Geo-spatial Approach for Likelihood Damage Assessment of Buildings Due to Seismic Hazard in Urbanized Areas

Abstract

Earthquake damage assessment studies in urban cities are one of the leading problems because dense population is located in a small area. So, the study of damage probability of the buildings due to earthquakes particularly in urban cities have main focus, since it may end up brutal economic damage. The Chennai city, which is head quarters of Tamil Nadu state in Southern part of India, is an urbanized area, and it is categorized as fourth densely populated city in the country. The Chennai city is classified under moderate Seismic Hazard Zone (Zone III) by Bureau of Indian Standard. In this connection, a study has been carried out to understand the seismic vulnerability of the buildings in the Chennai city using geo-spatial techniques. FEMA 154 rapid visual screening methodology, which is modified suiting to Indian conditions, is used for the present study to assess the vulnerability in the built-up areas of the Chennai city, India. A foot print map was prepared for the part of Chennai city by visual interpretation and limited ground truth verification. Visual survey also carried out for sample buildings in the study area. Based on the survey, database is created in GIS platform for the different parameters, viz. age of the building, soil type, year of construction, number of stories, irregularities in the building, etc., for 2585 buildings. Based on the damage, probability for Magnitude 6.9 Score values was derived and the buildings in the areas classified from Grade 5 (high-probability damage) to Grade 1 (low-probability damage). Based on the study, totally 93% of buildings in the study area meet the earthquake resistance capability, and 7% of the buildings need further detailed structural evaluation for earthquake resistance. This study can be used as first-hand information for the researchers and administrators involved in earthquake emergency planning and decision making for Chennai city.