The usefulness to rescue teams of nearreal-time loss estimates after major earthquakes is advancing rapidly. The difference in the quality of data available in highly developed compared with developing countries dictates that different approaches be used to maximize mitigation efforts. In developed countries, extensive information from tax and insurance records, together with accurate census figures, furnish detailed data on the fragility of buildings and on the number of people at risk. For example, these data are exploited by the method to estimate losses used in the Hazards U.S. Multi-Hazard (HAZUSMH)software program (httpc//www.fema.gov/plan/prevent/hazus/). However, in developing countries, the population at risk is estimated from inferior data sources and the fragility of the building stock often is derived empirically, using past disastrous earthquakes for calibration .