Tau-p Filtering

Examination, evaluation and processing of seismic data in the two-dimensional τ-p domain offers many advantages over analysis and processing in the originally recorded X-t domain or other transformed domains. Since the slowness p (1) is the reciprocal the horizontal phase velocity, (2) represents the apparent angle of emergence at the surface, and (3) in a flat-layered earth it is also a constant conserved quantity (the ray parameter) along the raypath, we can readily address (1) antenna and array problems, (2) angle of incidence effects, and (3) problems (such as multiples) associated with the ray geometry. Examples of these applications include attenuation of ground roll, separation of P and S-waves where the angle of incidence defines the efficiency of mode conversion, and more efficient attenuation of multiples where they are exactly periodic in the τ-p domain.The present paper reviews and discusses some of these applications, with real data examples of each. It also discusses aspects of the τ-p transform relevant for such applications and an alteration of the forward transform that improves its filtering characteristics.