Disaster casualties – accounting for economic impacts and diurnal variation

Abstract

While some progress is being made in the reduction of losses due to natural hazards such as earthquakes, more progress is needed. Casualty and economic loss trends for the twentieth century are first examined. As opposed to widely publicised claims of rapidly increasing loss trends, we find decreasing trends for both casualties and losses, when population growth and urbanisation are accounted for. In order to provide a single measure of the significance of disasters, the concept of Economic Adjusted Life Years (EALY) is introduced, which extends Disability Adjusted Life Years (DALY) as used in the health field to include economic costs of disasters. EALYs are calculated for a number of major twentieth century earthquakes, finding that millions of years of human productivity have been lost in these events. This equates to, case-by-case, setting back a particular group years to decades in its development. Lastly, the temporal patterns of twentieth century earthquake fatalities are examined, finding a significant diurnal variation. That is, earthquakes that occur at night have relatively more fatalities than they would if they occurred in daylight. Without accounting for diurnal variation, mortality and morbidity estimates can be off by a factor of as much as ± 34%.