To evaluate the ability for seal intervals to retain fluids in underlying reservoirs, we performed diffraction analysis of the shallow intervals (above 200 m) imaged by high-resolution P-Cable seismic data. We isolated diffractions from the P-Cable data and analyzed diffraction strength across the section, and observed both narrow-linear and broad-sinuous zones of high diffractivity. We interpreted these broad regions to be a response to variable fluid composition saturation including hydrocarbons, which may have escaped from underlying reservoirs.