Abstract
The purpose of this presentation is to emphasize the importance of geological understanding in the evaluation of landslides. Only some aspects of this generally very broad topic are discussed, such as the relationship between geomorphology and geology in the evaluation of landslides, the influence of hydrogeological conditions and of soil and rock structure on slope stability.
The geological approach in evaluation of landslides was put into context with respect to the generation and use of engineering models in the sense of IAEG commission 25 recommendations (Parry et al 2014) using the working hypothesis that similar landslides in similar materials are caused by similar processes under similar conditions (Cruden & Lan 2014). Cases where a generally accepted geotechnical (analytical, numerical) model is not consistent with the engineering geological model are discussed.
The examples selected are cases personally investigated by the author and therefore better known to him than examples from literature. Two examples from the presentation are selected to be briefly presented here in this extended abstract.
The example of the Devechi landslide, Azerbaijan shows the mutual relationship of the geology and geomorphology of the slope and the causes of the landslide. On the contrary, the example of the Březno landslide, Czech Republic shows that even in "geotechnically homogeneous" rocks such as Cretaceous mudstones, and within one larger landslide, various types of slope movements interacting mutually in their development may be generated.