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No. 103: Jan-Feb 1996

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A Subterranean Trombone

In 1992, while making seismic recordings near Java's Mount Semeru, a German scientific team noticed that the seismic waves were much more regular than one would expect from deep volcanic activity. Their recordings revealed a series of evenly spaced harmonic frequencies. They likened it to a musical instrument emitting a fundamental note accompanied by overtones. Sometimes, the fundamental tone would rise and fall, as if the mountain were playing a tune for them. The Germans, V. Schlindwein et al, postulated that the vibrations originated in a gas-filled cavity, presumably cylindrical -- something like an organ pipe -- capped at the top, with a pool of molten magma at the bottom. Volcanic vibrations resonated in this chamber and, as the magma pool rose and fell, so did the fundamental tone. Rather than a fixed organ pipe, it was a natural trombone! Unfortunately, the "earth music" was always in the infrasound range, 8 Hertz and less, and could not be heard by the researchers directly -- only their instruments could "listen."

(Schneider, David; "Country Music," Scientific American, 273:28, November 1995.)

Comments. There is no physical reason why such a subterranean trombone cannot play in the audible range. Such a mechanism might explain some of the mysterious hums heard in various localities, such as the Taos hum. (SF#88)

Many unusual natural sounds are cataloged in Chapter GS in our catalog: Earthquakes, Tides, Unidentified Sounds. Ordering information here.

Some animals can hear infrasound. Pigeons, for example, have special organs on their legs (of all places!) that respond to infrasound. Could pigeons and other birds use "musical mountains" for homing and other navigation feats?

From Science Frontiers #103, JAN-FEB 1996. 1996-2000 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