Research and Evaluations of the Health Aspects of ... · Chief, Prehospital and Disaster Medicine 2. Nursing Section Editor, Prehospital and Disaster Medicine; Executive Secretary,

Research and Evaluations of the Health Aspects ofDisasters, Part II: The Disaster Health ConceptualFramework Revisited

Marvin L. Birnbaum, MD, PhD;1 Elaine K. Daily, BSN, FCCM;2 Ann P. O’Rourke, MD, MPH;3

Alessandro Loretti, MD4

1. Emeritus Professor of Medicine andPhysiology, School of Medicine and PublicHealth, University of Wisconsin, Madison,Wisconsin USA; Emeritus Editor-in-Chief, Prehospital and Disaster Medicine

2. Nursing Section Editor, Prehospital andDisaster Medicine; Executive Secretary,World Association for Disaster andEmergency Medicine, Madison,Wisconsin USA

3. Assistant Professor, Division of GeneralSurgery, Department of Surgery, School ofMedicine and Public Health, University ofWisconsin, Madison, Wisconsin USA

4. Retired, World Health Organization;Consultant, World Association forDisaster and Emergency Medicine,Adelaid, South Australia, Australia

Correspondence:Marvin L. Birnbaum, MD, PhDSuite 407610 N. Whitney WayMadison, WI 53705 USAE-mail: [email protected]

Conflicts of interest: Some of the concepts,contents, and text provided in this report weredeveloped in association with Knut OleSundnes, MD, and evolved from the HealthDisaster Management: Guidelines for Evaluationand Research in the Utstein Style.a Initial andpartial support for this project was provided bythe Task Force for Quality Control of DisasterManagement.

Abstract: A Conceptual Framework upon which the study of disasters can be organized isessential for understanding the epidemiology of disasters, as well as the interventions/responses undertaken. Application of the structure provided by the Conceptual Frameworkshould facilitate the development of the science of Disaster Health. This Framework isbased on deconstructions of the commonly used Disaster Management Cycle. TheConceptual Framework incorporates the steps that occur as a hazard progresses to a dis-aster. It describes an event that results from the changes in the release of energy from ahazard that may cause Structural Damages that in turn, may result in Functional Damages(decreases in levels of function) that produce needs (goods and services required). Theseneeds can be met by the goods and services that are available during normal, day-to-dayoperations of the community, or the resources that are contained within the community’sResponse Capacity (ie, an Emergency), or by goods and services provided from outside ofthe affected area (outside response capacities). Whenever the Local Response Capacity isunable to meet the needs, and the Response Capacities from areas outside of the affectedcommunity are required, a disaster occurs. All responses, whether in the Relief or Recoveryphases of a disaster, are interventions that use the goods, services, and resources containedin the Response Capacity (local or outside). Responses may be directed at preventing/mitigating further deterioration in levels of functions (damage control, deaths, injuries,diseases, morbidity, and secondary events) in the affected population and filling the gaps inavailable services created by Structural Damages (compromise in available goods, services,and/or resources; ie, Relief Responses), or may be directed toward returning the affectedcommunity and its components to the pre-event functional state (ie, Recovery Responses).Hazard Mitigation includes interventions designed to decrease the likelihood that a hazardwill cause an event, and should an event occur, that the amount of energy released will bereduced. Capacity Building consists of all interventions undertaken before an event occursin order to increase the resilience of the community to an event related to a hazard thatexists in an area-at-risk. Resilience is the combination of the Absorbing, Buffering, andResponse Capacities of a community-at-risk, and is enhanced through Capacity-Buildingefforts. A disaster constitutes a failure of resilience.

Birnbaum ML, Daily EK, O’Rourke AP, Loretti A. Research and evaluations of thehealth aspects of disasters, part II: the disaster health conceptual framework revisited.Prehosp Disaster Med. 2015;30(5):523-538.

