PhD in geosciences (M/F) – Characterization of the stress in the seismogenic crust in metropolitan France using a novel technique of azimuthal seismic anisotropy analysis

The objective of this project is to characterize the stress state in the seismogenic crust (between 0 and 20 km depth) in metropolitan France using seismological methods. In particular, the aim is to test and implement a new method based on azimuthal analysis of the temporal variation of surface wave propagation velocities obtained by seismic noise correlation between stations, thus making it possible to determine the orientation of the maximum horizontal stress.

The stress state in the upper crust is one of the least well-constrained parameters directly related to seismicity, fault activity, and seismic hazard, particularly in a context of low deformation and low seismicity such as metropolitan France. Conventional stress estimation techniques are either extremely expensive and rare (e.g., borehole measurements) or indirect (e.g., focal mechanism inversions). This project will test and implement a new method for estimating the orientation of maximum horizontal stress by coupling seismic noise correlation and crustal deformation induced by solid Earth tides. This new information (stress orientation) will serve as a basis for defining the stress state in the seismogenic crust across the entire metropolitan area, including in regions where conventional stress information is very rare and poorly defined. It is also envisaged that analyzing signals in different frequency ranges could allow for the study of the vertical variability of the state of stress.

The project will be conducted in partnership with EDF Seismology and Seismic Hazard Research Group (TEGG, Aix-en-Provence), as part of the SIGMA3 program (international consortium for research and development in seismic hazard,

The project results will serve as input data for future seismic hazard models for metropolitan France. The project's work will therefore be presented and discussed with the community working on seismic hazards as part of the SIGMA3 program, as well as within the framework of the Transverse Seismicity Action of the Epos-France national research infrastructure.

• Master's degree in Earth Sciences specializing in geophysics.
• Strong skills in seismology would be appreciated.
• Strong skills and a strong interest in programming tools and numerical analyses (e.g., Python).
• Scientific curiosity and a drive to develop new technical methods.