Douze and Laster (1979) considered the problem of identifying the mode of propagating isotropic seismic noise by the characteristics of the cross-spectrum between two geophones. They noted that the cross-spectrum is purely real and 'no apparent phase velocities can be obtained from the data'. Their statement is clearly in error, since in a field measurement, all quantities in the equation can be measured except velocity. To my knowledge this result was first derived and used in seismic noise studies by Aki (1957, 1965). The technique was extended by Asten (1976, 1978) to allow phase velocities of two simultaneously propagating Rayleigh modes to be estimated. Henstridge (1979) formalized and extended the theoretical basis of the method. -from Author The Broken Hill Proprietary Co., G.P.O. Box 1383, Brisbane, Qld, Australia.
|Number of pages||1|
|Publication status||Published - 1983|