Aptitude of different geophysical methods for the permeability and stability analysis of a gypsum substratum

A big landfill implantation above a sub stratum formed by a sequence of shales and gypsum over massive karstified gypsum beds, raises that potential damages in the bottom of the dumping area may occur. This damage could be related with quickly karstic structure development. Different geophysical methods aptitude (electromagnetics, GPR, gravimetry and refraction seismic) have been analysed to detect and define karstic structures, as weIl as to establish compositional variation in depth (15 m). Obtained results suggest that the combined application of these geophysical methods over a massive gypsum substratum may detect and define karstic structures in depth, the lithology composition, grade of permeability, and the subsurface structure. Special attention may be highlighted on the correlation between electrical resistivity in two depth levels (7.5 and 15m) obtained from the electromagnetic data, and the compositional variation in depth (shale / gypsum content). Geophysical data interpretation has been underwritten by a later drilling campaign that verified the obtained results.