Vulnerability is the limitation of a society to a risk and to dominate it for all physical, economic, social and political factors, which adversely affects the ability of the community to respond to those events. An earthquake is a natural phenomenon that will be irreversibly damaged. It has caused severe humanitarian earthquakes in the minds of a compilation of an infrastructure program to reduce the risks and damage caused by it. The country's geostationary characteristics have suggested earthquakes as one of the most destructive factors in the destruction of human life. Historical surveys show that vast areas of our country suffered financial and financial losses due to this natural disaster. According to the United Nations, in 2003, Iran ranked first in the number of earthquakes with a high intensity of 5.5 millimeters among the countries of the world.Earthquake is a natural hazard that often causes too many losses and casualties. Iran is country with a lot of earthquakes and and Khorasan Razavi province which is studied in this study also experiences a large number of this natural hazard and 71% of the surface area of this province is in the range of medium, high and too high hazard of earthquake. One of the important sectors in which the effect of the earthquake damage very large is power transmission lines. Transmission of oil and gas products by pipelines is one of the most appropriate, inexpensive, fast and reliable methods. These lines are mostly buried in terms of safety and social considerations. In engineering collections, such structures are considered as vital arteries. Due to the fact that pipelines are spreading widely, therefore, due to the vulnerability of the transmission lines, it can damage the economy of the country.
In this study the vulnerability of the network lines of power transmission of Khorasan Razavi province against earthquake were studied. The aim of the present study was applicable and method of study was descriptive-analytic. To prepare a map of the extent of the vulnerability, the fuzzy gamma method was used. Effective parameters for this research include proximity to a fault line, geological structure, land slope, population density of urban and rural areas, distance from the communication lines. One of the most important fuzzy operators for overlapping indices is the GAMMA operator. Gamma operator is the general mode of multiplication and addition operators.