Spatial Analysis of Vulnerable Areas during the Human Crisis with an Emphasis on Passive Defense in Tabriz Urban Infrastructures

Introduction
Security has always been one of the most important issues facing human beings. Throughout history, man has sought to have security through various defending instruments. This defense has two types including military and civil defense called respectively, active defense and passive defense.
Passive defense is a strategic plan requiring direct management and planning of expert human forces including instruments, enginery, organization, training, and management of forces (Taghvayi and Jozi Khamselouyi, 2012:17).
Considering the high volume of capitalization and establishment of many installations as well as economic tools and most importantly, high population residences, cities have significant financial and bodily vulnerabilities in case of the outbreak of war.
Due to its strategic status, Tabriz city, as a metropolitan in the northwest part of Iran, faces various human threats. This city is one of the five regions of Iran facing ethnic regionalism (Mohammadi et al., 2008:60). According to the geographical, geopolitical, political, and economic conditions of Tabriz, it has been sometimes recognized as the economic center of Iran, and sometimes at least in the north-west region of the country (currently), it has been identified as the first pole of industry, trading, and commerce (GHorbani, 2003:123). The existence of important economic, military and political centers has made the discussion of the passive defense subject of this city an important issue.
Data and Method
The purposeful article was developmental-applied in terms of policy-making, and it was analytical-descriptive in terms of the design of the study. To collect the literature of the subject and theories of the study, library and documentary method was utilized. Moreover, Arc Gis, version 10, software was used to analyze the data and provide the required maps, which had an important role in the advancement of the study after collecting various layers since they showed different terms. Among the most important utilized criteria and indexes for the analysis, urban electrical substation privacies, urban gas pressure reduction substation privacies (Siami et al., 2013:31), gas and petrol station privacies (Valipour et al., 2014:174), military center privacies, distance from hospitals, distance from main streets (Pour Mohammadi et al., 2010:111), water sources privacies (Ministry of energy, 2014:161), distance from firefighting centers (Azizim Bornafar, 2012:132) and distance from open and green spaces (Razavian, 2002:142) could be highlighted.
 
Results and Discussion
Having accomplished the standardization of layers, their integration was the second part of the research. To this end, and for determining their importance and the weight of each layer, a hierarchal analysis method was utilized for such samples whose criteria number was high. The target Expert Choice hierarchal analysis model was determined in specific software and the final weight of each layer was calculated. As the weight of each layer was obtained, they were integrated using GIS, thus the final map of vulnerability status was shown.
The results of zoning indicated that some parts of Tabriz city, especially regions from the center of the city to the eastern parts and northern parts, were the most suburbanite fabrics of the city and had higher densities; moreover, some of the newer fabrics in the western parts of the city had higher vulnerabilities. Besides, moderate and high vulnerabilities could be observed around the main streets of the city and highroads due to the importance of these infrastructures and the establishment of other related infrastructures related to transportation services. 
Conclusion
The results of this study were somehow in line with the studies conducted by Siami et al., (2013) since both of the studies showed that regions having high population densities that needed various infrastructures had high vulnerabilities. Moreover, the hierarchal analysis method indicated that the vulnerability of infrastructures in Tabriz included respectively, military centers, electronic, telecommunication, streets, gas, and hospital infrastructures.  
Besides, having a view on the population and building density map and their adjustment with the vulnerability of infrastructures, it could be stated that most of the areas having high vulnerability were located in these overgrown regions, thus, the populated regions would have more vulnerability in crisis time; this fact makes the subject of crisis management and serving an important issue. In central parts of the city, the vulnerability was low due to the lack of vital installations (lack of empty lands), however, the vulnerability of infrastructures was high in suburbanite regions.