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No. 112: Jul-Aug 1997

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The Kind Of Fault You Like To Find

Earthquakes are concentrated along the boundaries between tectonic plates where oceanic plates dive under continental plates. Stresses naturally accumulate during such slow-motion collisions. The result: plenty of quakes. Mechanically, this model is very appealing, but there are puzzling exceptions. There are sections along plate boundaries obviously in collision where no earthquakes at all occur to relieve stresses. Quakes are felt on either side of these segments, but all is serene inside. These segments are termed "seismic gaps." They may stretch for hundreds of kilometers.

Theory insists that all seismic gaps must eventually be filled in. After all, the rocks can take only so much stress. Theory may be wrong because at least ten seismic gaps seem to be permanent. Something unexplained is transpiring beneath the surface that allows oceanic plates to slide quietly down under the continents and deep into the mantle.

One such permanent seismic gap is especially embarrassing to geophysicists. It stands out prominently on earthquake maps of the very active Peruvian coast. When the immense quake of 1974 shook this coastline, this gap was unperturbed. Neither did the many aftershocks violate this charmed region. Not believing in subterranean magic, some geophysicists confidently (and very loudly) predicted this reluctant gap would soon yield. After 23 years it is still there!

(Penvenne, Laura Jean; "When It's Better to Build on the Fault," New Scien tist, p. 14, January 11, 1997.)

From Science Frontiers #112, JUL-AUG 1997. 1997-2000 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