Rockfall hazard assessment in a cultural and natural heritage (Ortahisar Castle, Cappadocia, Turkey)

The Cappadocia region is one of the most important tourism centers of Turkey owing to its natural beauty and historical heritage. The natural landscapes predominantly contribute to the tourism capacity of the region. This is controlled directly by the characteristic lithological units and surface processes. However, rockfall events, which are sometimes observed in the region, are typical natural hazards conditioned by discontinuities, steep topography and human activities. The Ortahisar Castle is one of the natural monuments and also one of the historical places of this region. This castle is located on a steep hill formed by jointed ignimbrite and its height and settlement area are approximately 50 m and 500 m, respectively. However, some blocks on the castle have begun to exhibit serious rockfall potential. Rock hewn structures carved by man for various purposes contribute to increase in rockfall hazard. For this reason, the castle was closed to touristic visits. The purpose of this study was to evaluate this hazard potential and perform a series of rockfall analyses and discuss the results. Besides, location and dimension of fallen blocks were determined. At the final stage of the fieldwork, location and size of detached blocks having potential to fall were described. During the analysis stage, runout distance, bounce height, kinetic energy and velocity of the detached blocks were determined by using Rocfall V.4 software. The results obtained from rockfall analyses were used to map the areas under rockfall threat in the close vicinity of the castle and the potential risk was interpreted. © 2008 Springer-Verlag.