Hazards Risk Assessment Methodology for Emergency Managers: A ...

Natural Hazards 28: 271–290, 2003. © 2003 Kluwer Academic Publishers. Printed in the Netherlands.

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Hazards Risk Assessment Methodology for Emergency Managers: A Standardized Framework for Application NORMAN FERRIER1 and C. EMDAD HAQUE2 1 Toronto Emergency Medical Services, Toronto, Canada, E-mail: [email protected]; 2 Natural Resources Institute, University of Manitoba, Winnipeg, Manitoba, Canada R3T 2N2,

E-mail: [email protected] (Received: 29 June 2001; accepted in final form: 10 April 2002) Abstract. The public and the decision and policy makers who serve them too often have a view of community risks that is influenced and distorted significantly by media exposure and common misconceptions. The regulators and managers, responsible for planning and coordination of a community’s mitigation, preparedness, response and recovery efforts, are originated from a variety of disciplines and levels of education. Not only must these individuals deal with the misconceptions of their communities, but also frequently lack a basic methodology for the assessment of risks. The effective planning of mitigation and response are, however, directly dependent upon the understanding of the complexities, types, and nature of risks faced by the community, determining the susceptible areas, and conceptualizing human vulnerability. In this study, a review of the existing literature on both the conceptual underpinnings of risk and its assessment is attempted. A standardized framework is proposed for use by all emergency managers, regardless of training or education. This framework consists of the numerical ranking of the frequency of the event in the community, multiplied by a numerical ranking of the severity or magnitude of an event in a given community, based upon the potential impact characteristics of a ‘worst-case’ scenario. This figure is then multiplied by a numerical ranking indicating the Social Consequence; a combination of community perception of risk level and collective will to address the problem. The resulting score, which is not strictly scientific, would permit emergency managers from a variety of backgrounds to compare levels of community exposure to such disparate events as hazardous materials spills and tornadoes, and to set priorities for both mitigation efforts and for the acquisition of response needs, within the availability of community resources. Key words: risk assessment, emergency management, natural disasters, technological disasters, community vulnerability, mitigation, resilience.

1. Introduction The conventional wisdom in emergency management advocates the use of an “all-hazards” approach to planning for a community’s response to emergencies. An earlier version of this paper was presented at the Mitigation 2000 Conference, organized

and sponsored by the Canadian Emergency Preparedness Association, Manitoba Chapter, Winnipeg, Canada, November 16–19, 2000.

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Unfortunately, both the public and the elected officials who serve them too often have a view of community risks that is distorted by media exposure and common misconceptions. The effective planning of mitigation and response are, however, directly dependent upon the understanding of the various types of risks faced by the community, determining the susceptible areas, and conceptualizing human vulnerability. A great deal of work has already been accomplished with respect to the measurement of the effects of various types of emergencies, usually expressed in terms of the energy or force generated. However, there is often no direct relationship between the force generated by an event and the community impact. In addition, the problem of how to evaluate the relative risks from various types of different phenomena remains. This study begins by addressing some definitional and conceptual ambiguities. It examines the nature of risk and its components, as well as the identification of hazards faced by the community in real-life. The importance of assessment of vulnerability is also critically reviewed. While the local level data and scientific methods for risk assessment are scanty, this research proposes the use of a standardized methodology to permit emergency managers and others to evaluate various types of dissimilar risks, as well as the potential for impact by those risks on the community. Finally, the advantages and disadvantages of such a system are explored.

2. Risk, Hazard and Uncertainty: Some Conceptual Considerations Clarification of some significant definitional aspects of risk analysis prior to any discussion on risk assessment and pertinent methodologies is important. Though the term risk is often treated as synonymous with hazard, risk has “the additional implication of the chance of a particular hazard actually occurring” (Smith 1996, p. 5). A distinction can be made that hazard is a potential threat to humans and their welfare whereas risk is the probability of hazard occurrence. Okrent (1980) succinctly explained this distinction through some examples. Consider that two individuals are crossing an ocean, one in a liner and the other in a rowing boat, and one can readily find the difference. The main hazard (deep water and large waves) is the same in both cases but the risk (probability of drowning) is very much greater for the person in the rowing boat. Thus, while an earthquake hazard can exist over an ocean floor, risk to people and property can occur only in an area where people, houses and possessions exist. In our every day life, we all face some degree of personal as well as collective risk. Besides facing risk in the environment, every day individuals and institutions make decisions to take some risks and avoid others. For instance, when we decide upon the location of our residence, we may choose from various options. Despite its risk to flooding, a river-side lot is always attractive. If permitted by affordability, many of us would decide to take up such an option. Also, because of their aesthetic value, and better privacy, many people decide to live in houses in heavily

