Christian Dupuis (a), Florence Quesnel (b,c) & Jean-Marc Baele (a)
(a) Geology and Applied Geology, Faculty of Engineering, University of Mons, 20 Place du Parc, 7000 Mons, Belgium. E-mail: Christian.DUPUIS@umons.ac.be
(b) BRGM (French Geological Survey), DGR/GAT, 1, Av. Cl. Guillemin, BP 36009, 45060 Orléans Cedex 2, France.
(c) UMR 7327 of the CNRS/INSU, Orléans University & BRGM, 1A rue de la Férollerie, 45071 Orléans, France.