Geosciences

GEOSCIENCES BY PETER J. SMITH Department of Earth Sciences Open University Milton Keynes, U.K. " A new earthquake magnitude scale (Mm) based on the spectral amplitude of very-long-period Rayleigh waves can be determined from a single station and with no knowledge of focal mechanism or depth. Unlike classical magnitude scales, it bears a clear relationship to seismic movement—Mg—and is immune to interference saturation. EA. Okal, J. Talandier, “Mm: A variable-period mantle m

Peter Smith

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BY PETER J. SMITH
Department of Earth Sciences
Open University
Milton Keynes, U.K.

" A new earthquake magnitude scale (Mm) based on the spectral amplitude of very-long-period Rayleigh waves can be determined from a single station and with no knowledge of focal mechanism or depth. Unlike classical magnitude scales, it bears a clear relationship to seismic movement—Mg—and is immune to interference saturation.

EA. Okal, J. Talandier, “Mm: A variable-period mantle magnitude,” Journal of Geophysical Research, 94,4169-93, 10 April 1989. (Northwestern University,. Evanston, Ill.; Commissariat a l’Energie Atomique, Papeete, Tahiti, French Polynesia)

" Laser-ranging, doppler, and altimeter data from 14 near-earth satellites have been combined to obtain a “definitive” value of the earth’s geocentric gravitational coefficient. This value is 398600.4405 km^3 /sec^2 (including the mass of the atmosphere), with a standard deviation of only .001 km^3/sec^2.

J.C. Ries, R.I. Eanes, C. Huang, B.E. Schutz, et al., “Determination of the gravitational coefficient ...

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