Landslide is a serious problem in the mountainous region of western, Zagros mountains and northern, Alborz mountains of Iran. Every year tens of landslides occur in these areas of Iran. They case enormous economic damages and the losses life annually. This paper presents the landslide hazard and the major factors influencing on the movement of landslide in mountainous area of Iran. Many of landslides are reactivated and have been triggered by human activity although always related to period of continued rainfall or other accelerated phenomena such as earthquake. Construction of building, slope cutting, road building, and deforestation are important causes of failure hazards. Geological, geotechnical, geomorphological, weathering, and hydrogeological conditions are the critical among the natural factors

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