Zoning the Landslide Hazard and its Impact on Instability of Urban Settlements Case Study: Gorgan Zybashhr

Instablity of side hills specially the risk of land slide are the main hazards in sloped area with loose soil and usually have high frequency. The hill area of Ziba shahr in Gorgan،due to the spread of Loose hills and Low resistance soil، also، changing sloped areas into residential areas and construction and civil activities on gable roofs in order to establish road، building and etc. has particular sensitivity against risk of land slide. In this study، it is tried to investigate about the effective factors on the instability of the area by emphasizing on geomorphology. Data used in this study are، topography and Geology maps، land uses، Gorgan urban map، satellite images together with field visit. Analysis method، on the basis of the existing data is apriority. for data analysis، the relevant maps transferred to GIS area and by using AHP model، the risk of land slide in area was evaluated. Totally 8 main criteria related to land slide phenomenon were analyzed، these criteria were classified as separate map factor and were valued by Statistical methods and consult with experts. Final produced map in area showed that، slop factor 15. 8 percent، geology and soil flexibility 28 percent، fault 14 percent and land use 12. 3 had the most effect on land slide in area. So the area is instable and avoiding of danger limitation is optimized.