Rock fall hazard assessment in Asar Hill, ancient Mabolla City, Mugla-SW Turkey

Abstract

This paper discusses the potential rock fall hazard of Asar Hill. This flat-topped hill, containing Upper Miocene conglomerate and finer-grained sedimentary rocks, hosts to the ancient Mabolla City. The seasonal temperature differences are high in this rainy region. Block sizes, bed, and joints attitudes were measured along three profiles during field study. Schmidt Hammer was applied to grains and matrix of conglomerates for determining strength in situ. One joint set in Profile A, 3 in Profile B, and 4 in Profile C were determined via dips analysis. An intersection of joints and bedding (directed 25 degrees-35 degrees NW) caused the block formation, control slope, angle and mass movement type. At least 10 blocks (0.6-1241.085 tons) were fixed on top of profiles. Two blocks on top of the eastern Profile A contain archaeological ruins. After back analysis for determining restitution coefficients, RocFall version 4.9 software program was used to determine possible end points of those blocks. Most of the blocks can reach the valley and pass the other side, which includes settlements and gardens. Consequently the possible rock fall hazard in Asar hill is threatening visitors and settlers. The cleaning of detached blocks on top of slope is one of the easiest ways. However, in situ preservation of blocks with archaeological ruins via tensioned rock anchors and/or patterned rock bolts has vital importance. Relocation of settlers and gardens, opening trench around hill, and establishing green belt-forest would be considered as other measures.