Contribution of geophysical methods to the detection of underground cavities in salt series. Development in different projects in Morocco (roads, rail, etc…)M.K. Tlemçani, L. Ait Brahim, A. El Mahsani and A. LabrihmiMATEC Web Conf., 149 (2018) 02083DOI: https://doi.org/10.1051/matecconf/201814902083