Topographic migration of GPR data: Examples from Chad and Mongolia

International audienceMost Ground Penetrating Radar (GPR) measurements are performed on nearly flat areas. If strongly dipping reflections and/or diffractions are present in the GPR data, a classical migration processing step is needed in order to determine the geometries of shallow structures. Nevertheless, a standard migration routine is not suitable for GPR data collected on areas showing a variable and large topographic relief. To account for the topographic variations, the GPR data are, in general, corrected by applying static shifts instead of using an appropriate topographic migration which would place the reflectors at their correct locations with the right dip angle. In this article we present an overview of Kirchhoff's migration and show the importance of topographic migration in the case where the depth of the target structures is of the same order as the relief variations. Examples of synthetic and real GPR data are shown to illustrate the efficiency of the topographic migration