Analysis of urban fabric vulnerability against earthquake. (Case study: Tehran,District 2).

Abstract
Despite of the social - economic development systems and urbanization, people are increasingly suffering from the effects of natural disasters. Earthquak is one of the major natural disasters that cause damage to building and urban infrastructure. So, Vulnerable areas of the cities are areas that we can with identify, zoning and policy making, reducing the negative effects brought about by the disaster. The present study was included in two parts: descriptive and analytical. The descriptive section of the library and documentation in accordance with the criteria selected and Three indicators of physical, social and environmental are considered and criteria for each of the parameters are considered. descriptive data were collected and the analytical models used. In this study to determine the seismic vulnerability of the region to be used in the model ANP and Fuzzy. After obtaining the weight of each criteria set by the model ANP, Fuzzy techniques for the integration layer is used. The results indicate that, urban Fabric vulnerability at District 2 is high and this rate in southern and east regions according to the results of fuzzy techniques is much higher.
Introduction
In our times with the development of social-economic systems ,and urbanization, earthquake is one of the major natural hazards Cause damage to buildings and urban infrastructure. During the twentieth century, growth population cause for the construction of settlements in high risk areas. A large number of the population will settle in big. Many of the major cities have been at or near the active faults. Thus, the‌ vulnerability of cities, especially in urban contexts in developing countries is a serious examination of the earthquake. Hence, the study of earthquakes in urban areas is also important, not only for developing countries but also in developed. Among these, Tehran as a metropolis in recent decades has a growing and increasingly irregular and non-homogeneous led to tissues is of non-standard. Despite the increase in construction in some areas of the districts2 of Tehran, Due to the high price of land has developmed rapidly and had a high density. The District 2, have a population of over 321,496 thousand. Much of the area due to the rapid construction in the past two decades. On the other hand the existence of faults in the vicinity and within this range, the region's vulnerability to natural disasters is increasing. Hence it is necessary to identify the fabric vulnerable to serious remedy to reduce vulnerability to earthquakes take place in urban contexts. Thus, the need to attention this region as one of the most vulnerable areas of Tehran.
Methodology
This study include of two parts of , descriptive and analytical that the section of descriptive with using the library and archival research objective selection criteria in accordance with the descriptive data has been collected. The analytic model in this study to determine the seismic vulnerability of the region to be used in the model ANP and Fuzzy. One of the common methods of multi-criteria decision making process of network analysis ANP. Model, analytic network process ANP complex relationships between and among elements of the decision through the replacement of hierarchical network architecture into consideration. In this study, the the effectiveness criteria identify and were defined and for The rating criteria for each study, the questionnaire was designed to get the opinions of experts (30 experts) were recorded Tables that The criteria for determining the value and importance of the approach ANP to calculate the weights of the criteria. After obtaining the weight of each criteria set by the model ANP, technique, Fuzzy and to combine layers of spatial analysis and GIS, is used and Finally, vulnerable areas in the study area has been provided.
Discussion
Identify and prioritize effective criteria of the vulnerability of urban planning and appropriate corrective actions in these tissues is particular importance to during the incident. Therefore, in this study, the indicators in the areas of environmental, physical and social chosen the following set of criteria considered, and for The rating criteria for each study, the questionnaire was designed And to get expert opinions, the tables have been recorded and used to determine the value and importance of the criteria by ANP method to calculate the weights of the criteria we have discussed. In this study Eleven criteria have been considered. After entering the inputs to the software SuperDecision the final weight is obtained by set criteria. In this study, in order to attain the purpose of and to characterize the vulnerability of urban used of Spatial Integration of GIS techniques GIS and fuzzy operators. criteria through ANP has weighted and For each criterion, the layers are prepared and then The criteria in GIS environment using appropriate fuzzy operators (gamma), fuzzy membership to have received. Through the appropriate digital layer on the investment criteria established by each layer, and the digital layer of vulnerable zones in the study area are shown.
Conclusion
The values in the standardization of map layers and the weight of each layer is considered zero to one. Whatever the number is closer to one indicative of a greater utility and desirability of any size is closer to zero, it will be reduced. As you can seen in the map, Amount of pixels that are closer to dark spaces have value of zero and reduced from space utility And urban fabric have high vulnerability, Conversely, pixels that have been gray and white colors Values are more And the vulnerability index have more desirable. With a little reflection on the current situation can be found in the map, the majority of the district 2 have moderate vulnerability that In the meantime, the eastern half, both South and North-West district 2 of Tehran Municipality due to high density residential population has a high vulnerability. The central part of the urban area due to the lack of open spaces and bright colors of certain users are more desirable.


Keywords:Analysis, vulnerability, urban, fabric, earthquake.