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Seismic or wavefield interferometry refers to a set of methods that synthesize\udwavefields between pairs of receivers, pairs of sources, or a source and a receiver,\udusing wavefields propagating from and to surrounding boundaries of sources\udand/or receivers. Starting from cross-correlations of ambient seismic noise recordings,\udwhich provide the signal between two receivers as if one of them had been an\udactive source, interferometric methods developed rapidly within the last decade,\udrevolutionizing the way in which seismic, acoustic, elastic, or electromagnetic\udwaves are used to image and monitor the interior of a medium. Only recently,\udan explicit link was found between the methods of source-receiver interferometry\ud(SRI) and seismic imaging, a technique widely used in seismic exploration to\udmap diffractors and reflectors in the subsurface, but also in more academic studies\udinvestigating, for example, deep crustal processes. This link is particularly\udinteresting because SRI, in contrast to classical imaging schemes, does not rely\udon the single-scattering assumption but accounts for all multiple-scattering effects\udin the medium. While first non-linear imaging schemes based on SRI have been\udproposed, the full potential of the method remains to be explored and a number\udof open questions concerning, for example, the role of non-physical energy in\udinterferometric wavefield estimates, require further investigation.\udThe aim of this thesis is to gain more insight into the method of source-receiver\udinterferometry in the context of wavefield construction and analysis in multiply\udscattering media, especially when theoretical requirements of the method (such\udas complete boundaries of sources and receivers, surrounding the medium of interest)\udare not met. First I analyse the single diffractor case using partial surface\udboundaries only. I find that only two out of eight terms of the SRI equation are\udrequired to construct a robust estimate of the scattered wavefield, and that one\udof these two terms is also used in seismic imaging. The other term provides a\udpseudo-physical estimate of the scattered wave; this is a new type of non-physical\udenergy that emulates the kinematics of a physically scattered wave. I then proceed\udto a multiple scattering scenario, using the pseudo-physical term to predict\udthe travel times and exact scattering paths of multiply diffracted waves. The presented\udalgorithm is purely data-driven and fully automated and, as a by-product,\udprovides a new tool to isolate primary diffracted waves from a complex multiply\uddiffracted wavefield. Finally, the concept is expanded to multiply reflecting\udmedia. In reflection seismic data, multiply reflected waves should be removed\udprior to migration in order to avoid artefacts in the seismic image. I demonstrate\udhow internal multiples can be estimated and attenuated using pseudo-physical\udenergy constructed from SRI. Moreover, an explicit link is derived between the\udinternal-multiple equation based on SRI and the internal-multiple equation derived\udfrom the inverse-scattering series (ISS), currently the most capable algorithm\udfor internal-multiple attenuation. Using the insight provided by the SRI\udapproach, I suggest an alternative equation that estimates internal multiples more\udeffciently compared to the current method.\udOverall, this thesis improves our understanding of how physical, non-physical, and\udpseudo-physical wavefields are constructed in SRI, how new information about\udmultiply scattered wavefields can be inferred, and how SRI relates to other methods\udof wavefield analysis, in particular seismic imaging and the ISS

Diffracted and pseudo-physical waves from spatially limited arrays using source–receiver interferometry (SRI)