A new hybrid model for emergency location problem after earthquake in Mashhad

Earthquakes can cause significant disruption and devastation in communities. Especially, Iran is one of the countries with the most natural hazards, while earthquake causes most of casualties in this country for several reasons including the inappropriate construction methods, the improper physical growth and the lack of minimum necessary requirement. Mashhad is a city located in the northeast of Iran, the center and capital of Razavi Khorasan Province and the second largest populated city after Tehran. This city because of the high-density housing and the absence of urban development plans in worn-out context is facing a more serious risk. In this study a new hybrid method has been proposed for emergency location problem. First, a system dynamics model for the urban has been used to estimate the number of damaged buildings by focusing on construction and population subsystems. Second, the number of earthquake casualty has been estimated by the casualty estimation model of Coburn and Spence, while the output of system dynamics model is the most important inputs of this model. This method is implemented for different possible earthquake scenarios in Mashhad. Each scenario has been defined based on the length of active fault, the acceleration of activity and the greatness of the quake. Third, the Geographical Information System (GIS) has been used to specify the potential emergency location centers to cover the population. Finally, the location allocation model has been presented to locate the emergency location centers cover the survivors. The results of this hybrid model showed that we need at most 231 emergengency locations in the worst case and the minimum needed locations is 93.