Assessment of Overall Resilience Index of Urban Areas against Earthquake considering Intra- and Interdependencies between Different Sectors

Sustainability and resiliency analysis of cities is not completed without considering the whole system of interacting sectors. The purpose of this study is to introduce an algorithm for assessment of overall seismic resiliency increase of urban areas due to the reduction of Intra- and Interdependencies between different sectors and retrofitting infrastructures. The proposed method is versatile, and different dimensions of resiliency, i.e., social, economic, technical, physical, institutional, and security dimensions of resiliency are considered in the study. In this research, the technical dimension, i.e., the functionality of water and power networks are modeled as an example, and some solutions to increase overall resiliency of an urban district against earthquake is investigated. The algorithm is based on the inoperability input-output model, and the interaction between water and power sectors in a metropolitan district is surveyed. Based on the results of a number of Monte Carlo simulations of different dependency scenarios, it is quantitatively shown that the decrease in interdependency has a direct and great effect on the increase in serviceability and overall resiliency indices, but the pattern of this effect is different between various earthquake scenarios. It is concluded that the reduction of interdependency has an increasing effect on the overall resiliency index. Thus, an optimum value for interdependency reduction can be obtained to increase resiliency index using the Pareto principle, and the influence of reducing of interdependency on increasing the resiliency of a region as a whole is investigated. The proposed model may be used in system analysis for other dependent sectors and for different disasters and can also be considered as a helpful measure for decision-makers in sustainability and resiliency enhancement studies.