The effects of attenuation on seismograms

Most seismic interpretation is performed with perfectly elastic models of the Earth's structure, and the potential ambiguities introduced by the neglect of attenuation are ignored. Using a modification of the reflectivity method, theoretical seismograms can be calculated for realistic attenuation structures by using complex velocity profiles. The effects of attenuation on recently proposed models of the low-velocity zone and the upper mantle are considered using this technique. A comparison between the results from models with and without attenuation suggest that the interpretation of observations for the attenuative Earth in terms of perfectly elastic models may give rise to apparently fine detail which would be smoothed out in an interpretation which allows for attenuation. It is likely that the major transitions in the upper mantle are sharper than has previously been suggested from amplitude studies.