Özet:
Cappadocia is one of the most important natural, historical and cultural heritages
of Turkey. The region is seriously threatened by different instability problems, and
several locations were accordingly closed to visit, mainly because of rockfalls. The aim of
current study is to investigate the rockfall hazard potential near the Tatlarin Underground
City. For this purpose, an extensive engineering geological investigation was performed
and complemented with a set of rockfall simulations performed by means of the 3D
numerical model HY-STONE. The investigation included: (1) mapping of the lithological
units (tuffs and overlying basalts, talus deposits) and of unstable blocks along the cliff; (2)
rock mass geomechanics and kinematic analysis of block stability; and (3) laboratory
testing of tuff and basalt. These allowed to show that the instabilities are mainly controlled
by different durability of tuffs and basalts. The weakness of tuffs facilitates a progressive
undercutting of the basalt layer, the opening of subvertical joints and the consequent
movement of large basaltic blocks. Two future potential rockfall scenarios have been
produced by 3D rockfall modelling for hazard zonation and for suggesting risk management
strategies. Model parameters were calibrated by back-analysis of both historical
events and field tests. Different sets of parameters have been calibrated for different release
volumes to consider different degrees of interaction with slope material of different size.
The effect of roughness of the topography was investigated in terms of trajectories and
lateral dispersion of blocks and its consequences on hazard zonation and risk management
actions.