Kookoon: Inner Earth: Release Information
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Release Date: 03.08.1999
TT Catalogue No: 4429
Inner Earth - a seismosonic symphony
The earth moves.It changes its shape according to many different time scales, ranging from millions of years to milliseconds. There is not a single moment of rest. Huge convection cells inside the earth cause a continuous rearrangement of the plates we are living on. Earthquakes are one of the most spectacular and frightening expressions of these dynamics, as are volcanic eruptions. But there are also more subtle movements, such as mountain uplift or erosion.
The earth generates sound. Any time. Any minute. Any second. Not acoustically but seismically and outside the audible range. Seismic waves which are continuously recorded by hundreds of seismological observatories around the globe. Signals from earthquakes, volcanic eruptions, wind, ocean surf, traffic, or explosions, etc..
In seismology, those waves are used to obtain information about the structure of the earth and the processes which cause earthquakes. Most of what we know about the interior of the earth is known from seismic waves by exploring their structure mathematically. Seismic signals often contain a visual beauty. Individual wave packages echoing discontinuities deep inside our planet or dispersed surface waves telling us about the change of wave speed with depth.
How does the earth sound? Does the visual fascination of seismograms have an acoustical equivalence? Do surface waves sound differently from body waves? Do earthquake signals from California sound differently from ones from China? Do micro-earthquakes« signals sound differently from waves, which have propagated through the inner core?
These questions have puzzled us for many years. Nearly as long as our friendship, which began with the lectures in music theory at the University of Tübingen we jointly took in the early seventies. Kept alive over the years by the thoughts expressed in Joachim Ernst Behrend's Nada Brahma, The World Is Sound and the challenge of Pierre Schaeffer's Musique Concretè.
But the earth doesn't reveal its music easily. At least not in an obvious way, such as by simply shifting the frequency contents of seismograms into the audible range. The results are - mildly put - disappointing. It is audible but it doesnÕt sound like anything. In technical terms, this is caused by the fact that simply increasing the pitch shortens the signal.
We have spent many nights in the studio trying to get around this problem, using many different methods of shifting, converting, and transposing the sounds to make them audible. Mostly we explored dead end roads. The analysis of the waves and the formants finally provided one of the technical keys to the sounds you hear on this record. Now we were about to create the instruments for ...
... the sound of the earth. As a result, what you are listening to on this
CD is all composed completely out of natural seismic signals. Signals from
earthquakes, microseism, as well as of volcanic origin. Sound fragments discovered
within the many hours of signals which we have explored. Rearranged and recomposed,
but without any additional instruments.
We feel especially rewarded by the encouragement of Joachim Ernst Berendt.
We acknowledge the use of seismogram material from the Seismological Central Observatory Gräfenberg in Erlangen, the PASSCAL data center of IRIS in Washington, and the GeoForschungsZentrum Potsdam. We owe personal thanks to Joachim Wassermann, Matthias Ohrnberger, and Winfried Hanka for their help with the data collection.
We would like to extend a very special thank-you to the people at Mark of the Unicorn, Cambridge, Mass. Their most excellent and innovative software contributed considerably to the sound of this project.