Assessment of global seismic loss based on macroeconomic indicators

Abstract

Most earthquake loss studies use a probabilistic approach in which predicted damages in various categories of structure and facilities in the region in concern are estimated and added together to obtain a total loss for particular intensity ranges. 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. We have used an alternative means of estimating earthquake losses based on several macroeconomic indices such as the gross domestic product and population. Using published earthquake loss data for 1980-1995, the relations between GDP and earthquake loss have been formulated empirically for several intensity ranges. The world's land surface was divided into unit cells 0.5°lat. x 0.5°long. in size. The GDP of each cell was apportioned based on its population and GDP, and the 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. A global seismic loss map is then compiled both for the intensity at 10% probability of exceedance and the probable maximum intensity. Employing readily available socioeconomic data as the basis for the vulnerability analysis, the method enables us to obtain seismic loss estimates for regions without the need for a detailed inventory of exposed structures or collateral geological information. Since such statistics are frequently compiled by the world's leading political and financial institutions, the seismic loss estimates can also be upgraded easily for the fast developing areas of the world.