Deep seated rock slope instabilities, long term real-time monitoring and collapse forecasting

Large deep seated slope deformations in alpine areas are generally characterized by slow to extremely slow present day displacements. Nevertheless, some large rockslides can develop within the deep seated deformation masses. These rockslides can become unstable and can further accelerate up to a collapse phase. We present two case studies from the European Alps for which both in situ and remotely sensed monitoring (GB-InSAR) data are available and which allow some general observations and conclusions to be drawn relatively to the possible collapse. Time series obtained from GB-InSAR provide a large amount of spatially distributed displacement data both in debris covered and rock outcropping areas. Such improved information, validated by ground-based measurements, allow to establish new velocity and displacement thresholds for early warning purposes