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24 One of the most destructive tomadoes in Wyoming history struck Cheyenl1e, the state capitol, on July 16, 1979. As sem here from about 420 meters (1,300 feet), the twister contains a whirling mass of debris-from dust to 2 x 4s- with very little moisture. Before its rampage ended, hlll1dreds of homes lay in ruins, with damage estimated at $32 milliol1. Casualties were kept to a minimum with the help of civil defense sirens and warnings broadcast by the media and spread by alert neighbors. \1 are building codes and regulations. They too offer ~ both benefits and problems for transferring expe- ffi rience from one community or country to another. ~ ::' The benefit is that a group of knowledgeable individuals has assessed experience and research results to develop the code. The problem is that a code responds to the conditions, building mate- rials, and construction practices of the community that originated it; the code may not be entirely applicable outside this context. Nonetheless, builders in other nations, unaware of these limita- tions, may try to use the code without adapting it. As mentioned earlier, a key limitation to miti- gating damage from natural hazards is the large inventory of substandard, even hazardous struc- tures. Most worldwide research and development of building practices focuses on new buildings, not on rehabilitating existing unsafe buildings. Because existing facilities represent the main hazard everywhere in the world, research and performance evaluations have much to offer this critical area. HAZARD PREDICTION Predicting a major natural hazard has enormous potential for reducing its disastrous con- sequences. Even short advance notice gives time to protect life and property; a long period provides an opportunity to relocate and reinforce property. The capability to predict varies with the type of hazard and has made considerable strides through research and technical understanding. Computer modeling of watersheds, when linked to a network of meteorological and hydrographic stations, has enabled accurate flood warnings to be developed. From tornado watch programs linked to weather radar systems, the path of a tornado can be estimated, giving both the community and its fire, rescue, and medical services a short time to prepare. The development of Doppler radar has greatly advanced the ability to predict weather- related hazards and has lengthened the time between warning and the onset of a hazard. In regions of tropical storms, the precision of warn- ings issued in advance improves as a storm approaches, hour by hour; ultimately, accuracy is dictated by mathematical models of a storm and the data feeding into them, The Pacific Tsunami Warning Center and its network of member conntries is an excellent