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treed areas or close to forests, although it is well-known that there is a risk from potential forest fire. Here, the extent to which risks are voluntary and involuntary is particularly significant. The degree of individual human responsibility for risk avoidance or minimization increases greatly from the essentially unavoidable or accidental extreme natural or technological events to largely self-induced social hazards such as smoking or mountaineering. In order to measure and evaluate risk, one must first define its characteristics and parameters. Like many other terms in emergency management, there are a variety of definitions for the term risk, and everyone seems to have their own individual notion of precisely what this term means. For the purpose of this discussion, risk is defined as the product of the vulnerability of either the entire community, or of subgroups within that community, to the effects from a given event, and the potential for the occurrence of that event. Risk hence refers to the possibility or chance of encountering danger, suffering, loss, and injury. When one says something is at risk, the speaker surely implies that it is being threatened by uncertainties. The concept of risk and the notion of uncertainty are closely correlated. The Chinese word for risk is “weij-ji”; it combines the characters meaning “opportunity/chance” and “danger” to imply that uncertainty always involve some balance between gain and loss. One may calculate that the probability of one’s house on the Prairies to be hit by a tornado is 0.005%, meaning that approximately five households, out of a thousand, on average will experience tornado strike. Once a house has experienced a tornado disaster, one can no longer find relevance of risk from that particular tornado, for the fact that it is a certainty. If the house is rebuilt, only then one would find relevance of further risk of a tornado strike. But if the house is totally demolished and not rebuilt, the risk of the house being hit by another tornado drops to zero. Estimates of risks, thus, insofar as they are expressions of uncertainty, will change as knowledge and information gathering. Different uncertainties appear in risk estimation in different ways. There is clearly a risk that an individual could be adversely affected by a flood if that person knowingly or unknowingly live in a floodplain. One part of this risk is stochastic; it depends on whether there is an abnormally high precipitation in that year and whether such precipitation resulted in over-saturation in soil. Another part of the risk might be systematic; it will depend on the nature of the elevation and other pertinent features of the house. Also, some estimates of uncertainties are subjective, with differences of opinion arising because there is a disagreement among those assessing the risks. Suppose one wishes to assess the risk of inhabitants to climate change-related hazards. Without any further information, analysts would say about any measure of risk is that it lies somewhere between zero and unity. Extreme opinions might be voiced; one assessor might say that we should initially assume a risk of unity, because we do not know whether unusually rapid climate change is a fact. Another assessor might take the opposite extreme, and argue that we should initially assume that there is zero risk, because nothing has been proven alarming. Here and elsewhere,

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we like to argue that it is the task of the assessor to use whatever information is available to obtain a probability number between zero and one for a risk estimate, with as much precision as possible, together with an estimate of the imprecision. Environmental hazard is the threat potential posed to human or nature by events originating or transmitted by the natural or built environment. Risk Assessment, formally, is an appraisal of both the types and degrees of threat posed by an environmental hazard. Risk assessment cannot be separated from value judgements and choices which are primarily conditioned by individual beliefs and circumstances. Many people and institutions make decisions and take actions regarding hazards based on their personal or collective perception of risk rather than on some objectively derived measure of threat. Risk perception, for this reason, has to be considered as a required component of risk management alongside more scientific assessments. Perceived risks are often distinct from objective risks, largely because people perceive some risks very differently from the predictions made by the more objective assessment models. Perceived risk is based on individual’s personal perception of the threat, and associated with his/her value judgement. Usually such cognitive process is based upon emotional reaction rather than a “reasoned response”. Contrary to this, assuming that adequate information and knowledge is available, objective risk is based upon scientific data, assessments, and other tools and methods – it is not significantly conditioned by individual’s beliefs or circumstances. Resolving the resulting conflict between the results of technical risk analysis, by which risk is determined, and more subjective risk perception is a major factor in most hazard management strategies. During the 1997 flood in the Red River Basin of Canada, the municipalities located along the Red River in Manitoba were informed by the Manitoba Emergency Measures Organization (MEMO) about the impending flood hazard. MEMO relied on the data procured from Minnesota and North Dakota, U.S.A., that were scientifically analysed for flood forecasting and the observation from model experiments, asked for appropriate preparedness. The municipal administrators and executives have had difficult time to convince municipal councilors as well as other residents to take preparatory actions. This happened because of the fact that the underestimation of low frequency events and hazards is common which results in noticeable distortion in the perceive risks relative to the objective risks. There are also other factors that result in lack of planning initiatives; these include denial, apathy and the like.

