The 1963 Vajont Landslide: A Numerical Investigation on the Sliding Surface Heterogeneity

The 1963 Vajont landslide is a key case in landslide literature, because it was catastrophic and because a lot of accurate data were collected before and after its occurrence. In this paper, the main focus is on the possible heterogeneity of the sliding surface involved by the landslide motion, which is reflected by a heterogeneous distribution of the dynamic basal friction coefficient μ. Assuming a given zonation of the sliding surface, our strategy was to apply a 2D Lagrangian model to compute the landslide motion and to find the values of μ for each zone, leading to the best agreement between the computed and the observed final deposit. Following some hints from the literature, we have explored heterogeneous configurations composed of up to four different zones, including also the homogeneous case, by means of a 2D numerical model (UBO-BLOCK2) that handles the landslide as a mesh of blocks and runs quickly enough to allow the computation of tens of thousands of simulations in a reasonable computing time. It is found that the four-zone zonation produces the best fit (or the least misfit), which is a strong hint that the gliding surface involved different geotechnical units.