Moveout Stretch Implications for AVO

The Zoeppritz equations for AVO, and their various approximations, apply strictly to a single isolated interface between two half-spaces. In practice this is almost always not the case, and effects known as AVO tuning are observed due to the apparent change in the time-thickness of beds on recorded traces with offset. While NMO or migration should equalise these time thicknesses across all offsets, the tuning effects are maintained by wavelet stretch. This stretch cannot be meaningfully avoided by 'non-stretch' processing, which simply corresponds to the isolated reflector paradigm. Meaningful AVO analysis, can, however, be achieved by effectively equalising the wavelet across all traces.