3. Risk Assessment Methodology Literature on risk assessment methodology is limited, although some work has attempted to address this area quite comprehensively. The seminal work by Kates and Kasperson (1983) which was substantiated later by Smith (1996), Wilson and Crouch (1987), and O’Brien (2000) are worth reviewing. Risk assessment


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consists of three components: (i) hazard identification, (ii) estimation of risk and vulnerability, and (iii) social consequence evaluation.

3.1. HAZARD IDENTIFICATION An identification of hazards likely to result in disasters, i.e., what hazardous events may occur? What constitutes a threat? Thus, environmental hazard identification searches the patterns in the interface between the natural environment and human society, involving threatening events and consequences. For most of human history, the identification of environmental risks arose from direct human experience of events and consequences or from the application of rituals. In modern days, however, we rely on science and technology which are obtained by observation and testing of ideas and facts. The major tools of environmental hazard identification will continue to be: research, screening, monitoring, and diagnosis. In screening hazards, a standard procedure is applied to classify products, processes or phenomena for their hazards potential whereas in monitoring, products, processes, or phenomena are recurrently observed, recorded or analysed for hazardous events or impacts. Diagnosis is more comprehensive in the sense that it is an overall assessment of screened and monitored data for recognizable environmental symptoms or consequences. The process of diagnosis begins with observation of the abnormal and concludes with some form of hazard identification. When establishing the frequency of occurrence for a given event, or hazard identification, there are a number of issues which must be explored. The exploration is not unlike that undertaken by a journalist when researching a news story. When did the event last occur? If the event has occurred, have mitigation measures been taken to prevent or minimize recurrence? If the event has not occurred in this community before, why is this the case? Are there local characteristics, such as topography or climate, which prevent the occurrence of a given event? It is likely that in any given local area some types of disasters (e.g. tsunamis in inland areas) may be relatively dismissed from the identification process. The answers to these questions will permit one to sort through the immense list of natural disasters, and to focus upon those with any real potential for occurrence in a particular area. If the event has occurred in the past, how frequently? What is the annual probability of occurrence, based upon past experiences? To illustrate this, let us consider the incidence of severe ex-tropical storms (hurricanes) in the City of Toronto, Canada. Toronto has typically experienced two such events per century, the last event being Hurricane Hazel, which occurred in 1954. Is Toronto at risk from a hurricane? If an event only occurs in an area about twice per century, but the last time was forty-six years ago, it is increasingly probable that this event will recur in the near future. While this method of calculating probability is not highly precise, it is useful in providing a general guide to the probability of a given event. Why did the event occur? What circumstances, if any, contributed to the occurrence of the event? Do these circumstances still exist or do they recur periodically?

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Where specifically in the community did the event occur? Has the area changed in a manner that would prevent recurrence or worsen effects if the event were to recur? If the area in question is known to be prone to flooding, for example, how much residential, commercial or industrial construction has historically occurred on the flood plain? What construction remains on the flood plains, and have measures been implemented to eliminate future construction in these vulnerable areas? This detailed questioning process represents the “When” “Where” and “Why” of the journalistic analogy, and answering them completely will provide a manager with a credible description of past occurrences, as well as with a realistic understanding of the potential for future occurrence. The answers to the above questions can be found in a variety of sources. (a) Scientists and researchers with a specific interest in the phenomenon under consideration are good resource personnel. Consultation with these individuals can greatly reduce the research time required of the emergency manager, and will usually also provide the best estimates of probability. However, it should be considered that there are many differences in the scientific community as to what various data means, also there are many cases where the data is simply not available. For example, in many smaller communities, soil studies have not been conducted and there is little data to assist in the probability of landslides. (b) Published materials such as textbooks, journal articles and databases are another valuable source. Material published on the internet is also potentially helpful, once its accuracy has been validated. In Canada, accurate historical information on Canadian disasters is available by means of a Disaster Database and Browser, available free of charge on the Office of the Critical Infrastructure Protection and Emergency Preparedness, Canada website. This database is part of a larger project housed at the Centre for Research into the Epidemiology of Disasters, located at the Catholic University of Louvain, in Belgium. (c) Historical records available in local library or municipal records are particularly useful in providing old maps as well as photographs of the event, either of which may increase managers’ understanding of the circumstances surrounding occurrence. (d) While newspaper reporting may tend to be somewhat superficial at times, it can be valuable for pinpointing uncertain dates of occurrence. This permits the researcher to find more detailed records, and will often link earlier occurrences, for the purpose of comparison. (e) Long-time residents are an oftenoverlooked resource. While not highly precise, this group is often useful in pointing the managers in the right direction for the balance of their research. Having personally experienced the event in question in the past, residents can be particularly useful in identifying hazards in their communities. In addition to emergency managers’ queries concerning “who”, “what”, “how” and “how much”, it also may include intuition of the locals, in which the local community members may be able to predict when another event may occur, primarily based on past experience. Examples could be cited from the North American farming communities or the First Nations communities of the North.


