Preliminary remarks on monitoring, geomorphological evolution and slope stability of Inca citadel of Machu Picchu (C101-1)

The geology of Machu Picchu area is characterized by granitoid bodies that had been emplaced in the axial zones of the main rift system. Deformation of the granite, caused by cooling and tectonic phases, originated 4 main joint sets, regularly spaced (few decimeters to meters). Several slope instability phenomena have been identified and classified according to mechanism, material involved and state of activity. They are mainly related to rock falls, debris flows, rock slides and debris slides. Origin of phenomena is kinematically controlled by the structural setting and relationship with slope face (rock falls, rock slide and debris slides); the accumulated materials are the source for debris flows. Geomorphological evidences of deeper deformations are currently under investigation. A low environmental impact monitoring system has been established on the area with the purpose to minimize equipments usage and, in the mean time, to collect reliable data on surface deformations. The monitoring network is based on a GPS, multitemporal laser scanner survey, Ground based Radar interferometry (GB-SAR) and Satellite Interferometric Synthetic Aperture Radar (InSAR). The preliminary results are partially confirming the field evidences of slope deformation but, in the mean time, they require a longer period of observations since the sliding processes are relatively slow.