Distribution of landslide volume in tectonically-controlled mountain landscapes

Despite faults are known to influence rock slope stability, the interactions between fault zones and slope deformations are poorly documented in regional scale studies, and their relationships remain poorly understood. In this work, we define the possible role of Quaternary faults in favouring slope instability in a tectonically-controlled landscape. We analyse the distribution of landslides in the Peloritani Mountains, NE Sicily, Southern Italy, a tectonically active region where landslides are abundant. For the purpose, we analyse a set of thematic layers, including (i) a detailed landslide inventory map prepared through the visual inspection of aerial photographs of different vintages, (ii) a map of recent faults and associated triangular facets, also identified through the visual interpretation of aerial photographs, (iii) geological and geomorphological data, and (iv) maps showing morphometric indices obtained from a 2 m × 2 m DEM. Geomorphological and photo-geological mapping revealed a spatial association between the gravitational displacements and the tectonically-controlled landscape modifications conditioned by the presence of faults crossing the mountain slopes. We find that the total landslide volume is dominated by a few large landslides clustered where high local relief and main recent fault segments coexist. Based on our findings, we hypothesize that the distribution of landslide volume is a proxy for the mid- to long-term activity of the faults. Our results highlight the role of the large-scale slope failures on the geomorphological evolution of a tectonically active area, and suggest a positive feedback between tectonic and gravitational deformations in active mountain belts.