Risk management strategies for managing natural disaster risks: A case study in Shiraz City, Iran

Almost all parts of Iran are seismic hazard prone areas and due to the low quality of constructions as well the increase of exposure in urban areas, recent earthquake events caused unacceptable huge losses, both in human and economic terms. To assess the resilience of various risk bearers, including the government as well as private sector entities, the resources to cope with potential future events as well as possible interdependencies during the occurrence have to be analyzed in detail. Furthermore, to pro-actively act against possible future extremes with risk hedging instruments such as insurance, the underlying risk has to be determined in quantitative manner. This paper suggest how to combine both, the coping dimension as well as the risk dimension, to determine possible risk management strategies which may be feasible in the Iranian context. The focus is specifically on risk instruments, such as insurance, for the Shiraz region in Iran, where the newly produced probabilistic loss estimates are available which are subsequently used to analyze possible insurance schemes and for determining corresponding premium payments as well as affordability. The paper discusses how such risk instruments can be embedded within an integrated framework and which additional options, such as risk reduction or risk pooling, would be beneficial to lower premiums to affordable levels

Physical Resilience of the Electricity Transmission Grid against Earthquake: Analysis of a Prototype Model

Increasing number of power supply interruptions due to earthquakes leads to heavy direct and indirect economic losses and indicates the importance of resilience of electric power networks. The present study, focusing on seismic resilience of the electricity transmission grid, is looking to develop a basic framework for calculating power grid performance and resilience. This research, based on the network performance analysis and the graph theory, is using a prototype model of the electricity transmission grid to calculate the average performance of the system over recovery time, as the system resilience. This research distinguishes between the damaged facilities in the network by classifying damage levels to different degrees between zero and one and assigning performance values to each level to go beyond the binary statement of connectivity analysis, while having fast and simple calculations

Seismic hazard assessment of Iran

The development of the new seismic hazard map of Iran is based on probabilistic seismic hazard computation using the historical earthquakes data, geology, tectonics, fault activity and seismic source models in Iran. These maps have been prepared to indicate the earthquake hazard of Iran in the form of iso-acceleration contour lines, and seismic hazard zoning, by using current probabilistic procedures. They display the probabilistic estimates of Peak Ground Acceleration (PGA) for the return periods of 75 and 475 years. The maps have been divided into intervals of 0.25 degrees in both latitudinal and longitudinal directions to calculate the peak ground acceleration values at each grid point and draw the seismic hazard curves. The results presented in this study will provide the basis for the preparation of seismic risk maps, the estimation of earthquake insurance premiums, and the preliminary site evaluation of critical facilities

Seismic hazard assessment of Iran

The development of the new seismic hazard map of Iran is based on probabilistic seismic hazard computation using the historical earthquakes data, geology, tectonics, fault activity and seismic source models in Iran. These maps have been prepared to indicate the earthquake hazard of Iran in the form of iso-acceleration contour lines, and seismic hazard zoning, by using current probabilistic procedures. They display the probabilistic estimates of Peak Ground Acceleration (PGA) for the return periods of 75 and 475 years. The maps have been divided into intervals of 0.25 degrees in both latitudinal and longitudinal directions to calculate the peak ground acceleration values at each grid point and draw the seismic hazard curves. The results presented in this study will provide the basis for the preparation of seismic risk maps, the estimation of earthquake insurance premiums, and the preliminary site evaluation of critical facilities

Evaluation of earthquake mitigation measures to reduce economic and human losses: a case study to residential property owners in the metropolitan area of Shiraz, Iran

Iran is located in a highly seismic active region, and building structures, therefore, need to be designed and constructed to withstand major earthquakes. Structural mitigation measures are now seen as one key element to reduce economic as well as human losses for today and in the future. However, the costs and benefits of various options are difficult to be assessed and usually done without considering both human and economic aspects. This paper should fill part of this gap and performs an in-depth earthquake risk analysis for Shiraz city, in Iran. Additionally, the effects of different mitigation measures for buildings and corresponding changes in risk levels have been investigated. Probabilistic seismic hazard analysis is used to prepare the hazard curves, to be used in the probabilistic cost-benefit analysis of buildings to investigate the effects of using different strengthening strategies. Regarding the importance of the assessment of human casualties during earthquakes, additional cost-benefit ratios were calculated by considering the value of statistical life and performing sensitivity analysis. The results show that considering the value of statistical life in cost-benefit analysis can significantly increase the structural cost-benefit ratios. This has impotant implications for the decision support as well as policy making side in Iran, and we conclude with suggestions how these issues could be addressed in the future using a risk-layering approach

Seismic Failure Probability of a Curved Bridge Based on Analytical and Neural Network Approaches

This study focuses on seismic fragility assessment of horizontal curved bridge, which has been derived by neural network prediction. The objective is the optimization of structural responses of metaheuristic solutions. A regression model for the responses of the horizontal curved bridge with variable coefficients is built in the neural networks simulation environment based on the existing NTHA data. In order to achieve accurate results in a neural network, 1677 seismic analysis was performed in OpenSees. To achieve better performance of neural network and reduce the dimensionality of input data, dimensionality reduction techniques such as factor analysis approach were applied. Different types of neural network training algorithm were used and the best algorithm was adopted. The developed ANN approach is then used to verify the fragility curves of NTHA. The obtained results indicated that neural network approach could be used for predicting the seismic behavior of bridge elements and fragility, with enough feature extraction of ground motion records and response of structure according to the statistical works. Fragility curves extracted from the two approaches generally show proper compliance