Estimation of earthquake losses by using macroeconomic approach

Most earthquake loss studies use an inventory approach by which the predict ed damages in various categories of structures and facilities in a concerne d region are estimated and added together to obtain the total estimated. Su ch an approach requires a detailed inventory database of the structures and facilities in the region, which is not always readily available in many re gions of the world. Therefore, an alternative means of estimating earthquak e losses is used based on several macroeconomic indices such as the gross d omestic product (GDP) and population. Based on the published earthquake los s data during 1980-1995, the relations between GDP and earthquake losses ha ve been formulated empirically for several intensity ranges. The world's la nd surface was divided into unit cells with 0.5 degrees x 0.5 degrees in si ze, the GDP of each cell was apportioned based on its population and the GD P and population of the region to which it belongs. The predicted seismic l oss of the cell was then estimated from the seismic hazard probability func tion, its GDP and the empirical relation between GDP and seismic loss. Acco rdingly, a global seismic loss map is compiled. Employing readily available social economic data as the basis for the vulnerability analysis, the meth od enables us to obtain seismic loss estimates for regions without a detail ed inventory of exposed structures or the required collateral geological in formation. Seismic loss estimates can also be upgraded easily with social e conomic data collection for the fast developing areas of the world.