HAZUS program that introduce uncertainties in its use. For example, HAZUS was originally designed to estimate urban losses primarily from building damage under particular earthquake scenarios. Modules for lifelines, such as transportation, water, and power systems, were added later but still need improvement, especially for estimating the effect losses from one system have on losses in other systems. HAZUS has also been expanded to estimate average annual loss at single locations, but it cannot be used to compute probabilistic aggregate loss for portfolios of properties spread over a large region and cannot take into account insurance variables, such as deductibles and coverage limits.
Requirements for improved loss estimation are driving a broad research agenda to understand the vulnerability of society to earthquakes. This will involve collecting data on the full inventory of vulnerable structures, characterizing the complete range of impacts from earthquake disasters, accurately characterizing the fragility of the built environment, and increasing the accuracy of hazard assessments for the probable earthquake sources. A particularly important issue is how to extend the meth-