Multi-temporal morphological analysis coupled to seismic survey of a mass movement from southern Italy: a combined tool to unravel the history of complex slow-moving landslides

Impressive and large-scale slow-moving landslides with a long-term evolutionary history of activity and dormancy are a common landform in the southern Apennines mountain belt. The spatial and temporal evolution of a multi-stage complex landslide located in a catchment of the frontal sector of the southern Apennine chain was reconstructed by multitemporal geomorphological analysis, near-surface seismic survey, and DEM comparison. The Tolve landslide shows a multi-decadal evolution characterized by intermittent periods of activity and dormancy. Geomorphological evidences suggest that the initial failure of the large-scale landslide has a multi-millennial age and can be related to a roto-translational movement that evolved in an earthflow. Recent evolution is associated with a major reactivation event in the middle and lower sectors of the larger complex landslide, which probably is related to a heavy rainfall event occurred in January 1972. Recent evolution is mainly associated with minor movements in the source area, toe advancements, and widespread shallow landslides along the flank of the earthflow. Our results demonstrate the need to integrate traditional geomorphological analysis with multi-source data to reconstruct the evolution of slow-moving landslides and to identify their main predisposing and triggering factors.