Microgravimetry to search for cavities – Construction of the archive building, Marseilles, France

The Provence-Alpes-Côte-D’azur region entrusted Innogeo with a microgravimetry campaign to search for underground cavities before the construction of the regional archives building in Marseilles. Indeed, the possibility of the existence of cavities was
mentioned in the plans for the prevention of natural risks (Plan de Prévention des Risques Naturels – PPRn). Measures, taken during the summer, allowed us to characterise density variations in the underground and define a survey campaign of geological control by mechanical drillings.