Slope instability and sagging reactivation at Maratea (Potenza, Basilicata, Italy)

The present work shows results collected, through a long-term monitoring, on slope movements in the Maratea Valley (Potenza, Italy). The investigated area shows large-scale gravitational phenomena and sagging type morphology that have been well-described in previous works. Electronic Distance Meter (EDM) measurements were first taken in 1983 and from these it would appear that since about 1991 there has been an acceleration in the movement occurring in the upper part of the valley, where sagging is located and which was previously motionless. Seismic and rainfall series for the last 20 years have been examined. The data collected show that this sagging destabilisation could not be related to rainfall and recent seismic activity; the latter reactivating later, in 1998. Global Positioning System (GPS) data on a network including benchmarks located outside of the landslide area, and comparison with EDM data indicate that movement affected the surrounding mountain slopes, widening the valley and destabilising the sagging: thus suggesting a relationship between the sagging and tectonic activity. (C) 2003 Elsevier B.V. All rights reserved.