Public Health Consequences of Earthquakes. Part II. Eric K. Noji, M.D., M.P.H. Centers for Disease Control and Prevention Washington, D.C.
PREVENTION AND CONTROL MEASURES Until earthquake prevention and control measures are adopted and mitigation actions implemented throughout the United States, a single severe earthquake could cause tens of thousands of deaths and serious injuries and economic losses exceeding one hundred billion dollars (5).
Primary Prevention of Earthquakes Although we can neither prevent earthquakes nor set off small ones to prevent big ones, we should take earthquakes into consideration before undertaking activities known to precipitate earthquakes, such as making deep well injections, filling water impoundments, and discharging nuclear explosives underground.
Safer Construction Recent research findings support the view that preventing structural collapse is the most effective approach to reducing earthquake-related fatalities and serious injuries (5). Engineering interventions have largely been directed to increasing the ability of new buildings to withstand ground shaking or to retrofitting existing hazardous buildings. The most stringent level of seismic security will allow buildings to withstand earthquakes with little or no damage (94).
Safer Construction (cont.) Anecdotal evidence from earthquakes in Guatemala (1976), Mexico City (1985), and Armenia (1988) suggests that suffocation from dust inhalation may be a significant factor in the deaths of many people who die without apparent severe external trauma (15,46,97). However, the use of certain building materials and finishes may reduce dust production--for example, plasterboard may produce less dust on collapse than wet applied plaster. Developing and using methods of reducing dust release during a building collapse could perhaps prevent many deaths.
Development and Enforcement of Seismic Safety Codes Because of improved building construction codes, land use planning, and preparedness, the losses in the San Francisco Bay area from the 1989 Loma Prieta earthquake and in the Los Angeles area from the 1994 Northridge earthquake were kept much lower than would have occurred in a less well-prepared region.
Many injuries and much of the cost and disruption from earthquakes are caused by the contents of buildings, including equipment, machinery, and other nonstructural elements. Therefore, the structural stability and robustness to violent shaking of all of these elements should be reviewed. A room-by-room review is likely to reveal many items that could cause injury to the room's occupants in the event of violent shaking. Although often beyond the purview of building codes (or any reasonable hope of enforcement for that matter), heavy furniture, glass cabinets, appliances, and objects placed where they could fall or be thrown about should be firmly secured to prevent them from striking people in the event of an earthquake. Special precautions must be taken with sources of flame or electric filaments in boilers, heaters, space heaters, pilot lights,cookers,etc.because violent shaking could cause fires. Nonstructural Measures
Drills for Evasive Actions During Earthquakes Earthquake drills are important. Earthquakes, although sudden, are usually not instantaneous. Building occupants usually have a few seconds to react before the shaking reaches maximum intensity, raising the possibility of taking evasive action to escape injury (50,87,102). Despite the relative lack of data on the efficacy of various evasive actions, it seems worthwhile for people to practice taking some evasive actions particularly since they will have just a few seconds to act when an earthquake strikes.
Drills for Evasive Actions During Earthquakes (cont.) However, anecdotal stories should not be the basis for responding to an earthquake: there is a distinct need to reassess all such widely accepted citizen safety actions to ensure that they are indeed the best responses (31,79,106). Only by conducting epidemiologic studies of the location of injured and noninjured people can we determine which behaviors are truly most likely to reduce the risk for injury.
Planning Scenarios for Earthquakes Relative chaos is likely to prevail immediately after a major earthquake. Area residents, cut off from the outside, will initially have to help themselves and their neighbors (16,17). They can best do this if they have already planned their responses to the most likely earthquake scenarios and practiced the necessary skills (107).
On the basis of the earthquake scenario that they develop, public health officials should devise a response plan. This plan should include the following:
Disaster Response to Earthquakes Disaster response to earthquakes is more akin to medical treatment than to prevention, but some aspects of the response may be likened to tertiary prevention in that those responding seek to limit further injury and to control the secondary effects of the earthquake (92). Prompt rescue should improve the outcome of victims, and early medical treatment should lessen the sequelae of the primary injuries (e.g., wound complications, chronic neurological disabilities). Provision of adequate food, water, and shelter should especially help people in vulnerable age groups and those with pre-existing diseases. Effective environmental control measures should prevent secondary environmental health problems. Identification and control of long-term hazards (e.g., asbestos in rubble) should reduce chronic health effects.
Search and Rescue People trapped in the rubble will die if they are not rescued and given medical treatment. To maximize trapped victims' chances of survival, search-and-rescue teams must respond rapidly after a building collapses.
Search and Rescue (cont.) With the exception of personnel from countries in close geographical proximity, foreign assistance usually arrives after the local community has already engaged in much of the rescue activity.
Surveillance of Search and Rescue Activities The conduct of future rescue operations can be enhanced by lessons learned from the position and circumstances of trapped victims and from specific details about the extrication process itself. Knowledge of collapse conditions helps set rescue priorities.
Medical Treatment Just as speed is required for effective search and extrication, it is also essential for effective emergency medical services: the greatest demand occurs within the first 24 hours (33). Ideally, "disaster medicine" (medical care for victims of disaster) would include immediate life-supporting first aid (LSFA), advanced trauma life support (ATLS), resuscitative surgery, field analgesia and anesthesia, resuscitative engineering (search and rescue technology), and intensive care (26).
Medical Treatment (cont.) The medical and public health impact of a severe earthquake may well be compounded by significant damage to medical facilities, hospitals, clinics and supply stores within the affected area (117). In the worst-case scenario, a hospital building may itself be damaged by the earthquake, and the hospital staff may have to continue emergency treatment without using the buildings (118).
