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7 Indirect Losses Indirect losses follow from the direct effects of an earthquake. They may be very unportant, but are difficult to evaluate. FI1tE Most loss estimates in the United States have not included losses from fire in a formal, quantitative way. While fire has not been a major factor in recent earthquakes in the United States, more than 100 ignitions occurred in the 1971 Son Fernando earthquake, and a shopping center fire was the single largest loss in the 1984 Morgan HiD, California earthquake (M 6.2~. Thus, the specter of fire loss following earthquakes, similar to the 1906 San Francisco earthquake, is always present. Scawthorn et al. (1981) and Oppenheim (1984) have made starts toward a forma] procedure for evaluating expected losses from fires. The discussions of this topic in ATC-13 and Steinbrugge and Lagorio (1982) are also useful. More recently, Scawthorn (1987) has provided estimates of losses due to fire following earthquakes in the Los Angeles and San Francisco regions. Data for the initiation of fires following earthquakes in the United States, and especially for the different conditions in Japan, exist. Models can include consideration of time lags in reporting fires and responding to them as well as weather conditions to estimate the possible spread of fire. 61
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62 However, such models should be used with caution in a gener- alized loss study because major work remains to advance the state of the art. Inherently, the problem is very complex. A recent re- minder that the state of the art of forecasting earthquake-caused fires is poorly developed is provided by the work of Hansen et al. (in progress) on the 1906 San Francisco earthquake. A much larger number of ignitions has been documented than was previously re- ported, and other previous data, concerning casualties especially, are also being significantly revised. Possible losses from fire, and the implications to disaster re- sponse planning, certainly must be recognized. Property losses from fire are of great concern to the insurance industry, and attempts to quantify possible fire-related losses will certainly continue. From the emergency planning standpoint, information concerning the expected performance of the water supply, communication, gas distribution, and highway and street systems can be used as a basis for devis- ing emergency response plans. Postearthquake fire modeling is also useful to identify general areas of high conflagration potential (e.g., concentrations of wooden buildings) or special risk factors unique to the postearthquake situation (e.g., telephone, transportation, or water system outages). RELEASE OF IIAZARDOUS MATERIALS Concern about potential releases of hazardous materials was em- phasized in the user workshop. I.aws in many states and communities have required that an inventory of hazardous substances be main- tained at the local level, and Title ITI of the Superfund Amendments and Reauthorization Act of 1986 imposed nationwide inventory re- quirements. Lacking legal sanction for having such an inventory, it may be impossible to secure the cooperation of industrial facilities in preparing one. In general, there is only a limited amount of data from earth- quakes upon which to judge the likelihood that releases will occur, as a function of ground-shaking intensity. The manner in which substances are contained will be the major factors affecting the prom ability of releases. For some general types of components, such as tanks, considerable earthquake performance data and analytical or test findings are already available. Even here, however, this is little direct information as to the likelihood of a release given that a tank has overturned. Development of methods for evaluating the seismic
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63 resistance of a range of storage arrangements is an important task for the future. ECONOMIC IMPACTS Many economic impacts are associated with earthquake damage. These include loss of production capacity in individual manufacturing facilities, lom of income to commercial enterprises where functionality is destroyed or Trip aired, the loss of jobs, economic impacts on other undamaged businesses within a region, and losses to industry and commerce located outside the affected region but linked economically to it. In some instances, economic benefits may be associated with an earthquake, such as an influx of federal aid and the creation of new types of jobs. The need to undertake such an analysis was a major motivation for FEMA's sponsorship of the ATC-13 effort. If such losses are to be considered, the inventory must mclude considerable information. The economic function of buildings must be identified, and commercial and industrial activities categorized. The 35 basic social function categories in the ATC-13 report are reasonable. However, given the inadvisability of assigning buildings to construction classes based only on socioeconomic data, the pane] estunates that about 25 to 50 percent more effort would be needed to include this level of classification of uses in an inventory. In addition, considerable effort by economists wall also be needed to develop the economic models that link various commercial and industrial activities inside and outside the region. The pane! recognizes the potential value of analyses of this type, and encourages them. It recommends that a pilot study of this type be added to a future loss estimation study.