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12 THE BENEFITS OF MITIGATION: CASE STUDIES Though natural hazards may be inevitable, the disasters they precipitate can be prevented or mitigated. Reliable prediction and warning, care- fully planned emergency response, judicious land use policies, and hazard-resistant designs have all led to notable successes. The following case studies contrast situations in which actions were taken to anticipate a hazard with other situations in which no action was taken. They speak elo- quently of the promise of a hazard-resilient world. Bangladesh: Coping with Killer Cyclones In 1970, a killer cyclone struck Bangladesh and precipitated the worst storm disaster of this century, killing 300,000-500,000 people and leav- ing 1.3 million homeless. Many victims were migratory laborers, squatters, and fishermen sub- sisting on the shifting islets known as chars. They were caught without warning. In response to this event and the continuing dangers posed by such storms, the U.S. and Bangladesh governments worked closely to install a satellite-based severe storm warning system. Using a full array of new tools to track and forecast storm strength, direc- tion, and potential impact, this system allows residents of the low-lying coastal areas to be alerted to a storm's approach and to escape to higher ground. In the early morning hours of May 25, 1985, the warning system proved its worth as another killer cyclone of equivalent strength struck Bangladesh. Winds exceeded 160 kilometers per hour, generat- ing surf 3-8 meters above normal. The govern- ment had issued advance warnings- both nation- ally and locally- advising residents of the danger. Though some 10,000 died, the ultimate impact of the 1985 cyclone was many times less than that of the 1970 event. The ability to warn - to be understood in local dialects and to communicate accurately the probable threat to life and property with sufficient lead time for action - was the basis for this successful effort in the face of disaster. Tangshan and Valparaiso: Modern Earthquake Engineering In 1976, a magnitude 7.8 earthquake devastated Tangshan, China. Of the 1.5 million people living in the affected region, most lost their homes and more than 250,000 died. Nine years later, in 1985, a magnitude 7.8 earthquake occurred near Valparaiso, Chile, affecting some 1 million people. Though the quakes were of equal magnitude, only 150 died in Valparaiso and damage was moderate. The difference in the extent of damage in the two cities was due to building design. Valparaiso incorporated modern seismic design to prevent collapse and minimize damage and Tangshan did not. The limited residential, commercial, and industrial damage in Valparaiso contrasts sharply with the almost total damage suffered in Tang- shan and provides a measure of the potential of hazard-resistant design. Haicheng and Tangshan, China: The Lessons of Prediction Contrasting the Tangshan disaster with another Chinese earthquake shows the potential benefits of earthquake prediction. In February 1975, after studying various signs thought to indicate an impending earthquake, authorities in the north- ern province of Lianong ordered the evacuation of several cities. Some hours later, a large earthquake (magnitude 7.3) damaged 1,000 square kilo- meters (385 square miles) and demolished 90 percent of the city of Haicheng. Fortunately, the people were out in the streets and open spaces, and relatively few were killed or injured. A little over a year later, the Tangshan quake (magnitude 7.8) occurred. With earthquake pre- diction in its infancy, no short-term prediction had been made, and the poorly built masonry buildings became death traps. These experiences demonstrate the need to develop earthquake prediction from an unreliable art to an established science. In the United States, research on prediction is under way in Park field, on the San Andreas fault in California. Hundreds of instruments have been deployed there for continuous monitoring of minute physical changes in the earth. Though earthquake prediction depends on sci- entific research, use of this information depends on effective decision-making processes by scien- tists and local officials. They must decide when the public should be warned and how to ensure that the warning reaches all those who are vulnerable. Once warned, a public prepared by education and training mnst then take action, as in Haicheng.