GNGTS 2021 - Atti del 39° Convegno Nazionale

GNGTS 2021 S essione 2.1 156 Back-analysing slope movements involves determining the shear strength of the soil mass, given the conditions that existed at the time of failure, such as the pore-water pressure distribu- tion, the characteristics of the seismic load, and the geometry and slip of the sliding surface. The latter could be unknown in the case of non-catastrophic slope movement involving blind surfa- ces, as in this case study. To estimate the required parameters, we followed these steps: 1. Estimation of the geometry and slip distribution of the potential sliding surface by analyti- cal inversion of the observed InSAR displacement, assuming a planar source embedded in an elastic medium; 2. Assessment of the critical soil strength parameters by performing a pseudostatic limit equilibrium analysis of the slope, considering the slip of the sliding surface, the seismic input and the critical acceleration ( a c ) of the slope; 3. Validation of the computed strength parameters by comparison with those provided by laboratory and in situ surveys. Fig. 1 - (a) Sketch of the Etna volcano area. The coloured pattern identifies wrapped ground displacements from the Sentinel-1 descending interferogram (22/12/2018 – 28/12/2018), and highlights the deformations caused by the Mt Etna volcanic inflation, the December 26 M w 4.9 earthquake along the Fiandaca Fault, and the mass movement to the west of Paternò village. (b) LoS displacement pattern along the ascending (left) and descending (right) orbits given by the processing of the S-1 data in the time interval of December 22 – 28, 2018.