Seismic imaging works on the same principles as medical imaging: it is a non invasive method to study opaque objects from observations of waves travelling through them. Seismic waves emanating from large earthquakes travel through the earth's mantle and core, interacting with the structures they encounter, and leading to the development of seismic imagery methodologies at the local, regional and global scale.
Recent developments in seismic imagery benefit from the combination of access to data from high quality seismic networks as well as new high resolution imaging tools which are bringing into focus fine scale structure of subduction zones, previously poorly constrained regions of mantle upwelling, as well as details of structure at the core-mantle and inner-core boundaries.
Seismic imagery at IPGP includes the development of methods for imagery of anisotropic structure, providing constraints on past and present flow, the implementation of multi-scale waveform inversion techniques based on accurate numerical methods for wavefield computation, the use of high frequency converted phases to map discontinuities of structure, as well as the development of methods based on information contained in background seismic noise (Ambient noise tomography).
Seismic tomography only provides an instantaneous image of the Earth and it is necessary to complement it with constraints from other fields of Geosciences (e.g. geodynamics, mineral physics..) to obtain a complete understanding of geodynamic processes at play within the Earth.