Surveillance of Injuries at Medical Treatment Sites Treatment sites, whether at hospitals or in temporary field clinics should designate someone to organize surveillance of injuries, collect data, and see that the data are tabulated and reported to disaster-response health officials.
Dissemination of Public Health Information Public health organizations should work out scenarios for various information-dissemination contingencies before an earthquake occurs. This will be difficult. Telephone service is likely to be disrupted in the impact area of an earthquake. However, police, fire, and many emergency service organizations maintain radio networks, which public health officials may be able to use. Furthermore, radio and television news crews often arrive at the scene of a disaster with sophisticated communications equipment.
Environmental Health In the day or so immediately following an earthquake, the priorities are undoubtedly rescuing and treating victims. Saving the lives of those injured or trapped far outweighs most other needs. However, the other needs of a population suddenly deprived of homes, possessions, urban services, and other essentials cannot be ignored and will assume greater significance as soon as the life-threatening situation stabilizes. If large areas of buildings are destroyed, the population made homeless will have an urgent need for shelter and food (121). They will also need drinking water, clothing, sanitation, hygiene education, and basic comfort provision. Effective environmental control measures should prevent secondary environmental health problems.
Detailed Follow-Up Epidemiology Few earthquakes have been adequately studied epidemiologically, with the exceptions previously noted (122). It is vital that plans for follow-up epidemiology be developed before an earthquake occurs so that the initial surveillance data collected will allow proper follow-up (123).
CRITICAL KNOWLEDGE GAPS Because we do not know enough about the precise causes of deaths and nature of injuries that occur during earthquakes, relief services are often misdirected and community medical/health planning for earthquakes is often inadequate (126). The more we know about the manner in which injuries and deaths occur, the better we can prepare for and respond to earthquakes. The following are steps researchers can take to help health officials and individuals better prepare for earthquakes.
CRITICAL KNOWLEDGE GAPS (cont.) • ! Evaluate the role of occupant behavior in earthquake injury susceptibility. • ! Collect more extensive data concerning the circumstances of entrapment (e.g., location of victims in the collapsed structure). Lack of such data has made planning search and rescue actions, providing proper medical care, and requesting the appropriate outside aid more difficult.
CRITICAL KNOWLEDGE GAPS (cont.) • ! Incorporate postearthquake research findings into specific emergency-preparedness and response-guidance protocols. The gap between what researchers have learned and the knowledge base underlying the protocols of the "user community" (e.g., response and recovery organizations) can be lessened considerably if researchers and members of the user community interface more effectively. Results of research should be communicated to key decision-makers and citizens at national, state, and local levels so that they can incorporate such findings into community earthquake-preparedness and earthquake-response programs.
METHODOLOGIC PROBLEMS The data needed for comparative earthquake studies is often lacking, including such basic information as the magnitude or intensity of the earthquake, the number of deaths, the number of people injured (using standard definitions) and the size of the affected population (131). The study of earthquake injuries is difficult to approach from any narrow background, as it requires the active collaboration of workers having a number of areas of expertise (122). First, one must understand the mechanisms of physical failure in earthquakes. This requires structural engineering and architectural competence.
METHODOLOGIC PROBLEMS (cont.) The difficulty of collecting information on entrapped people is compounded by the fact that traditional, institutionalized sources of injury data (e.g., hospital medical records) do not usually document information such as where in a building the injury occurred, which attributes of the building contributed to the injury, the injured person's initial behavior when ground shaking began, and the circumstances of entrapment. Unfortunately, this lack of data on the circumstances of entrapment tends to hinder the development of effective search-and-rescue techniques and effective injury-prevention strategies.
METHODOLOGIC PROBLEMS (cont.) Analytic studies that establish and quantify the magnitude of the relationship between significant risk factors and injuries are also very difficult to organize and conduct in an earthquake-devastated region where most dwellings have been destroyed and populations relocated--factors that make locating injured people extremely difficult. Furthermore, in most areas of the world where major earthquakes have occurred, official census records are poor.
RESEARCH RECOMMENDATIONS • ! Seek to understand the mechanism by which people are killed or injured in earthquakes (e.g., what components of the building have directly caused trauma). Such knowledge is essential to developing effective prevention strategies (134).
RESEARCH RECOMMENDATIONS (cont.) • ! Establish detailed autopsy data on a sample of earthquake victims to determine the exact cause of death. Such information could provide the basis upon which to suggest modifications to buildings to prevent death. Similar autopsy information has been valuable in analyzing automobile crashes and making appropriate modifications to automobile interiors.
RESEARCH RECOMMENDATIONS (cont.) • ! Analyze previous building failures in the context of injury studies. The results could lead to the development of simple but effective retrofit prevention strategies designed to mitigate injury or death.
RESEARCH RECOMMENDATIONS (cont.) • ! Examine the manner in which buildings collapse during other kinds of disasters. For example, structural collapses caused by tornadoes, hurricanes, single-building construction failures, mine disasters, terrorist bombings, aircraft or train crashes, wartime experiences, and so on could provide valuable insights into the manner in which buildings collapse during earthquakes.
SUMMARY A major earthquake in one of our urban areas ranks as the largest potential natural disaster for the United States. Most of what can be done to mitigate injuries must be done before an earthquake occurs. Researchers have identified a number of potentially important risk factors for injuries associated (either directly or indirectly) with earthquakes. Because structural collapse is the single greatest risk factor, priority should be given to seismic safety in land-use planning and in the design and construction of safer buildings.