Assessing the Contribution of ERT Monitoring in Karstic Risks Management by Numerical Simulations and Lab Experiments

Accurate methodologies are required to manage risks linked to land-use planning in covered kart terrains, especially in densely urbanized areas. The main risk lies in the occurrence of a collapse at the base of buildings or infrastructures. These sinkholes often occur suddenly with no warning. The induced damages range from temporary loss of serviceability during repair works to complete destruction and loss of human lives. ERT (electrical resistivity tomography) used in time-lapse mode has shown great promise in monitoring rapid dynamic subsurface processes as the electrical conductivity of rocks and soils depends on their water content, ionic concentrations and clay content. The efficiency of ERT monitoring in detecting cavities rising to the surface is assessed through numerical simulations and laboratory experiments. The aim of the study is to propose an automated detection strategy to manage these risks based on the comparison of the inverted resistivity of each model block to the range of resistivities expected when nothing is changing of every model blocks. These resistivity ranges will be computed from Monte-Carlo simulations to take into account measurement and inversion errors.