“…Understanding the origin and evolution of such instabilities implies the continuous monitoring of the various parameters characterizing the deformation process and its environment. Studies of rock slope stability often involve the monitoring of displacements (e.g., Kennedy and Niermeyer, 1970;Bhandari, 1988;Brunner et al, 2000;Mayer et al, 2000;Zvelebil and Moser, 2001) or morphological changes (Mikos et al, 2005;Dewez et al, 2007;Collins and Sitar, 2008) and less frequently the seismic monitoring, which was performed earlier for unstable slopes in open mines (Kennedy and Niermeyer, 1970;Hardy and Kimble, 1991) and more recently for natural slopes or cliffs (Willenberg et al, 2002;Senfaute et al, 2003;Kolesnikov et al, 2003;Eberhardt et al, 2004;Amitrano et al, 2005;Roth et al, 2005;Brückl and Mertl, 2006;Spillmann et al, 2007;Willenberg et al, 2008;Senfaute et al, 2009). Most of these studies were devoted to the monitoring and study of discrete seismic events.…”