Natural Hazards and Earth System Science www.nat-hazards-earth-syst-sci.net 1561-8633 1684-9981 5 2 2005 10.5194/nhess-5-285-2005 http://www.nat-hazards-earth-syst-sci.net/5/285/2005/ http://www.nat-hazards-earth-syst-sci.net/5/285/2005/nhess-5-285-2005.html http://www.nat-hazards-earth-syst-sci.net/5/285/2005/nhess-5-285-2005.pdf 285 292 2005-03-18 Preliminary assessment of rockslide and rockfall hazards using a DEM (Oppstadhornet, Norway) M.-H. Derron M. Jaboyedoff L. H. Blikra International Center for Geohazards, Geological Survey of Norway, Leiv Eirikssons vei 39, 7491 Trondheim, Norway Quanterra, Tour-Grise 28, 1007 Lausanne, and Institut de Géomatique et d’Analyse des Risques, University of Lausanne, Switzerland The increasing availability and precision of digital elevation model (DEM) helps in the assessment of landslide prone areas where only few data are available. This approach is performed in 6 main steps which include: DEM creation; identification of geomorphologic features; determination of the main sets of discontinuities; mapping of the most likely dangerous structures; preliminary rock-fall assessment; estimation of the large instabilities volumes. <P style="line-height: 20px;"> The method is applied to two the cases studies in the Oppstadhornet mountain (730m alt): (1) a 10 millions m³ slow-moving rockslide and (2) a potential high-energy rock falling prone area. The orientations of the foliation and of the major discontinuities have been determined directly from the DEM. These results are in very good agreement with field measurements. Spatial arrangements of discontinuities and foliation with the topography revealed hazardous structures. Maps of potential occurrence of these hazardous structures show highly probable sliding areas at the foot of the main landslide and potential rock falls in the eastern part of the mountain.