Ambiguity Between the Residual Geometrical Spreading and Scattering Attenuation

By introducing a residual geometrical spreading factor, a new model was proposed in recent papers of Morozov to improve the estimates of seismic Q, and some published seismic Q observations were reinterpreted under the framework of the new model. We found that in these papers the definitions about the residual geometrical spreading and seismic scattering attenuation were conceptually confusing, and physically impossible negative values of seismic Q may arise in the new model. We argue that the estimates of the residual geometrical spreading in the new model are influenced by seismic scattering. Thus, the correlation between the residual geometrical spreading and tectonic activity, and the observation of temporal variations of the residual geometrical spreading and apparent attenuation, as reported by Morozov, are not surprising.