Geophysical detection and structural characterization of discontinuities in rock slopes

The stability of a potentially unstable rock mass strongly depends on the discontinuity pattern and the face topography. Basic geological analysis could provide useful structural information but suffers from the lack of information on discontinuities at depth. Of major importance is the persistence of discontinuities inside the mass. Several geophysical methods (seismic, electric and electromagnetic) are available to address this problem, differing in sensitivity, resolution and depth penetration. The purpose of the chapter is to present the common structural and geophysical methods for characterizing the rock mass. Section 2 is dedicated to a review of the main geophysical parameters and the properties of the main geophysical methods, as well as their possibilities and limitations for discontinuity detection and characterization. In section 3, applications of the aforementioned methods are shown for three limestone cliff sites located around Grenoble (French Alps), exhibiting different geometrical and geotechnical features