Natural Hazards and Earth System Science www.nat-hazards-earth-syst-sci.net 1561-8633 1684-9981 6 1 2006 10.5194/nhess-6-33-2006 http://www.nat-hazards-earth-syst-sci.net/6/33/2006/ http://www.nat-hazards-earth-syst-sci.net/6/33/2006/nhess-6-33-2006.html http://www.nat-hazards-earth-syst-sci.net/6/33/2006/nhess-6-33-2006.pdf 33 39 2006-01-02 Site investigation and modelling at "La Maina" landslide (Carnian Alps, Italy) G. Marcato M. Mantovani A. Pasuto S. Silvano F. Tagliavini L. Zabuski A. Zannoni CNR-IRPI – National Research Council of Italy, Research Institute for Hydrological and Geological Hazard Prevention, C.so Stati Uniti 4, 35127 Padova, Italy GRJL – Geo Risk Joint Lab, Palazzo delle Fiere, 32013 Longarone (BL), Italy IHEPAS – Institute of Hydro Engineering of the Polish Academy of Science,7, Koscierska Str., 80-953 Gdansk, Poland The Sauris reservoir is a hydroelectric basin closed downstream by a 136 m high, double arc concrete dam. The dam is firmly anchored to a consistent rock (Dolomia dello Schlern), but the Lower Triassic clayey formations, cropping out especially in the lower part of the slopes, have made the whole catchment basin increasingly prone to landslides. In recent years, the "La Maina landslide" has opened up several joints over a surface of about 100 000 m², displacing about 1 500 000 m³ of material. Particular attention is now being given to the evolution of the instability area, as the reservoir is located at the foot of the landslide. Under the commission of the Regional Authority for Civil Protection a numerical modelling simulation in a pseudo-time condition of the slope was developed, in order to understand the risk for transport infrastructures, for some houses and for the reservoir and to take urgent mesaures to stabilize the slope. A monitoring system consisting of four inclinometers, three wire extensometers and ten GPS bench-mark pillars was immediately set up to check on surface and deep displacements. The data collected and the geological and geomorphological evidences was used to carry out a numerical simulation. The reliability of the results was checked by comparing the model with the morphological evidence of the movement. The mitigation measures were designed and realised following the indications provided by the model.