The Critical Zone is the thin habitable layer on the surface of our planet Earth. It is a interface compartment where different spheres meet and interact (atmosphere, hydrosphere, lithosphere, and biosphere). It is this reactivity with that allows life to develop “on” Earth, or rather in the Critical Zone. In order to study this Critical Zone and the processes that makes our planet habitable, we are faced with physical limitations: the ground and subsoil are not transparent, and access to them is limited to methods that are generally destructive, such as sampling or drilling.

To overcome these limitations, geophysical methods offer a number of definite advantages. These are non-intrusive methods, often used from the surface (or between boreholes where they exist), which allow imaging the distribution of physical properties or monitoring of processes through repeated measurements.

This issue of Comptes Rendus Géoscience provides an overview of the use of geophysical methods for studying the structures and dynamic processes of the Critical Zone (Figure). Since a previous special issue on “Hydrogeophysics” in 2009 in Comptes Rendus Géoscience, numerous methodological developments and new applications have emerged in the scientific community.