Landslide susceptibility analysis in a mountain basin of Argentinean Central Andes (31ºS).

JEANNERET P.; MOREIRAS S.M.

In Bouza, Bilmes Rabassa (Eds): Advances in Geomorphology and Quaternary Studies of Argentina 3.

Springer

Año: 2021;

Landslide susceptibility analyses are performed considering the contributing factors to the instability of the affected slopes. In high mountain areas of the An-des, the steeply-dipping slopes left by past glacier advances are prone to collaps-ing, which makes the study of the existing slope´s present conditions important. In this study, a general tendency was analyzed considering angle, orientation and li-thology of the slopes with special emphasis on the original detachment scars that sourced each event. The use of Digital Elevation Models in a GIS environment have resulted fruitful in the past for this type of analysis in remote, vast areas and were applied in this study to analyze the stated parameters. The latter were con-trasted with the geologic map including Quaternary deposits and the landslide inventory map. Results have shown that Quaternary deposits source the vast majority of the large scale landslide events and its occurrence are linked to the de-stabilization of glacially dumped geoforms. There is no strong correlation between the estimated slope angle prior to the collapses and the detachment scar orientation, which is associated to lithological structures from the Frontal Cordillera of San Juan and the placing of the moraine deposits. The altitude of detachment scars also show remarkable results were almost 70% of the mobilized area is sourced under the 3500 m asl limit. These results differ from regional-scale observations were mostly high altitude, deeply-steeping and highly-fractured rock outcrops are involved in large landslides. When we include Quaternary deposits to the analysis of a smaller area, the results show how prone they are to collapsing once the glaciers retreat.