A multidisciplinary investigation of deep-seated landslide reactivation triggered by an extreme rainfall event: a case study of the Monesi di Mendatica landslide,Ligurian Alps

Landslides - In November 2016, an extreme rainfall event affected the Ligurian Alps (NW Italy). Consequently, several landslides and debris flows occurred in the upper Tanarello stream basin. In...     

The use of the automatic inclinometric system for landslide early warning: the case of Cabella Ligure (North-Western Italy)

Following the flood events occurred in the 1993 autumn, a landslide affecting the village of Montaldo di Cosola was reactivated. Montaldo di Cosola is a small village located in North-Western Italy, on the Appennines Mountains. Historical data report of at least another similar episode occurred about one century ago.The landslide takes place over debris deposits, which are about 20–35 m deep, produced by an ancient landslide event. Underneath these debris deposits there is an altered layer of the calcareous-marly substratum of the Antola formation. The landslide, almost certainly triggered by the incision of the torrent Rio Montaldo, has a probable rotational geometry and takes place through slow and progressive continuous movements. The landslide typology impedes a precise dimensional definition. Only the order of magnitude of the main scarp width, which is of hundreds of meters, and the order of magnitude of the landslide volume, which is of some hundreds of thousands of cubic meters, can be indicated.A complex monitoring network has been installed in the area. This network includes an automatic inclinometric system (AIS) that automatically performs measurements, twice a day, along the entire length of a pipe that is 45 m deep. Measurements are taken every 50 cm and are then broadcasted to a remote station located in Torino.After the exceptional meteorological events occurred in October 2000, the AIS measured significant movements that have not yet stopped. On the basis of these available data it has been possible to locate the sliding surface at a depth of about 13 m at the level of a sandy–silty layer with some clay lenses inside. The movements measurements performed so far reveal a good correlation with the rainfalls. In particular it has been possible to identify a time lag of about 8–9 days between the occurrence of a rainfall peak and the corresponding peak in the recorded movements that were produced by these rainfalls.     

UNESCO World Heritage sites in Italy affected by geological problems, specifically landslide and flood hazard

A National Research Council, Research Institute for Hydrogeological Protection (IRPI) study on Italian monuments included in the UNESCO World Heritage List has revealed that many are affected by geological, geomorphological, and engineering geological problems. These monuments are static entities set in an environment that often manifests highly dynamic processes. As part of the efforts to protect sites of cultural and natural heritage, this study has applied a preliminary and empirical Geographical Information System-based method developed to characterize the environmental hazards at the sites where the monuments are located. Because the study of hydrogeological degradation falls within the province of IRPI, this hazard zoning focuses on river and mountain slope dynamics specifically concerning landslides and floods.     

LIDAR monitoring of mass wasting processes: The Radicofani landslide, Province of Siena, Central Italy

The Radicofani Basin, stretching about 30 km NW–SE, is an intra-Central Apennine basin connected to Pliocene–Pleistocene extensional tectonics. It consists of an Early to Middle Pliocene succession including essentially shelf pelites. In the Radicofani area, province of Siena (Tuscany region), morphodynamic processes are very frequent with widespread badlands and rapidly evolving mudflows. In order to evaluate the general instability of the Radicofani area, geological and geomorphological surveys were carried out. The 1954, 1990 and 2003 aerial surveys allowed a comparison of the changes in the various morphological aspects of the study area, which suggested an increase in slope instability with time. A new complex translational landslide evolving into mudflows, activated during the winter of 2003, was monitored using an experimental system based on terrestrial LIDAR (Light Detection and Ranging) and GPS (Global Positioning System) technologies. This system allowed the monitoring of the morphologic and volumetric evolution of the landslide. A comparison of the monitoring data of October 2004, June 2005, May 2006 and May 2007 points out that the evolution is characterised by the sliding of displaced materials. A volume of about 1300 m³ of materials was removed during the period 2004–2005, 300 m³ for 2005–2006, and 400 m³ for 2006–2007. The greater initial mass movement probably reflects a greater static imbalance during the early period of landslide movement and increased rainfall. Therefore, the proposed monitoring system methodology allows the numerical evaluation of the landslide morphological evolution and to validate the landslide evolution model based on geological and geomorphological field surveys.