Integration of laser scanning and thermal imaging in monitoring optimization and assessment of rockfall hazard: a case history in the Carnic Alps (Northeastern Italy)

Rock cliff monitoring to evaluate related rockfall hazard requires a deep knowledge of the geometry and kinematics of the rock mass and a real-time survey of some key features. If a sedimentary rock system has sloping discontinuity planes, an open joint could become a potential sliding surface and its conditions must be monitored. It is the case of the Passo della Morte landslide (Carnic Alps, Northeastern Italy), where sub-vertical joints exist. Remote sensing techniques such as terrestrial laser scanning (TLS) and infrared thermography (IRT) allow a fast and efficient contactless geometrical and geomechanical examination of a rock mass. Therefore, they can be used to recognize those joints that require monitoring with on-site instrumentation such as extensometers and/or inclinometers, or also acoustic emission sensors, aiding the arrangement of monitoring systems which are generally quite expensive to install. Repeated IRT surveys would provide useful information about the evolution of unstable slopes, thus suggesting how the on-site monitoring system could be improved. Moreover, data gathered by TLS and IRT can be directly used in landslide hazard assessment. In the test site, an open joint was recognized together with a fair joint that could change in the next future. The results were validated by means of extensometer data.