Keywords: conceptual framework; disaster;health; resilience; risk

Abbreviations:CMR: crude mortality rateUN: United NationsUN-ISDR: United Nations InternationalStrategy for Disaster Reduction

Received: April 14, 2015Accepted: June 6, 2015

doi:10.1017/S1049023X15005130

a Task Force for Quality Control of DisasterMedicine, World Association for Disasterand Emergency Medicine, Nordic Societyfor Disaster Medicine. Health DisasterManagement Guidelines for Evaluation andResearch in the Utstein Style. Sundnes KO,Birnbaum ML (eds). Prehosp Disaster Med.2003;17(Supplement 3).

SPECIAL REPORT

October 2015 Prehospital and Disaster Medicine

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IntroductionA Conceptual Framework is essential to understanding anddescribing the epidemiology of disasters. Its use also provides thestructure needed to study disaster-related interventions. ThisConceptual Framework describes and defines a stepwise progres-sion from a hazard to a disaster and associated opportunities toincrease a community’s ability to cope with an event.

The original Conceptual Framework described in HealthDisaster Management: Guidelines for Research and Evaluation in theUtstein Style1 (hereafter referred to as “the Guidelines”)represented the thinking at the time it was published in 2003.However, in keeping with the knowledge that has been gained inthe ensuing 12 years, and in order to bring the ConceptualFramework into concordance with the missions of HumanitarianReform,2 the United Nations (UN) International Strategy forDisaster Reduction (ISDR),3 the Transformative Agenda ofthe UN Inter-Agency Standing Committee (IASC),4 theGlobal Platform (2013),5 and the Sendai Framework forDisaster Risk Reduction, 2015-2030,6 the original ConceptualFramework has been deconstructed further and modifiedaccordingly.

Although the Disaster Management Cycle7 has been used todescribe disasters for decades, its limited nature is inadequate forthe research and evaluation required to build the science ofDisaster Health. The Disaster Cycle (Figure II-1) doesnot include phases related to time, but rather stages that aresequential—one stage ends before the next stage begins. Thestages include the occurrence of an event, which promptsresponses to cope with the damages created by the event, and toalleviate suffering, reduce mortality, and minimize the damagescreated by the event.

Given the current emphasis on disaster risk reduction and riskmanagement,2-6 the long-standing Disaster Cycle is an insuffi-cient framework for describing, studying, and reporting ondisasters. Some definitions have morphed and no longer fit intothe initial model. For these reasons, it is necessary to deconstructthe Disaster Cycle Model into its subcomponents, and to redefinesome of the terms used. This deconstruction led to a revisit of theinitial Conceptual Framework as described in the Guidelines,1 andthe development of a more comprehensive and discriminatingConceptual Framework. The use of the proposed enhanced

Conceptual Framework should aid in obtaining a greater clarity ofthe epidemiology of disasters and for comparing events,emergencies, and disasters as well as the interventions imple-mented. It also may be applied to studying events that do/did notresult in an Emergency or a Disaster.

Community, Society, and CultureDisasters occur at the “community” level.5 A community is a groupof people living in the same locality and under the same govern-ment; the district or locality in which a group lives.8 For thepurposes of this work, a community is interpreted as an urban orrural population and environment acting as a whole that is served bya government that attempts to meet the needs of the populationgoverned. Communities may be part of an over-riding society ormay have several societies within a community. A society is thetotality of social relationships among humans; a group of humansbroadly distinguished from other groups by mutual interests, par-ticipation in characteristic relationships, and a common culture.9

Most societies have a specific culture. The culture of a societyconsists of the arts and other manifestations of human intellectualachievement regarded collectively; the customs, civilization, andachievements of a particular time or people;10 the totality of sociallytransmitted behavioral patterns, arts, beliefs, institutions, and allother products of human works and thoughts; the predominatingattitudes and behavior that characterize a group or organization.11

Generally, a society consists of many communities or parts ofcommunities. A community may be an amalgam of multiplecultures. A community may be an individual, neighborhood, town,village, city, county, province, state, country, and so on.

Communities exist to provide the common, essential functionsrequired to meet the needs of the population served by thecommunity. Failure to provide these functions results in needs.Thus, the levels of disfunction of a community or its componentsresult in needs.

