Urban planning that can be defined as designing the cities according to the foresights for the future has undergone major changes with exposure of urban areas to major disasters for last 50 years. It is agreed that the most important factor of making disaster resilient city is taking precautions and damage reduction with planning process. In Turkey, disaster sensitive planning approach which started quite late and after the great losses has largely taken place right after the major earthquake occurring in 1999. Thus, the transition from period of transferring disaster hazards to the planning through the synthesis of thresholds to period that geological, geotechnical and microzonation reports are compulsory has been experienced. Making geological surveys in various forms in order to be basis for planning activities in every scale has been obliged by the laws. The outputs of these different analyzes filled reports providing inputs for planning are the site suitability maps which classify settlements in four categories: appropriate areas for settlement, areas for preventive actions, areas require detailed geotechnical survey and inappropriate areas for settlement. Empirical studies show that although microzonation studies have been currently undertaken, plan decisions based on residential areas are quite poor due to the challenges of restricting the development rights, regulating and discharging of those areas. This study aims to examine conformity of planning decisions and existing urban patterns with the site suitability maps produced by microzonation studies in the İstanbul, megacity of Turkey.