Development of methods for imaging the complete waveform and/or observable extracts from recorded signals

Seismic imaging is at the heart of many of the team’s projects, with applications at various scales from the laboratory to the global Earth, including the near surface, crustal structures such as oil reservoirs or volcanoes, lithospheric structures and even the upper mantle.

Listening can be active (shooting), passive (earthquakes) or without sources (ambient noise) : the team is involved in these three types of listening with reciprocal interactions.

The near surface is also probed by electromagnetic waves, especially on unstable structures or glaciers.

We are developing new methods to reconstruct the heterogeneity of subsoil physical parameters (wave velocities, density, attenuation, anisotropic parameters, porosity, fluid saturation, conductivity and
electrical permittivity,...) by adjusting the observed data to quantities
corresponding modelled in complex 2D and 3D environments.

These models require significant IT resources for data storage, simulations and computing resources (access to CIMENT resources in Grenoble and to national supercomputer resources (IDRIS, CINES and CCRT). It is necessary to support their use with the appropriate human skills.

The non-linear optimization problem is at the heart of complete waveform inversion and ambient noise correlation tomography, requiring expertise in applied mathematics.

The study of other geophysical investigation methods (gravimetry, electromagnetic diffusion, etc.) is in full development within the team.

The couplings between these different investigation methods make it possible to better constrain the reconstruction of the environment. In particular, the coupling between electrical and electromagnetic waves is an active, difficult but promising area of research.

Our projects are funded by the ANR, a research and development consortium supported by about ten oil groups (SEISCOPE). Our collaborations
international academic level are numerous on these subjects.

Figure : Seismic and acoustic imaging at all scales.