Rockfall hazard assessment in a natural and historical site: The case of ancient Kilistra settlement (Konya), Turkey

The ancient Kilistra settlement is a natural, historical and cultural heritage site in Central Anatolia (Turkey), which makes it an attractive destination for tourists. However, the settlement located on a hill with steep hillsides has suffered from rockfall events, causing the destruction of some historical buildings. The rockfall risk in the region continues to create a serious danger today for land users and visitors during uncontrolled tourist visits. This paper offers an assessment of rockfall hazard for the ancient Kilistra settlement based on experimental investigation and numerical analyses. For the study, comprehensive field studies were carried out, including the identification of slope profiles, scanline surveys on discontinuities and stability analysis of the slopes. The location and size of the fallen, detached and hanging blocks were also identified. Geomechanical properties of the geological units were determined, and also the rockfall risk rating method was applied for the evaluation of the rockfall hazard risk. Runout distance, bounce height, kinetic energy as well as the velocity of the detached and hanging blocks were determined by using two-dimensional rockfall analyses. Based on the results from the rockfall analyses, possible rockfall-based danger zones have been defined for the ancient Kilistra settlement and its close vicinity. The results of this study point at an immediate necessity for the installation of support systems. Findings of the study also offer preliminary data for the description of risk administration strategies and also provide scientific contribution to the study of the hazard and risk resulting from rockfall phenomena.