Structural, geomorphological and geomechanical aspects of the Koyulhisar landslides in the North Anatolian Fault Zone (Sivas, Turkey)

Abstract

Recently, numerous landslides occurred in the northern part of Koyulhisar. In 1998 and 2000, which were very wet years, landslides in different masses affected the geological formations which are well known for being prone to slope movements. Detailed geological, geomorphological and geotechnical surveys were carried out, and stability conditions in Koyulhisar village, located NE of Sivas (Turkey), are discussed in this paper. Kinematical analyses showed that the potential slope instabilities are in two main directions: the first direction is SE and the second is SW, these directions corresponding to the dominant slope directions of the study area. Geomechanic surveys confirmed that most of the rock slopes analysed are highly prone to instability. The SMR criterion gave results which correspond well with real stability conditions. Jointing and faulting, steep topography, water incisions, and heavy rainfall played a significant role in the occurrence of the landslides.