Alessandro, De Pedrini and Christian, Ambrosi and Maurizio, Pozzoni (2023) Monitoring and evolutionary analysis of the Cadegliano Viconago landslide between Switzerland and Italy. In: Swiss Geoscience Meeting 2023, 17-18 November 2023, SUPSI DACD.
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Abstract
The landslide of Cadegliano Viconago in the province of Varese (IT) has been for over twenty years a danger to the population and infrastructures located along the course of the Tresa river, at the border between Italy and Switzerland. The landslide leads to the accumulation of debris which has caused flows in several events on the provincial road passing at the foot of the landslide. The slope even shows traces of deep damage which manifests with the exposure of scarps and traction fractures, with even centimeter displacements during the most intense rainfall events. A catastrophic collapse would lead to the partial or total interruption of the road system, a barrage of the Tresa river with the possible formation of a basin and the destruction of a well field for drinking water use in Switzerland. Even though in recent years of monitoring it was observed a trend towards smaller displacements, intense and prolonged rains could drastically influence the dynamic behavior of the landslide and cause a catastrophic failure. For this reason, thanks to the financing of an Interreg project with the involvement of the Interregional Agency for the Po River and the Canton Ticino Land Department, two DMS (Differential Monitoring of Stability) columns were installed in March 2021 to investigate the landslide activity and to define alert thresholds. DMS multiparameter columns provide continuous data with detailed displacement, accelerometric, and piezometric measurements. The deep monitoring data joined by geodetic measurements since 2006, provide information on the landslide’s dynamics. The monitoring, the cores from the drilling, and the in-situ surveys provide a basis to set a numerical stability model to understand the slope kinematics and the response to the water table changes. Although the first years of monitoring with the DMS columns were devoid of intense and prolonged rains, the rainfall/displacement relation is appreciable analyzing the most intense rain events recorded in autumn 2002 and 2014. In that period, the humidity status identified by the Standard Precipitation Index (SPI) showed a very high value and coincided with the opening or extension of tensile fracture. Regarding the volume affected by the disruption, our analysis suggests a slip surface at a depth of about thirty meters which can plausibly lead to the detachment of a volume mass ranging from 70’000 to over 2’000’000 m3. The numerical stability model was followed by expansion models of the unstable mass which produced scenarios with possible consequences also in Swiss territory.
| Item Type: | Article in conference proceedings or Presentation at a conference (Speech) |
|---|---|
| Subjects: | Physical sciences > Geology Physical sciences > Geology > Earth science Physical sciences > Geology > Geohazards |
| Department/unit: | Dipartimento ambiente costruzioni e design > Istituto scienze della Terra |
| Depositing User: | Alessandro De Pedrini |
| Date Deposited: | 06 Dec 2023 11:25 |
| Last Modified: | 06 Dec 2023 11:41 |
| URI: | http://repository.supsi.ch/id/eprint/14755 |
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