GIS based landslide susceptibility analysis of an area (Niksar-Suşehri) on North Anatolian fault zone

In this study, landslide susceptibility assessment of the 1445 km2 area in the Kelkit River valley including southeast of Niksar, Reşadiye, Koyulhisar, northwest of Suşehri and its surroundings was carried out by statistical methods. In the study, 1/25.000 scale geological maps and topographical maps were used as basic data group. Landslide inventory maps were prepared by using landslide data determined by field surveys and landslide data taken from General Directorate of Mineral Research and Exploration. Lithology classes were obtained by digitizing geological data; and elevation, slope, and aspect data were produced from digitized topographical data. Distance to the fault, distance to road, distance to streams, drainage density and fault density data were obtained by using topographic data. These data were evaluates with frequency ratio, logistic regression and fuzzy logic methods and sensitive areas by the landslide point of view were determined, and landslide susceptibility maps were obtained. Landslide susceptibility maps were divided into five susceptibility regions as very low, low, moderate, high and very high. By using frequency ratio, fuzzy logic and logistic regression methods; 68 %, 59 % and 53 % of the landslide areas in the study area D1 were detected as highly or very highly susceptible classes, respectively. Same percents were 79 %, 72 % and 61 % for the study area D2. Based on these data; it is concluded that produced susceptibility maps are usable, and the frequency ratio method has given most reasonable and true results.