Trial to estimate regional characteristics for seismic risk assessment using IKONOS satellite image

The purpose of this study is to develop a method to estimate the quantity of buildings with different seismic vulnerability by using the digital numbers obtained IKONOS. In developing countries, it is difficult to get the building inventory data for seismic risk assessment. In this paper, IKONOS image was chosen for analysis because of its resolution with 1 m and the availability of such data for the major cities in earthquake prone developing countries. IKONOS image of Metro Manila in Philippines was separated into grid cells with 25 m. The pattern of frequency distribution of the digital number for each of four bands subjected to cluster analysis to yield a set of land cover grids with different natural and built environments. We could successfully identify the following different land covers: river, grass, trees, grounds and road, in addition to three kinds of buildings; small, medium, and large. As to the building size of each land cover classification, building inventory stored in GIS data set offered by NAMRIA, Philippines was used to identify the thresholds for different building size.