Seismic damage to urban areas due to failed buried fuel pipelines case study: fire following earthquake in the city of Kermanshah, Iran

Abstract

Oil Pipeline and Telecommunication Company of West Region is one of the eleven regional branches of Iranian Oil Pipeline and Telecommunication Companies (IOPTC) and is responsible for the transfer of crude oil and oil products through 129, 236, and 179 km pipelines in the western region of Iran in the provinces of Kermanshah, Kurdestan, and Ilam and Lorestan, respectively. This paper, in respect of damage analysis, concentrates on the assessment of fuel pipeline systems buried underneath the city of Kermanshah, failure in pipelines and post-earthquake fires. In order to assess the seismic damage to buried fuel pipelines of Kermanshah with the help of characteristics and information of network components, PGA and PGV values are initially determined for two probable earthquake scenarios in the study area, using the attenuation relations derived for the same area. Then, using the repair rate relations, damage to pipelines is estimated. Furthermore, the consequences of the release of oil materials from the pipelines and their ignition are analyzed using the logic tree. The probability distribution function for the area, the population, and the number of houses exposed to fire and explosion after the earthquake are calculated using the Monte Carlo simulation method through numerous repetitions (10,000 times). All the steps of damage assessment for buried pipelines were written in a GIS environment. Two proposed mitigation strategies for fire damage reduction in the Kermanshah area are investigated in the second stage, and the damage is investigated by repeating the process. In order to give a better description of the output results, the probability distribution functions for each output are provided. In summary, the damage inflicted on the fuel pipelines of Kermanshah is equal to 17 leaks, 5 breaks, and 21 ignitions for earthquake scenario 1, which was reduced to 2 ignitions after mitigation strategy 1. Comparing mitigation strategies 1 and 2 in earthquake scenario 1, it is concluded that although the ratio of assumed reduction of ignition probabilities of strategy 2 to strategy 1 is 0.5, the relative reductions gained in the strategy 2 are 78.95, 75.98, 83.83, and 78.90 % with respect to strategy 1 for number of ignitions, affected area, number of fatalities, and number of buildings exposed to explosion, respectively. The proposed method could be used in other similar cases and also as a platform for further supplementary analyses.