Identification of Rock Fall Prone Areas on the Steep Slopes Above the Town of Omiš, Croatia

Abstract

The aim of this paper was identification of rock fall prone areas above the historical town of Omis, located at the Adriatic coast in Croatia. Unstable areas were identified by kinematic analysis performed based on relative orientations of discontinuities and slope face. Input data was extracted from the surface model created from the high-resolution point cloud. The town of Omis is threatened by rock falls, because of its specific location just at the toe of Mt. Omiska Dinara. Rock fall risk is even higher due to rich cultural and historical heritage of the town. Collection of spatial data was performed by Time of Flight and phase-shift terrestrial laser scanners in order to derivate high resolution point cloud necessary for derivation of surface model. Split-FX software was used to extract discontinuity surfaces were semi-automatically from the point cloud data. Spatial kinematic analysis was performed for each triangle of TIN surface model of the investigated slopes to identify locations of possible instability mechanism. From the results of the spatial kinematic analysis, the most critical parts of the slope have identified for planar and wedge failure and flexural and block toppling. Verification of identified rock fall areas was performed by visual inspection of hazardous blocks at the surface model. Identified rock fall prone areas, unstable blocks and probable instability mechanisms on the steep slopes above the town Omis, present the input data for risk reduction by efficient design of countermeasures.