This paper reports the results of a geotechnical investigation on a huge landslide which develops in a tectonized, fissured and heterogeneous clay and clay shales formation of the Southern Apennines, Italy. Inclinometer profiles, GPS and topographic displacement measurements were used to reconstruct the 3D geometry of part of the slip surfaces and the displacement fields, both superficial and deep. Displacement rate differences from site to site, due to several causes, were analyzed with reference to their effects on an overpass of the highway – which was consequently removed – and on the earth thrust on the railway tunnel crossing the landslide foot.