Anthropogenetically triggered landslide factors of the Varyant landslide area at Buyukcekmece, NW Turkey

Abstract

Since early 1950s many natural conditioning factors and interference have given rise to landslides near heavily populated settlement areas at the western part of Istanbul, NW of Turkey. Both human involvement and heavy rainfall have a great impact as triggering factors over the Varyant landslide area (VLA). The onset of the landslide activity ill VLA began in 1950's after the construction of E-5 motorway, at the east of Buyukcekmece Lake. A linkage way to E-5 motorway was built near the drainage divide of Cakmakli Creek catchment has already been causing some disturbance to the slope stability. Excavation activities were carried out in order to get materials for building of the Buyukcekmece Dam, do form one of the important drinking water sources of Istanbul. A great amount of materials were derived from the accumulation zone of the above-mentioned old landslide area with nearly 1 km length and the excavations heightened the slope failures. Following the construction of the Buyukcekmece Dam in 1989, a water pipe-line was installed within a landslide body, resulted in some new slope movements. Finally, a pipe-line-induced destructive landslide occurred on 2(nd) February 2000, causing a great economic damage of nearly US $ 5.5 million.