Estimation of earthquake losses by using macroeconomic approach

Most earthquake loss studies use an inventory approach by which the predicted damages in various categories of structures and facilities in a concerned region are estimated and added together to obtain the total estimated. Such an approach requires a detailed inventory database of the structures and facilities in the region, which is not always readily available in many regions of the world. Therefore, an alternative means of estimating earthquake losses is used based on several macroeconomic indices such as the gross domestic product (GDP) and population. Based on the published earthquake loss data during 1980–1995, the relations between GDP and earthquake losses have been formulated empirically for several intensity ranges. The world’s land surface was divided into unit cells with 0.5° × 0.5° in size, the GDP of each cell was apportioned based on its population and the GDP and population of the region to which it belongs. The predicted seismic loss of the cell was then estimated from the seismic hazard probability function, its GDP and the empirical relation between GDP and seismic loss. Accordingly, a global seismic loss map is compiled. Employing readily available social economic data as the basis for the vulnerability analysis, the method enables us to obtain seismic loss estimates for regions without a detailed inventory of exposed structures or the required collateral geological information. Seismic loss estimates can also be upgraded easily with social economic data collection for the fast developing areas of the world.