We present field evidence and a kinematic study of a rock block mobilized in the Ponti area by a M _w = 6.5 earthquake near the island of Lefkada on 17 November 2015. A detailed survey was conducted using an unmanned aerial vehicle (UAV) with an ultrahigh definition (UHD) camera, which produced a high-resolution orthophoto and a digital terrain model (DTM). The sequence of impact marks from the rock trajectory on the ground surface was identified from the orthophoto and field verified. Earthquake characteristics were used to estimate the acceleration of the rock slope and the initial condition of the detached block. Using the impact points from the measured rockfall trajectory, an analytical reconstruction of the trajectory was undertaken, which led to insights on the coefficients of restitution (CORs). The measured trajectory was compared with modeled rockfall trajectories using recommended parameters. However, the actual trajectory could not be accurately predicted, revealing limitations of existing rockfall analysis software used in engineering practice.

Rockfalls pose significant hazard on human activities and infrastructure. The assessment of rockfall risk along roads and on other human activities is of great importance. Geological assessment can predict the outbreak of such events; explain the mechanism of occurrence and assist in the effective design of protection measures. The trajectory of a falling block is significantly affected by its response to the impact with the slope, since block kinematics properties mainly depend on the coefficient of restitution values. In this research a laboratory procedure based on the free fall of small blocks of different rock types and artificial materials was implemented in order to address the effect of their mechanical properties on the coefficient of restitution values. From the evaluation of testing results a correlation between kinematic coefficient of restitution and Schmidt rock hardness is proposed.