The morphodynamic evolution of the Costa Gaveta slope and landslides is strongly influenced by systems of structural faults. Long term monitoring of deep and superficial displacements allows the description of the displacement field of an eartflow in clay shales and of the smaller earth-debris flow occurring in its main scarp along a fault line. The inclinometer data show the current independence of movements of the two phenomena. The mechanism of movements of the main earthflow in the channel consists in sliding on a thin shear zone, with an average annual displacement rate, constant in the monitoring period, with seasonal variations in the same order of magnitude of the average annual rate. Displacements are strongly correlated to rain with a threshold above which water runs off. Pore pressures response to rain is characterized by a noticeable delay and their variations on the shallowest areas of the slip surface have the greatest influence on the landslide movements.