Rockfalls pose a significant risk to human activities and infrastructure. The assessment of rockfall risk is critical in deligneating zones of higher risk and mitigating effectively the potential impact from such events in inhabited areas. Risk assessment relies heavily on predicting accurately the trajectories of falling rocks, considering various factors such as the rock slope characteristics, the properties of the falliing rocks, the triggering mechanism and other. In the last two decades, risk assessment is performed more frequently using three dimensional rockfall analysis allowing for more robust asssement of risk.
The paper presents an example of a 3D rockfall analysis, which assessed the risk from rockfalls at a cultural heritage site in Central Greece. The site is characterised by an Acropolis situated at the crest of a promontory, which is formed by steep limestone slopes. Following detailed UAV surveying of the study area, engineering geological mapping of rockfall prone areas, discontinuity mapping using different techniques and field measurements to identify the prevailing conditions on the slope, the analyses where performed using Rockyfor3D software in order to calculate the rockfall trajectories under different scenarios.
The 3D analyses results were compared to 2D rockfall analyses, to evaluate the accuracy of the two approaches. It was concluded that the 2D analysis predicted well the rockfall trajectories, in relation to the 3D analyses, but the zoning of high risk zones was only possible when the 3D analyses where utilised. Different scenaria (i.e. earthquake triggered events) were assessed to determine the appropriate mitigation measures and zone areas where no further development should take place.