Active Landslide in Ticino

Forensic investigation of an active landslide in Ticino, Switzerland: Creating a geological and chronological model for the Cerentino landslide

Student: Kevin Schöngrundner

Supervisors: Dr. Andrea Wolter, Prof. Simon Löw

In mountain ranges such as the Alps, deep-seated gravitational slope deformations (DSGSDs) are common phenomena (Crosta et al., 2013). Cerentino is a village of 61 inhabitants, located in the Rovana valley in the southern part of Switzerland (Canton Ticino). Various measurements taken over the last 30-40 years and multiple events indicate that the slope on which Cerentino is situated is actively deforming. In this Bachelor thesis, several aspects of the landslide are studied in more detail. The assumed sliding surface scar of the Cerentino landslide is obvious on a hillshade and in the field. The main aim of this Bachelor thesis is to characterize this scar and to understand (1) how the failure initiated and evolved and (2) when the sliding body moved. This thesis is part of a larger research project commissioned by the Canton Ticino to ETH Zürich, to better understand the active landslide of Cerentino and to evaluate possible measures to decrease the present creeping rates (Löw and Wolter, 2015). The work includes the production of a conceptual model, which explains how the creeping mass moved in the past. Several methods were used: during a first phase, a study of remote sensing imagery was performed, while the second phase consisted of fieldwork. The remote sensing study produced a morphological map, while during the fieldwork discontinuities and the foliation on the sliding scar were measured and analyzed in order to perform a rock mass characterization. During fieldwork vegetation dimensions (lichens and conifers) were also measured in order to get more information about the age of the landslide. The main results of this Bachelor thesis suggest that the Cerentino sliding body moved catastrophically along the basal sliding surface in the past. This catastrophic movement happened a long time ago, but no longer than 20’000 years ago (Last Glacial Maximum), as no glacial marks can be observed on the sliding surface scar.