Landslide Hazard Zonation in QeshmIsland

Persian Gulf's largest island, Qeshmis located in north-west of the Strait ofHormuz. Earthquakes of 27 November, 2005 (Mb=6) and 10 September, 2008 (Mb=6.2), causing 10 and 7 casualties respectively, destroying many villages and triggering numerous slope instabilities, revealed the need for a comprehensive study on development of safe construction more than ever. One of these studies could be on landslides, using its results could be considered for reducing damages and injuries during upcoming earthquakes. To achieve this goal, landslide hazard zonation of Qeshm has been studied. In this regard, the type of slope instability and its factors were identified, using the aerial photographs, satellite images and field surveys; showing that the most abundant type of landslide in the region is rock fall. In the next step, maps of landslide factors were prepared, and then by using and modifying Anbalagan methodology, landslide hazard zonation map was prepared. In addition to the above-mentioned method the fuzzy logic theory is also applied in order to achieve more accurate results and to investigate the effects of weighting method on the conducted zonation. Assessing and comparing the results of the zonations are carried out calculating the Quality Sum (QS) for each method. Comparing the results shows almost equal values. Concerning the equal situation and according to the obtained results (QS), it can be said that the appropriate selection of affecting factors on slope instability is more important than the simplicity or complexity of weighting methods.