The structure of a community provides the goods and servicesthat are transformed into societal functions. The transformationprocesses require access to the resources that are used in thetransformation of goods and services into functions. Theconsequences of any event on a community are what happen to thefunctional status of the community or its components.

For research and evaluation purposes, communities have beendeconstructed into 14 functional systems that mostly correspond tothe departmental structures of communities (if they exist). Asdeveloped in the accompanying paper on Societal Systems,12 theseSocietal Systems are dependent upon one another for functions thatare not part of the individual Societal System; each requires goods,services, and other resources in order to provide the functions for itsoperations. For example, the Medical Care System is dependent onthe Energy Supply and Logistics and Transport Systems for fueland electricity; compromise of the functions of these Systems willprofoundly affect the ability of the Medical Care System to delivermedical services to the affected population. Each of the SocietalSystems must have access to the goods, services, and other resourcesit requires to provide the required levels of function.

For the most part, the functions provided by a community(and each of its component Systems) are relatively constant overtime—a community exists in a relative steady state. Communitiesnormally are exposed to many hazards, but they are able to managethe hazards with only minor changes in their levels of functions—they work to maintain stability. Changes in the steady state of acommunity usually require relatively long periods to implement.

Birnbaum © 2015 Prehospital and Disaster Medicine

Figure II-1. The Classic Disaster Management Cycle. Thiscycle illustrates the progression from mitigation of the hazard,to preparedness to respond, to the occurrence of an event, tothe response to the event, and recovery to the pre-event levelsof function.

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524 Disaster Research Evaluation/Frameworks, Part II



Each community has a specific level of resilience to events relatedto their specific set of hazards. Each community is at-risk that thecompromised functions that result from an event caused by ahazard will overwhelm its overall resilience, or that of any of itscomponents. When the resilience of any component of thecommunity to an event is overwhelmed, a Disaster has occurredfor that community, or the part(s) of the community(ies)that is(are) affected. Disasters are the result of events that over-whelm the relative functional steady state of the communityimpacted by an event. The Conceptual Framework is a means forevaluating the processes that take a hazard to a disaster.

Conceptual FrameworkThe deconstructed and redrafted Conceptual Framework(Figure II-2) describes and defines the process and elements thatlead from a hazard to a disaster and provides the structure neces-sary to understand how a hazard evolves into a Disaster. It includesand expands all of the components in the Disaster ManagementCycle model.7

Hazard(s)Every disaster is related to a specific hazard or combinations ofhazards, whether the hazard is a natural phenomenon or result ofhuman actions. A hazard is a dangerous phenomenon, substance,human activity, or condition that may cause loss of life, injury, orother health impacts, property damage, loss of livelihoods andservices, social and economic disruption, and/or environmental

damage.1(pp31-42) A hazard may be described as contained(potential) energy. The danger posed by a hazard relates to thepotential energy it contains. All things that contain potentialenergy are hazards. Hazards are classified by type and as naturallyoccurring or human-made (anthropogenic; Table II-1 andTable II-2). Natural hazards are part of nature; they includeseismic faults and volcanoes, the weather (meteorological orclimatic), and biological (bacteria, viruses, fungi, and toxins).Human-made hazards are those that result from human actions,and may be classified either as technological or related to humanbehavior(s).

Hazards contain potential energy. Energy is the capacity to dowork.13 Energy may be translated into motion, overcomingresistance, or by producing physical or psychological changes.The types of energy contained within a hazard are specific for agiven hazard. Six types of physical energy are relevant to DisasterHealth: (1) mechanical (M); (2) electrical (E); (3) thermal (T);(4) chemical (C); (5) nuclear (N); and (6) biological (B; Table II-1and Table II-2). Mechanical energy manifests as physical forces.Electrical energy is related to the movement of free electrons andmay be naturally occurring (ie, lightening) or generated by humantechnology, and may manifest by release of thermal energy (fire).Thermal energy relates to the speed of the movement of moleculesand manifests as heat or cold. Chemical energy is released throughchemical reactions. Nuclear energy is released by modification ofnuclei (nuclear reactions). Biological energy relates to themetabolic capacities of organisms to change some combination ofbiomass, organic compounds, gases, and water that changeschemical bonds (eg, photosynthesis, adenosine triphosphate, cellreproduction, and cell damage).14 Psychological energy has thecapacity to change behaviors and includes inter-human relation-ships, including economics. Behavioral hazards may use physicalforms of energy to create changes in behaviors.

