 02/1987