Large-scale landslides hazard analysis is based, among other methods, on the numerical evaluation of the safety factor using physical and mechanical parameters measured in the field. The safety factor is determined as the ratio between the forces acting in the favor of sliding phenomenon and the resistance of the earthen massive. The main purpose of the paper is to create two bi-dimensional models of landslides hazard assessment based on the estimation of the stability factor, under different degrees of soil saturation and considering different scenarios of seismic acceleration. Slope stability analysis allows the simultaneity of two exceptional loads such as saturation and earthquake. The first model follows the methodology provided by the national law. In this case, the safety factor is determined by applying limit equilibrium methods using specific geotechnical engineering software. The second model aims to create a deterministic model for safety factor assessment implemented in a GIS system. This one is based on the infinite slope model. The secondary objectives of the paper are: providing theoretical principles, attaining the comparative analysis between the methodologies mentioned above, identifying the critical points of the created models and the reciprocal validation of the results. The study area is a hilly area located in the NorthWestern part of the Iasi City, Romania. The geotechnical parameters were obtained from the laboratory tests carried out on samples taken from 22 boreholes. The geomorphological parameters resulted from the high quality digital elevation model with 1m resolution. The final maps representing the spatial distribution of the safety factor values are reclassified using a common scale. Similarity analysis of the results indicates a good mutual validation.

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The paper presents different methodologies for elaboration of landslide hazard maps at different levels with respect to map scale and elaboration methodologies in Romania: level 1 – national, level 2 – regional, level 3 ‐ detailed. A case study for the city of Iasi (North‐Eastern part or Romania) of detailed landslide hazard and physical risk maps is presented.

Moisture-sensitive or collapsible soils are materials with high porosity that under the loads transmitted by the superstructure or even under its own weight present additional settlements once the soil is saturated. This category includes loess deposits and other high silt content soils with uneven porosity. A method often used for foundation on these soils is the realization of local loessoid material compacted columns. This paper presents, on one hand, the experimental laboratory programs aiming to achieve some optimal mixtures of local material (loess) and different other materials (sand, bentonite, cement) in order to improve the values of the mechanical parameters of the soil and so, to limit the settlements. On the other hand, it presents a lot of settlement calculations for different case scenarios.