More than 100 representatives from academia, the private sector, non-governmental organizations, and local, State, and Federal government participated, offering diverse perspectives on natural disasters and on the links between natural hazards and other urban issues. The World's population has rapidly urbanized during this century, for technological, social and political reasons. Cities now depend on the functioning and interaction of complex social, political and engineering systems, many of which are not well understood and all of which are subject to disruption by natural disaster. We are only beginning to comprehend these vulnerabilities and their implications for disaster mitigation, for emergency management, and for disaster recovery. Challenges of natural disaster risk in cities and megacities Today's cities and megacities are unlike any that existed in the past, and thus we cannot expect our experience with historical disasters to guide us in the future.
Cities are larger than ever before and growing in size at an unprecedented rate.
The average population of the world's 100 largest cities has swelled from 700,000 in 1900 to 5 million in 1990. Furthermore, as cities have grown, they have often expanded onto hazardous lands. For various reasons, people are choosing to live in harm's way. New threats have arisen as the megacities have grown. The combination of natural and technological hazards creates an environment in which effects may be multiplied through cascading multi-disasters.