Evaluation of Vulnerability in Slums and Unformal Residences Against Earthquake (Case Study: Border City of Mashhad)

Abstract

1-INTRODUCTION Iran is one of the vulnerable countries about earthquake issue in the world which is placed in earthquake- belt prone of Himalaya Alp. So it is necessary to identify and evaluate dangerous areas because it can prevent of human and financial losses, when environmental crisis occurs. We did a lot of efforts to decrease and minimum results of earthquake and confident to buildings safety, but slums areas that shaped illegal and spontaneous, control and safety issues don't have legal placed and these areas always have natural, social and economical crisis. Uncontrolled growth of Mashhad city during this decade caused to made narrow streets, locations and small population nuclears inform of illegal and spontaneous in suburbs. There are a lot of out comes in illegal constructions such as non-observance of safety principles in constructions, incorrect usage of structural elements and responsible organization have no control in these areas. The most important purpose of this study is to identify effective factors on vulnerability rate of slum against earthquake. This study is based on physical and vulnerable model in form of internal factors (age of building, kind of building materials, granulation of parts, kind of possession) and external factors (topography, close to fault line, kind of texture, passageways, population density in hectare, household density in residential unit, person density in residential unit) Vulnerable areas identify and finally present for decrease the rate vulnerability procedures caused by earthquake. 2-THEORETICAL FRAMEWORK Environmental risks are a collection of natural, social and economical process so in this study earthquake is considered as a natural risk that has direct and indirect effects in the society. There are 3 general view points: social and economical construction, physical- biology construction and combination construction. In this study theory is based on combination view point that is a collection of natural and human factors and tries to investigate a combination of internal and external variables based on natural, social, and economical. 3-METHODOLOGY This study is analytical- descriptive method with systematic view. The usage model is a physical vulnerable model in form of internal and external and their indicators with use of ARC GIS software and evaluate vulnerability rate of slums areas in Mashhad with AHP model. In this study 1181 number of households in 9 regions of Mashhad slums selected to answer the questions based on Morgan method. 4-DISCUSSION In 9 regions of Mashhad slums are based on physical vulnerability model in form of internal factors (age of building, kind of building materials, granulation of parts, kind of possession) and external factors (topography, close to fault line, kind of texture, passageways, population density in hectare, household density in residential unit, person density in residential unit) and also prepared a vulnerable map with available indicators that showed 70 percent of residences in 9 regions of Mashhad slums are very high vulnerable. So studies show that when the earthquake happen close to fault line, kind of building materials, age of building, person density in residential unit and household density in residential unit are very important in houses vulnerability of Mashhad slums. Results show that 93 percent of Mashhad slums houses are made by long lasting building materials but they didn't have any technical and engineering principles. This subject with non-standard situations elements of urban usage, inefficient communication network, compressed texture, shortage and inappropriate distribution areas of open spaces.etc intensify the vulnerability of residences. 5-CONCLUSION The results showed that residence situation in Mashhad slums are very critical. 93 percent of houses in these areas are made by long lasting building materials but out of engineering principles. These houses will be destroying even by an earthquake with less than 5 Richter scale. The most important solution is to decrease houses vulnerability of Mashhad slums. The first step is to recognize the vulnerable areas and define standards of vulnerability and also to do detailed studies in natural, social, economical fields which are limits of this study. In addition, continuous control to prevent of illegal construction and legal facilities such as: house loan, rebuilding and improving loan for houses that made with no engineering plan are very effective for crisis management.