In-situ geophysical characterizations of earthquake recording stations are essential toward the effective use of ground motion records by the earthquake engineering community to mitigate seismic hazards. The current methods used for seismic site characterization rely on array-based recordings of surface-waves. These methods determine the site dispersion curves from surface-wave phase velocity versus frequency (or wavelength) relations before inverting the curves to model the site shear wave velocity (VS) versus depth profiles. VS profiles are then used to calculate the site’s time-averaged VS of the upper 30 m (VS30) for use by engineers in developing ergodic GM regression models, and/or in combination with the site GM recordings, to directly estimate the site-specific seismic response. In recent years, an important effort was initiated by several countries to improve the state-of-knowledge about geophysical site characterization methods with the aim toward robust and consistent characterizations (VS, VS30, etc.). Much work still remains to be done with respect to the characterization of site conditions at network stations and the improvement of the methods selected and their implementation. The proposed post-doc position will consist of participation in the current effort of seismic station characterization, as well as the optimization of their implementation: 1/ The post-doctoral candidate is expected to participate in geophysical surveys of seismic stations located in European, 2/ The candidate is expected to improve acquisition parameters in order to optimized subsequent surveys 3/ Finally, the candidate is expected to be involved within the COSMOS guidelines project and assist organizers within the project advancement and guidelines writing coordination.