Michel J. Van Camp, Observatoire Royal de Belgique, Brussel, Belgium, Alain Dassargues, University of Liège, Liège, Belgium, Damien Delforge, Université Catholique de Louvain, Louvain-La-Neuve, Belgium, Laurent Delobbe, Royal Meteorological Institute, Brussel, Belgium, Olivier de Viron, U. La Rochelle, LIENSs, La Rochelle, France, Olivier Francis, University of Luxembourg, Luxembourg, Luxembourg, Olivier Kaufmann, University of Mons, Geology and Applied Geology Unit, Mons, Belgium, Thomas Lecocq, Royal Observatory of Belgium, Brussels, Belgium, Marnik Vanclooster, UCLouvain / Earth & Life Inst., Louvain-La-Neuve, Belgium and Arnaud Watlet, British Geological Survey Keyworth, Nottinghamshire, United Kingdom