An integrated system to monitoring landslide surface movements by means of geodetic techniques

In the Emilia-Romagna region (northern Italy) over 32,000 landslides bodies have been identified: 26% of them have been classified as “active” and the others as “dormant”. As for the state, distribution and style of activity, these phenomena should always be considered as ''reactivated landslides''. Many of them are complex landslides including roto-translational and earthflow movements, often involving fissured clay shales and scaly clays referred in the Italian literature to as “lithologically and/or structurally complex rock types”. These types are characterised by “geological” complexity related to lithological and/or structural features, that causes “geotechnical” complexity such as large and unpredictable variations in geotechnical properties. The high number, at regional scale, of large and periodically reactivated landslides depends primarily on geological causes: generally reactivation occurs following periods of intense or prolonged precipitation events ( snowmelt and earthquakes may also be triggering causes). The application of GPS, Digital Photogrammetry and Laser Scanning to landslide represent a powerfool tool for movement monitoring including small deformation preceding the failure phase. These techniques are applied leading to an integrated system to generate DEMs. Models generated at different epochs can be differenced to determine displacements in active parts of the landslide and the real time monitoring can be well suited for integration with an alert system for landslide hazard management