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3.2. ESTIMATION OF RISK AND VULNERABILITY TO HAZARDOUS EVENTS An estimation of the risk to hazardous events, require to know what is the probability of each event as well what is the nature of the consequences? Estimation of such human (lives and resources) vulnerability thus seeks to measure the likelihood of an event (of some magnitude) occurring, and the likelihood and nature of the impacts that follow. However, there are some fundamental limitations in risk estimation methodologies that are based upon human experience. Humankind as a collective entity is at risk from threats greater than or different than its individuals or separate groups’ experience. No matter what ingenuity is expanded, these limits would put us in what Kates (1962) called the “prison of experience”. In some cases, human perception is greater than objective reality (discounting the state of human cognition and perception); in other cases, the perceived experience of hazard is lesser than the reality. In addition, human records are biased to the recent and identified phenomena. Also, human memory is biased to the recent and most impressionable events. As well, our cognition is inclined towards the ordered and determinate phenomena, and attempts to avoid unorganised phenomena. Because of these cognitive constraints, objective reality may not be reflected most of the time in our efforts to share our perceived experience. In order to overcome some of these limitations and to provide effective, measurable and comparable tools, extrapolations of events, in probabilistic terms, are traditionally made based on historical data. To put risk in this perspective, first, the probability of recurrence of particular geophysical, biological and other natural events is assessed through historical trends; for example, from lengthy historical records it is possible to determine the approximate size of a 100-year flood and to estimate the probability of certain-sized events occurring in any given year. Second, to reflect upon how a particular event will adversely impact upon human welfare, human vulnerability to loss is incorporated into the equation. Although there are variations in the usage of the term vulnerability in the literature, a common denominator in it is the conditions of people and their livelihood (Cannon, 1994; Blaikie et al., 1994). “Vulnerability is a characteristic of individuals and groups of people who inhabit a given natural, social and economic space, within which they are differentiated according to their varying position in society into more of less vulnerable individuals or groups” (Cannon, 1994, p. 19). It is a complex characteristic produced by a combination of factor derived primarily from socioeconomic factors that result in hazards having a different degree of impact. Thus, this concept involves the capacity of individual or groups to anticipate, cope with, resist, and recover from the impact of hazards. Most natural events are characterized by a wide range of variation through time in the use of energy and materials for environmental processes. The outer limits of this range are known as ‘extreme’ and magnitude-frequency relationships are used to depict such extremes (Smith, 1996). But extreme natural events are not considered disasters unless they cause large scale deaths or damages. As Hewitt

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Table I. Basic elements of quantitative vulnerability estimation Event

Probability

Vulnerability to lose (arranged in increasing order)

