Structural and Dynamic Numerical Models of Rockslides in the Carpathians and the Alps

Abstract

The stability of rock slopes is often guided by the structural geology of the rocks composing the slope. In this work, we analyse the influence of structural characteristics, and of their seismic response, on large and deep-seated rock slope failure development. The study is focused on the Tamins and Fernpass rockslides in the Alps and on the Balta and Eagles Lake rockslides in the southeastern Carpathians. These case studies are compared with catastrophic rock slope failures with ascertained or very likely seismic origin in the Tien Shan Mountains. The main goal is to identify features allowing to identify seismically induced deformation modes based on the source zone rock structures. We will present examples of classical anti-dip slope and along-strike rock structures that hint at a possible/partial seismic origin, but we will also consider a series of mixed structural types, which are more difficult to be interpreted. This morpho-structural study is supported by distinct element numerical modelling results showing that seismic shaking typically induces deeper seated deformation in initially ‘stable’ rock slopes. In addition, for failures partially triggered by dynamic shaking, these studies can help identify the contribution of the seismic factor to slope movements. The identification of the partial seismic origin on the basis of the dynamic response of rock structures can be particularly interesting for case histories in less seismically active mountain regions (in comparison with the Andes, Tien Shan, Pamirs), such as in the Alps and the Carpathian Mountains.