Geophysical Survey of the Grand Place in Brussels - An Example of Prospection in an Urban Context

In urban contexts geophysical prospection faces specific difficulties resulting from the limited size of the available areas, the presence of numerous sources of both geophysical and electromagnetic noises, the soil surface material and eventually crowd. At the Grand Place in Brussels GPR and electrostatic (capacitively coupled resistivity) surveys were associated. The low resistivity of the clayed substratum limits GPR to very shallow depths, which is compensated by the use of three different offsets for the electrostatic arrays corresponding to 1, 1.5 and 2 m depth of investigation. The underneath features anterior to the end of the XVII century can thus be evidenced.