Use of combined monitoring remote sensing techniques for the study of active fractures in a remote area: Case of Cima Del Simano rockslide

The Ticino Canton, located in the Swiss Alps, is characterized by steep valleys with important slope instabilities. It particularly affected by rock avalanches and landslides especially after important precipitations.
One of those is the Cima del Simano gneissic mountain in the Blenio valley. The top, reaching an altitude of 2550m, is strongly weathered and presents one main 500 meters-long open fracture and several smaller fractures. Some preliminary satellite InSAR results highlight downward movements. This instability is worthy to be studied since it represents a risk for the road passing at the bottom or villages implanted on its slopes. 
Nevertheless, this mountain is challenging to study because of (1) its bad accessibility: the top without access roads is covered by snow half of the year and (2) the atmospheric effects: the top is often hidden by clouds.  
For those reasons, the study is carried by combining several remote sensing techniques to acquire a maximal amount of information on the instability movements such as rockfalls, topplings and slow deep-seated landslides. Those techniques are extensometers, GNSS, Lidar, satellite InSAR, Ground-Based InSAR (GB-InSAR) and drones Structure from Motion (SfM). They are aimed at confirming the failure scenarios, predicted based on field observations and by structural analyses.  
With Lidar and SfM point clouds one is able to detect small blocks in toppling or sliding, which are confirmed by the results of GNSS and GB-InSAR campaigns, as well as zones of accumulations of rock avalanches debris. By means of GB-InSAR and satellite InSAR one can detect more long-term moving areas (few mm/year). We estimate the limits of those instabilities and their corresponding volume with structural analyses of the discontinuities using Coltop3D and by applying the Slope Local Base Level (SLBL) method. 
For the main fracture, we try to delimit the contours of the instability, but such an aperture and hypothetical instability edges are hardly explained by the actual topography. One explanation is that this fracture was inherited from an older important gravitational event, whose involved material collapsed and was washed out since the event occurred.