Rockfall Risk Management System Based on Multi Parameter Rating System for Humans in Inaccessible and Isolated Settings of Cultural Heritage: Application on Nisyros Island, Greece

Cultural heritage is expressed through monuments and temples that are sometimes isolated and constructed on steep rocky slopes, with limited access to visitors. Frequently, the adjacent environment suffers from geological changes and presents instability phenomena of the rocky slopes, mainly rockfalls or rockslides. It is well known that rockfalls are related to substantial incidents of fatalities, independently of their volume especially in areas characterized as "areas with highly touristic concentration". In this study, a rockfall risk rating system for rock slopes which are adjacent to monuments is proposed, as part of rockfall risk management system, which is based on geological, geomorphological criteria and human behavior under dangerous situations (i.e., rockfalls). This rating system was applied to distinct sections along a pedestrian road at the base of a slope at Nisyros Island, Greece demonstrating the variability of rockfall risk for tourists and pedestrians. This study has considered, for the formulation of the rockfall risk management system more detailed governing parameters such as interference with vehicles, visibility of the entire slope, existence of forest, structural and discontinuities index, pedestrian or tourist concentration and behavior etc. Moreover, in quantitative point of view, the application of the aforementioned system indicates that the probability of injury to pedestrians in summertime is considerable, thus protection measures should be applied, in order to reduce the pedestrians' risk. In addition, the velocity of the rocks when a rockfall occurs estimated to be in the order of magnitude of 0.6 ms-1, which is capable of causing serious injuries.