Risk management in Human made crises with passive defense approach (Case study: Tehran)

That is important today is very important in the urban system, The ability of this system utilizes principles of passive defense system and respond to external expectations, This awareness that urban planners and designers in creating healthy and safe urban demand. In this study, the metropolis of Tehran, the largest and most important city in the country chosen according to research topic was chosen due to the combination of foundation Descriptive, Analytical and Case. That in order to classify and analyze the information HAZOP model is used, which is an appropriate model for risk management. The results of the HAZOP model indicate that the most catastrophic war and attack the enemy and terrorism are threats in urban environments That such threats can be greatly reduced risk of catastrophic damage they. Strike, riot, vandalism and false information in order of importance are the next category, Risk Management The threats to new types of threats can be largely and almost completely controlled. And according to what was stated, it can be concluded that in the current situation in Tehran is seen as a strategy, as a result of the actions of the enemy, the city's infrastructure is disrupted. Subsequently, the major problems arise. As a result, the starting point for many economic activities, social and political crisis interrupted the activities of people, authorities and even the defenders of the city changes.