Cumulative probability

E1 Ej En

P1 pj pn

V1 Vj Vn

P1 = p1 + · · · + pn = 1 Pj = pj + · · · + pn Pn = pn

and Burton (1971) explained, most socioeconomic conditions are adjusted to some expectation of the ‘average’ characteristic. When the variation in the environmental element remains fairly close to this expected range, the element would not be hazardous, whereas when the variability surpasses some ‘threshold’ beyond ‘normal’ band of tolerance, the same variable begins to induce damage and create people and resources vulnerable. Risk (R) is therefore estimated as some product of probability of occurrence (p) and vulnerability to loss (V ): (R = pXV ). If every event resulted in the same consequences, it would be necessary only to calculate the frequency of occurrences. But most environmental hazards, such severe storms, or floods have highly variable impacts and some assessment of these consequences, and their likelihood, is also required. Based on Krewski et al.’s (1982) work, it is possible to develop a detailed procedural illustration of vulnerability estimation. From experience, it is known that n different mutually exclusive extreme events E1 . . . En may take place. From historical and recent data from various sources, one can determine that Ej will occur with probability pj and result in a vulnerability to lose equivalent to Vj , where j represents any of the individual numbers 1 . . . n and V1 . . . vn are measured in the same units, e.g., dollar or lives lost. It is assumed that all the possible events can be identified in advance. It thus arises that, p1 + p2 . . . Pn = 1. After arranging the n events in order of increasing vulnerability to lose (V1 < · · · , Vn ), the cumulative probability for an individual event can be calculated as Pj = pj + · · · pn . This specifies the probability of the occurrences of an event for which the loss is as great as, or greater than Vj , as shown in Table I. If one can categorize all possible events in terms of the vulnerability of property loss (expressed in dollars), it may be possible to produce a vulnerability assessment in the following manner:


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Table II. A hypothetical vulnerability estimation by the value of property loss Property loss $

Probability (p)

Cumulative probability (P ) of exceeding

0 100,000 500,000 1,000,000

0.950 0.030 0.015 0.005

1.000 0.050 0.020 0.005

Table III. A hypothetical vulnerability estimation by human casualties Number of deaths

Probability (p)

Cumulative probability (P )

0 10 20 30

0.990 0.006 0.003 0.001

1.000 0.010 0.004 0.001

This theoretical example shows that there is a 95 percent chance of no property loss and only a 2 percent chance of a property loss of $500,000 or greater. In some circumstances, it may be necessary or desirable to produce a summary measure of risk. This can be done by calculating the total probable loss: R = p1 V1 · · · + pn Vn . In this example, R would be $15,550. Alternatively, the maximum loss could be calculated. Such a measure ignores the probability of occurrence and takes the risk to be equal to the maximum loss which, in this case, would be $1,000,000. The same methodology can be applied when damaging events cause loss of life. For our stated example, an appropriate tabulation might be: Despite the apparent precise nature of quantitative vulnerability estimation, uncertainty surrounds the use of such methodology for environmental hazards. In the earth sciences, for example, the practice is to make the majority of risk estimates solely on the basis of the probability of an event, rather than on the probability of the event causing a particular loss of life or amount of economic damage. Loss-vulnerability is basically the cost of an event, considered in both human and financial terms, and in the loss of critical infrastructure. Relative levels of vulnerability are considered for both individuals, subgroups within the community, or for the community as a whole. While the community must respond to the effects of a disaster, those effects are often localized, or even individual. Planning for individuals might be a daunting task, however, the consideration of the relative

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Figure 1. Groups at particular risk.

vulnerabilities and resiliency of particular sub-groups within the community (see Figure 1) can be useful in identifying the potential vulnerability and resiliency of the community as a whole (Buckle et al., 2000). The identification of vulnerabilities is central to the processes of mitigation, preparedness and response, which in turn directly affect community resiliency. A community’s level of relative resiliency is inversely proportionate to the level of vulnerability. When establishing the potential effects of a given event on a community, or vulnerability assessment, the emergency manager is once again required to conduct research that is not unlike journalism. As noted above, the questions in this step involve “who”, “how” and “how much”. What is the probable impact in a ‘worst case’ scenario? What is the cost in human terms (e.g., injury, loss of life, loss of the necessities of life), in economic terms (e.g., cost of response, interruption of business) and in environmental terms (e.g., loss of ecosystems)? Would some sub-groups be more or less affected than others by the incident? It is well established that some elements of the community are, under normal circumstances, generally more vulnerable than others (Buckle et al., 2000). Indeed, there is an increasing belief that “proximity to an extreme nature event combines with low economic or social status to result in deadly consequences” (Goodyear, 2000). In Dennis Mileti’s (1999) words, “there are many details to flesh out to complete the understanding of the various ways in which different people or groups prepare and respond to disasters. In addition, there is much to learn from research done in other countries, and from cross-cultural work”.

