Kinematics of a landslide derived from archival photogrammetry and GPS data

The evolution of the Patigno landslide, a deep-seated gravitational slope deformation in the Northern Apennine range (Italy), was investigated using archival photogrammetry, and GPS observations from a permanent station located inside the landslide. Historical aerial photographs of the area taken in 1975 (scale 1:13,000), 1987 (1:13,000) and 2004 (1:30,000) were co-registered into the same reference frame using an unconventional method based on the detection of homologous points in multi-temporal models. Three DTMs were produced using a Digital Photogrammetric Workstation and compared. The displacement vectors of 293 points in the landslide were determined. The average movement velocity of the GPS station since 2004 (about 3.5 cm yr−1) agrees with the mean displacement rate obtained from photogrammetry. Furthermore, the estimated velocity varies seasonally between 3 and 6 cm yr−1. This variability correlated with rainfall suggests that the creep of the landslide is influenced by hydrological factors.