Some of the energy contained in many hazards is harnessed foruse by the community to benefit the population. Some forms ofenergy are used to produce goods and services used by the popula-tion. Some of the energy is converted by the community into otherforms of energy. For example, the effects of gravity onwater are usedfor the generation of electricity. Wind is converted into electricalenergy or for pumping water. Thermal energy from the sun is usedto heat water or to generate electricity. However, when such energyis used by a community, too much may become destructive, as cantoo little. Inadequate amounts of energy alsomay disrupt the normalbalance and may impair the development of goods and servicesrequired to sustain the balance of the community. Precipitation isrequired to grow crops and for hydration of living beings. Toomuchprecipitation may cause floods or mudslides, and too little results inthe development of drought and its negative effects on agricultureand food production. Structures built by humans must be able towithstand the forces exerted by gravity. When possible, humansattempt to control the amounts of energy used. Failure to controlthe amount of energy produced often creates events that causestructural damage to the community. Thus, hazards generally are inbalance with the needs of the community.

The specific hazards to which humans are exposed vary in spaceand time, and between different populations. A hazard thatdoes not produce an event cannot cause a disaster. Without theoccurrence of an event from a specific hazard, an existing hazardmay not be recognized. Consequently, hazard identification isessential in the development of definitive preventive or mitigatingmeasures.


Figure II-2. The Revised Conceptual Framework for aHazard Evolving into a Disaster. Functional damage consistsof compromised functions of the community caused bystructural damage. Functional damages are transformed intoneeds. All responses address identified needs by providing thegoods, services, and other resources required to meet thedefined needs. Three levels of responses are included:(1) Ordinary; (2) Extra-ordinary; and (3) Outside. Responsesare directed at relief or recovery and provide resources forrepair or replacement of structures damaged by the event, orto temporarily supplement the gaps in levels of functionscompromised by the structural damages.


Birnbaum, Daily, O’Rourke, et al 525



Hazard Mitigation (Figure II-3)—Hazard Mitigation involvesefforts (actions) to reduce the risk that the hazard will cause anevent, or if an event occurs, mitigate the power of the event tocreate damage.While most natural hazards do not lend themselvesto modifications or containment, some interventions cansuccessfully mitigate the destructive energy of anthropogenichazards. The magnitude of a future event may be mitigated by:(1) eliminating the hazard; (2) modifying the hazard; (3) con-taining the hazard; and/or (4) identifying an alternate source of the

energy. These mitigation actions attempt to reduce the likelihoodof the occurrence of an event or to reduce the magnitude of apotential event. Examples of mitigating a hazard throughelimination of the hazard include: (1) removing landmines; and(2) achieving and sustaining peace between hostile parties.Examples of modifying a hazard include: (1) chemically or phy-sically altering a hazard to decrease its power to cause damage;(2) controlling avalanches by the pre-emptive firing of canons;(3) augmenting the safety of motor vehicles and providing safe

Hazard Classification Hazard Primary Event Secondary Event Type of Energy

Seismic Fault Earthquake Tsunami M

Volcano Eruption Tsunami M

Gravity Collapse M

Precipitation M

Mudslide M

Landslides M

Mudslides M

Floods M

Meteorological Climate Wind High Wind M

Precipitation Rain Floods M

Mudslides M

Drought M,T

Snow Floods M

Avalanches M

Ice/Hail/Sleet Collapse M

Lightning Fire Collapse T,M

Collapse M,E

Sun Excess Heat T

Cold T

Radiation N

Biological Bacteria, Viruses, Fungi, Toxins Disease B

Epidemic

Pandemic B

Nuclear Radium Contamination N,C

Other

Combined Sun, Decreased Water Drought T

Wind, Rain, Storm Surge Cyclone MBirnbaum © 2015 Prehospital and Disaster Medicine