3.3. SOCIAL CONSEQUENCE EVALUATION Does the community have the resources to cope with this level of impact? If not, where would those resources have to come from? How would they have to be delivered, and over what period? In some cases, such as the September, 1999 Taiwan earthquake (Smith, 1999), or in the cases of similar recent disasters in Colom-


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bia and India, resources may be required from a variety of international sources. What is the composition of the affected community? Varying community composition may profoundly affect the needs of the community during the response and recovery phases (Ferrier, 1999; Haque, 2000a). The impact of an event upon a community can be changed by the presence of concentrations of particular age or socio-economic groups, or by the presence of one or more large ethnic groups (Victor-Guild, 1999). What are the secondary costs, in both human and economic terms? Would critical infrastructure (e.g., roads, bridges, and water supply) be seriously damaged or destroyed? Does the community have the resources to reestablish or repair these infrastructure elements, and, if not, from where would these resources have to come? How long would it take to restore the normal standards of living within the affected community? An evaluation of the social consequences of the derived risks, i.e., what is social evaluation of the loss created by each event, is the final component of risk assessment? As Tobin and Montz (1997) have demonstrated, risk should be viewed as existing on a two-dimensional plane for any specific location, the extremes of which are high probability – low impact and low probability – high impact risks. An example of the former might be a snow blizzard in Manitoba, Canada; a level 5 hurricane striking Ontario, Canada, would illustrate the latter. In its simplest form, as explained above, risk can be defined as the product of probability of occurrence and loss- vulnerability of an event. Such “technical risk” computation although provides a scope for making comparisons by combining the two fundamental elements of risk in a logical and quantitative form, it is not adequate to reflect society’s views and perceptions of risk. Ann Whyte (1982) in this context argued that because these aspects greatly influence attitudes, actions, and ultimately vulnerability, social values must be accounted for in risk estimation. She offers a method to alter the risk formula from “risk equals to probability of occurrence times magnitude of loss” to the following: (R = pxV n ), where R = risk, p = probability of occurrence, V = vulnerability to loss, and n = social values. Whyte’s modification allows for inclusion of social concepts of risk, and as a result, recognizes variation in perception in different contexts (Whyte and Burton, 1980). The difficulty, of course, lies in trying to put a value on n (Zeckhauser and Shepard, 1984; Haque, 2000b). As the loss-vulnerability is not only a function of population, settlement, property, and infrastructure, it is also a function of mitigation and preventive measures adopted prior to the event. It has been argued that when n is sufficiently high, mitigation measures are sought in an attempt to lower the ultimate value of n. A modification of the previous definition is therefore necessary. In order to simplify the application of n in the equation, we suggest that multiplication of social rankings should be made; these aspects will be discussed in the next section of the paper. People usually compare risks with other risks, but

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Figure 2. Frequency Evaluation Scheme.

also often people compare risks and benefits (Haque, 2000a, b). In between these two evaluations lies the comparison of risks and the actions or costs of preventing potential disasters known as cost-effectiveness studies. The method raises the question: is it really worth to allocate certain resources for preventing or minimizing a probable event? It basically focuses on preventive or mitigation cost, but does not stress on direct benefits from such resource allocation. In precise, the methods of Social Consequence Evaluation must incorporate a comparative perspective. 4. Conducting Risk Assessment and its Application 4.1. A RISK ASSESSMENT SCHEME FOR APPLICATION In the proposed operational method, risk is expressed as a product of frequency times vulnerability times social evaluation. In “hazard identification”, which is the first step, the emergency manager is required to compute or find the probability of occurrence of an extreme event that surpasses the ‘threshold’ of the community. At the local level, often availability of, and access to, scientific statistics depicting probabilities of events are either non-existent or very limited. Under such circumstances, it is important to generate “hazard identification” data at the community level. The emergency manager is required to list every conceivable hazard. This list is based upon the emergency manager’s own knowledge, and on simply asking others which events they feel are likely to occur. This list is then reviewed, and those events that are made impossible by local topography or climate (e.g., avalanche on a tropical island) are discarded. What remains is a list of events that have some reasonable potential for occurrence, and which require further research. Having gathered all of the research information previously outlined, the emergency manager is ready to assign a frequency score to the event in question. Each potential event is scored from one to ten (see Figure 2), based upon the historical incidence of local, regional and national occurrence, with ten being the most highly probable locally occurring event, and one being a vague potential for occurrence at some point. The next phase in the process is the “vulnerability assessment”. Vulnerability is assigned a score from one to ten (see Figure 3), with ten representing the most


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Figure 3. Impact Evaluation Scheme.

