1. Department of Geological Sciences, School of Mining and Metallurgical Engineering, National Technical University of Athens (NTUA), 157 72 Athens, Greece
2. Institute of Astronomy, Astrophyiscs, Space Applications and Remote Sensing, National Observatory of Athens, 152 36 Athens, Greece
3. GIS and Remote Sensing Laboratory, Division of Applied Geology and Geophysics, University of Patras, 265 04 Patra, Greece