Cities in the 21st century

Internationally, Cities in the 21st century are facing wide range of increasing risks which could be natural or man-made hazards. The scale of urban risk is increasing due to complexity of city systems and the rapid urbanization which leads to the growth of the impacts of uncertain risks that may suddenly occur. These risks are divided into two types first are shocks which happens suddenly and unexpectedly like earthquakes, fires, and floods, tsunamis and natural disasters second are stresses that continuously weaken cities on a daily basis. These stresses might be high unemployment, terrorism, an inefficient public transportation system, economic crises, and food and water shortages.