Prevalence of Non-Engineered Buildings and Population at Risk for a Probable Earthquake: A Cross-Sectional Study from an Informal Settlement in Tehran, Iran

BACKGROUND: Constructions in informal settlements not respected any applying rules, regulations of urban planning, and building codes with high population density, are the municipality challenge. We aimed to identify level of buildings seismic vulnerability and population at risk in Tehran’s Farahzad informal settlement in 2017. METHODS: In this observational cross-sectional study, residential buildings were assessed for seismic performance of constructions. We screened 160 buildings according to Iranian national guidelines by Rapid Seismic Visual Screening Method as a tool to calculate and determine Level of Retrofitting (L(R)) scores of buildings. We also interviewed residents of the buildings to collect data regarding socio-demographic data, individual disability status, Disaster Assessment of Readiness and Training (DART) regarding household disaster preparedness, and time occupancy in the buildings. RESULTS: Overall, 160 buildings with 209 households and 957 individuals were surveyed. 97.5% of buildings were formed of heavy construction materials. None of them were categorized as engineered buildings and L(R) of residential buildings ranged from 82.4% to 163.8% with a mean 117.9%. L(R) scores of more than 100% were capped as 100%. Vulnerable groups of the sample population include under-five years old (8.7%), 60 yr old and above (6.7%), and 9.1% of households had at least one disabled member. 16.7% of households were living in homes with dense area. The DART score for 94.3% of surveyed households was zero. CONCLUSION: Disaster managers in Tehran municipality must design and implement a comprehensive risk reduction plan in poor urban areas as vulnerable regions for earthquake hazard.