Detection of subsurface cavities in the structurally bounded Labe prefecture area, Republic of Guinea using two-dimensional electrical resistivity tomography (ERT)

Résumé fourni par la source

This study is conducted within the Gambia River Basin Development Organization Energy Project (OMVG) framework. The construction of a high voltage interconnection network fed by a hydropower station to supply electricity to OMVG Member States was done on stable ground. During the installation pits for the pylons in Labé Prefecture, Republic of Guinea, cavities were discovered in the geological formations during the initial planned route. Structurally, the study area is bounded by two major faults to the east and west of northeast direction. The geomorphology is made up of a central plateau, intermountain depressions, piedmont plains, talwegs, and glacis. Geological investigations were obtained by a geophysical Two-dimensional Electrical Resistivity Tomography (ERT) method. The results show that the synthetic lithological profile from top to base was sandy-clayey soil, hard cuirass, and a layer of gravel followed by a mottled zone comprising an indurated part and an imbibed part just before the source rock. The cavities were observed probably because of the dissolution of certain minerals constituting the weathering crust due to the infiltration, underground waters, and the seasonal variation in the level of the surface watercourses. Geophysical results showed a very good agreement with the visual observations.

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.