Large urban areas are composed of volcanosediments in Northern Hungary. The study area of the Avas Hill being the southern part of the Tardona-hill is located in the city of Miskolc with a maximum height of 211m. Steep slopes (25-65°) of the Avas Hill extending over 0.75 km² are densely built-in with small houses and worship places as well as more than 500 cellars. The less utilized road network, however, is in poor conditions. The extensive network of cellars and the heterogeneity of geological formations increase geological risks and induce landslides and surface instabilities on the steep slopes. In this present study one aspect of a 3-level instability analysis is discussed regarding the geological layers of Avas-North with the damages and the triggering mechanisms.

The stability analysis is based on the engineering geological properties of the site. Initial stages involved fieldwork with in situ testing (rockmass classification, non-destructive strength determination), geological mapping as well as laboratory analysis both non-destructive (unit weight, effective porosity, ultrasound velocity) and destructive tests (UCS, modulus of elasticity, Poisson ratio and Brazil test). The laboratory and field test results were used as input parameters for computer modeling with FEM of slope stability. The models were calculated for undisturbed slope and also for slope with cellars and other cavities as well as concerning the surface load caused by building and other dynamic loads. The results show that the model predicts possible failures on the hill.