Figure 4. Social Consequence Evaluation Scheme.

serious and far-reaching effects on the community, and one being relatively benign. These scores are based upon the characteristics list in the Vulnerability Evaluation Scheme. An event must satisfy only one of the impact characteristics to receive the corresponding Vulnerability Score. In the final phase, “social consequences” are evaluated. Similar to earlier phases, a score from one to ten assigned to different level of social recognition of risk already identified and vulnerability assessed. This part of risk assessment should reflect social concepts and meaning of risk. In perspective of social meaning of the event and social consequences, it actually attempts to recognize variation in social acceptability of risk. In this part, emergency managers need to consult with potential victims and others to rank their priorities, considering the results of the previous risk assessment phases. The score are founded upon the characteristics noted in the Social Consequence Evaluation Scheme (Figure 4).

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Figure 5. Risk assessment table with scores.

Finally, the scores of the three Schemes are multiplied together, in order to arrive at a Risk Rating on a 0–1000 scale, and are plotted on the Risk Assessment Table (see Figure 5). This table provides guidance with respect to both mitigation and preparedness priorities. Those events receiving a score of 800 or more are highly probable, and have potentially very severe effects and community puts them at top priority. These should receive immediate mitigation and planning attention. Those scores between 500 and 799 represent events that may have severe effects but decreasing probability of occurrence, or a high probability of occurrence but decreasing effects. The community values these as moderate priority. These events should receive mitigation and planning attention in decreasing order, as resources become available to address them. The third group will have the score in the range between 200 and 490. These are frequent events with limited damage-potential or infrequent and characterized by comparatively less severe consequences. In these cases it is likely that the community would prefer to compare cost-effectiveness of the planning activities with other social priorities. The final group of events is those scoring from 1–199. These events are infrequent occurrences with minimal or no significant potential effects, and are the lowest priority for mitigation and planning purposes. Thus, the planning activities could be deferred but should not be ignored.


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Figure 6. Comparative risks - City of Toronto.

4.2. SCOPE AND QUALIFICATIONS The use of this method of assessing risk provides several advantages to the emergency manager. The proposed methodology provides a tool for the evaluation as well as the comparison of relative risks to the community from very different phenomena, such as tornadoes and winter storms (see Figure 6) using a standard set of criteria. This method of risk assessment also permits the comparison of relative risk from both natural and technological hazards (Ferrier, 2000). This permits the emergency manager to establish a set of priorities, in collaboration with the community members, for mitigation, planning, and preparedness. The process is partially similar to one generally called ‘risk mapping’, which is in common usage by private sector business continuity planners. Moreover, the application of numeric values to risk also means that data can be plotted graphically, in order to identify areas or groups at particular risk. Another extremely useful tool is the geocoding and spatial plotting of data (Ferrier, 2000), using cartography software such as MapInfo, in order to identify locations and groups at particular risk, and to correlate existing planning and demographic data, in order to better plan interventions. To illustrate, if the emergency manager knows that a particular hazard, such as heat waves, poses particular risk for those over age 65, the distribution of these subsets of population may be displayed (see Figure 7) for analysis and planning. As this process progresses, other planning information such as school locations may be added, in order to identify both needs and resources. The methodology used, while not absolutely precise, is flexible enough to be used and understood by both emergency managers, who generally come from a variety of disciplines and levels of education, and by both the public and policy makers. Additionally, it becomes possible to apply information gather by this process to population projections, in order to forecast possible changes in community impacts. Another major merit of the proposed risk assessment scheme is that it is flexible and thus could be employed to adjust to a given situation. Although it is not recom-

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Figure 7. Identifying groups at risk: One example.

mended, only the first two phases of the scheme could be adopted at times of “rush” or if resource does not permit community-based social consequence evaluation. There is not doubt that such an elimination of the social evaluation scheme would put limits on the social feasibility of emergency manger’s plans and actions. As a working framework, the proposed risk assessment scheme only with two phases (risk identification and vulnerability assessment) would still be effective. While there are clear advantages to adopting this methodology, certain issues remain to be addressed. There may be those who suggest that the use of a worst-case scenario creates an assessment of impacts that is somewhat exaggerated, resulting in a response to the emergency that is larger and costly than required. Those making this criticism are reminded that an emergency manager’s definition of a disaster is generally “any incident that creates one more issue than I have the resources to deal with”. Excess resources resulting from an overestimation of impacts can always be held in reserve, or utilized in other ways. From an emergency management perspective, it is better to have too many resources than not enough. It should be kept in mind that the methods outlined in this proposed scheme are primarily intended as a methodology for the identification of risk, and for the setting of planning priorities by practitioners of emergency management, not the scientific community.


