Jonathan Mark Ford , Roger Urgeles, Angelo Camerlenghi, Eulàlia Gràcia

Mass‐transport complexes (MTCs) are often characterised by small‐scale, discontinuous internal structure, such as slide blocks, rough interfaces, faults and truncated strata. Seismic images may not properly resolve such structure because seismic reflections are fundamentally limited in lateral resolution by the source bandwidth. The relatively weak seismic diffractions, instead, encode information on sub‐wavelength scale structure with superior illumination. In this paper, we compare diffraction imaging to conventional, full‐wavefield seismic imaging to characterise MTCs. We apply a seismic diffraction imaging workflow based on plane‐wave destruction filters to two 2‐D marine multi‐channel seismic profiles from the Gulf of Cadiz. We observe that MTCs generate a large amount of diffracted energy relative to the unfailed confining sediments. The diffraction images show that some of this energy is localised along existing discontinuities imaged by the full‐wavefield images. We demonstrate that, in combination with full‐wavefield images, diffraction images can be utilised to better discriminate the lateral extent of MTCs, particularly for thin bodies. We suggest that diffraction images may be a more physically correct alternative to commonly used seismic discontinuity attributes derived from full‐wavefield images. Finally, we outline an approach to utilise the out‐of‐plane diffractions generated by the 3‐D structure of MTCs, normally considered a nuisance in 2‐D seismic processing. We use a controlled synthetic test and a real data example to show that under certain conditions these out‐of‐plane diffractions might be used to constrain the minimum width of MTCs from single 2‐D seismic profiles.