The Cinque Torri group (Cortina d'Ampezzo, Italy) is an articulated
system of unstable carbonatic rock monoliths located in a very important
tourism area and therefore characterized by a significant risk. The
instability phenomena involved represent an example of lateral spreading
developed over a larger deep seated gravitational slope deformation
(DSGSD) area. After the recent fall of a monolith of more than 10
000 m3, a scientific study was initiated to monitor the more unstable
sectors and to characterize the past movements as a fundamental tool
for predicting future movements and hazard assessment. To achieve
greater insight on the ongoing lateral spreading process, a method
for a quantitative analysis of rotational movements associated with
the lateral spreading has been developed, applied and validated.
The method is based on: i) detailed geometrical characterization
of the area by means of laser scanner techniques; ii) recognition
of the discontinuity sets and definition of a reference frame for
each set, iii) correlation between the obtained reference frames
related to a specific sector and a stable external reference frame,
and iv) determination of the 3D rotations in terms of Euler angles
to describe the present settlement of the Cinque Torri system with
respect to the surrounding stable areas. In this way, significant
information on the processes involved in the fragmentation and spreading
of a former dolomitic plateau into different rock cliffs has been
gained. The method is suitable to be applied to similar case studies.