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What are being calculated are the event’s potential effects, rather than the details of occurrence. There may also be those who might suggest that the impact characteristics in this method of risk assessment are insufficiently objective. While this may be an accurate observation, one should consider that the impact characteristics used by this method at least provide a standardized set of guidelines for estimates. This represents a substantial improvement over the current ‘seat of the pants’ or post event approaches to assessment, neither of which permits the emergency manager to be pro-active in either emergency planning or resource acquisition. In the earliest stages of this process it may well be that such a methodology will suffer from insufficient local information. It may even appear that the required research is too time consuming to be worthwhile. This may be attributable to poor local record keeping, but is more often the result of poor record storage, or of a poor understanding of the value of the data. The systematic use of this proposed approach to assessment should highlight areas of little known local history and identify other information about the community that may not be commonly known. A great deal of information is generally available, but may not be immediately recognized. This underscores the importance of the role of the emergency manager in the capture of community experiences. These experiences include information such as reception centre registrations, emergency services call data, and survivor interviews. Due to difficulties in obtaining the information, some of these sources are not normally explored by the scientific community. While a considerable effort is required initially, the information can be used repeatedly, once it has been discovered and catalogued. Some information may simply be very difficult to obtain and collate. This may be especially true for some groups at particular risk, such as those with disabilities. While various support organizations attempt to keep data, it is generally limited to those with one particular challenge. Therefore, emergency managers must obtain data from a variety of different sources, some of which may create duplications of information. This situation could be adequately addressed through the capture of the required data as a part of the national census.

5. Conclusion Many aspects of the practice of emergency management are dependent upon accurate and realistic risk information. The media and common misconceptions often shape the public’s perception of risk; a situation that the emergency manager must have the tools to change. Additionally, the identification of risks and assessment of human vulnerability becomes matters of hindsight for emergency managers far too frequently. Tools that help the emergency manager’s efforts at effective and pro-active planning would help to remedy this situation. Emergency exercises and training programs for emergency responders are directly dependent upon an understanding of real risk exposures. Pre-emergency

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education efforts with the public, and the acquisition of appropriate types of response resources should also reflect the real risks faced by the community. Training programs and public information not based upon real potential risk will lack credibility. There is also a danger that requests for the acquisition of response resources will be denied, if the business case for such acquisitions is not supported by the community at large or is not based upon enhancing the community’s ability to respond to real, credible risks. Emergency managers require a common methodology and framework which are sufficiently flexible to be used by a variety of sources. Such a system will permit more effective identification and comparison of relative risks and vulnerabilities, and will also permit communication of those risks with the community for the planning of mitigation and response efforts. The methods proposed here will provide the tools required. One of the greatest challenges in making this proposal succeed involves the movement and sharing of information. A considerable volume of the technical information required to drive this process is already available within the scientific/academic community, but is poorly understood by both policy makers and the general public. Both scientists and emergency managers tend to function in isolation from one another, and contact between the two groups is infrequent. The potential exists for the scientific community to use the emergency manager a communicator of risk, in much the same manner that profession science writers are now used. In a similar fashion, the emergency manager has the potential to become a valuable source of local information for those conducting research. Clearly, a partnership between the scientific/academic community and the emergency management community is required. Before potential benefits can be realized, however, the linkages between the scientific community and the practitioners of emergency management must be improved. This could and should occur through the provision of research internships to senior students from the ’hard’ and social science disciplines by the emergency management community. Canada also requires the establishment of interdisciplinary undergraduate and graduate programs in emergency management in Canada’s universities. While a great deal of the community composition information required to drive this methodology is available at the local level, and more through the Census data, the information on community composition is incomplete. The Census of Canada should be changed in order to capture more of the needed information, particularly on people with disabilities, in a manner that is both less confusing and more scientifically acceptable. Additionally, much of the historical information required to drive this methodology is available within the local community, although much of it may be difficult to find, poorly understood, or not even recognized as history. This underscores the importance of the emergency manager in helping a community to capture and document its own experiences and history. This includes the capture of information from previous emergencies, in order to prepare for the next.


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Canadian communities must form and strengthen the linkages between the scientific/academic community and the community at large, so that information can be gathered, and risk can be effectively communicated. This will permit all stakeholders to develop appropriate community preparations and mitigation strategies, in order to minimize the loss of life and property through natural and technological disasters. The community’s emergency manager, using the proposed methodology, can play a pivotal role in helping this identification and communication of risk to occur.

Acknowledgement The authors gratefully acknowledge Laurie Pearce, University of British Columbia, Vancouver, Canada, for providing constructive criticisms and comments on an earlier draft of the paper.

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