NOTICE: The project that is the subject of this report was approved by the Governing Board of the National Research Council, whose members are drawn from the councils of the National Academy of Sciences, the National Academy of Engineering, and the Institute of Medicine. The members of the steering committee responsible for the report were chosen for their special competences and with regard for appropriate balance.

This report has been reviewed by a group other than the authors according to procedures approved by a Report Review Committee consisting of members of the National Academy of Sciences, the National Academy of Engineering, and the Institute of Medicine .

Support for this project was provided by the Department of the Navy, Office of the Chief of Naval Research, under grant number N00014-93-1-0166. The project was conducted at the request of the Department of Defense, Defense Advanced Research Projects Agency. The content of this workshop report does not necessarily reflect the position or the policy of the federal government, and no official endorsement should be inferred.

On the cover: A photograph provided by the Federal Emergency Management Agency shows urban search and rescue workers in action at the Alfred P. Murrah Building in Oklahoma City, April 1995. A computer graphic produced by the Geophysical Fluid Dynamics Laboratory, National Oceanic and Atmospheric Administration, depicts a simulation of Hurricane Emily off the North Carolina Coast, September 1993.