Table II-1. Classification of Natural Hazards, the Events that may be Produced, and the Types of Energy Released fromthe HazardAbbreviations: B, biological; C, chemical; E, electrical; M, mechanical; N, nuclear; T, thermal.





highways and byways; (4) cooling nuclear reactors with water;and/or (5) minimizing the numbers and quantities of hazardousmaterials. Examples of containment of a hazard include: (1) safelydisposing hazardous wastes; (2) enforcing laws relative to the safemanagement and transport of hazardous materials; (3) encasing anuclear source; (4) educating and training workers in hazardousareas; and (5) implementing safety measures to prevent leakageof oil from wells. All of these actions represent attempts tomitigate a hazard. In the case of insufficient energy to provide theneeded goods and services, alternate sources of the energy required

should be identified and appropriate arrangements made foracquisition, if needed.

It should be noted that most of the discussion that followspertains to events in which there is an excess of energy that impactsa community.

EventAn event is an occurrence that has the potential to affect livingbeings and/or their environment.15 An event consists of thechange in the amounts of energy released by the hazard that results

Hazard Classification Hazard Primary Event Secondary Event Type of Energy

Technological Chemical Explosion Collapse M

Injury M

Fire Collapse M

Contamination C

Contamination C

Release/Spill C

Structure Collapse M

Electricity Fire T,E

Power Failure

Transport Crashes M

Release/Spill C

Nuclear Reactors Release/Spill Contamination N

Reservoir Rupture Flood M

Biological Agents Contamination Epidemic B

Pandemic B

Human Interactions Armed Conflict Civil Strife, Unrest M,P

Complex Emergency M,P

Terrorism M,P

Other

Unarmed Conflict Behavioral Terrorism P

Incarceration P

Torture M,P

Ethnic Cleansing M,P

Economy Embargo Econ

Sanctions Econ

Bankruptcy EconBirnbaum © 2015 Prehospital and Disaster Medicine

Table II-2. Classification of Human-made Hazards, the Events that may be Produced, and the Types of Energy Released fromthe HazardAbbreviations: B, biological; C, chemical; E, electrical; Econ, economic; M, mechanical; N, nuclear; P, behavioral/psychological; T, thermal.





in perturbing the steady state of the community. An event disruptsthe balance normally sustained by the community. It consists ofeither too much or too little kinetic energy. The transfer of theenergy may impact living beings, the environment, and/or builtstructures. Most events are managed by the routine (ordinary),day-to-day activities of the community and do not result in anemergency or disaster.

Generally speaking, the events that lead to a disaster have notbeen characterized sufficiently to facilitate comparisons betweenspecific events, and in turn, this limits the ability to understandthe mechanisms involved and their respective consequences.However, in order to increase the understanding and facilitatecomparisons, events should be described using consistentterminology. The following discussion provides event descriptorsthat are considered to be relevant and useful to the study andreporting of disasters.

Description of an Event—The characteristics of an event arenumerous; some of the characteristics of an event have beendescribed previously in the Guidelines.1 However, the inventoryof characteristics has been expanded and is provided inTable II-2. Events are compared by their respective characteristics.

Description of the characteristics of the event include the: (1) typeof energy (mechanical (M), biological (B), thermal (T); chemical(C), electrical (E), nuclear (N); behavioral/psychological (P));(2) mechanisms; (3) number of events; (4) onset; (5) amplitude;(6) duration; (7) intensity; (8) scope; (9) magnitude; (10) scale;(11) progression; and (12) propagation.

Type of Energy—The events caused by naturally occurringhazards include those related to: (1) seismic hazards (M), includingearthquakes, volcanic eruptions, tsunamis, and gravity;(2) meteorological (climatic) hazards, including high winds (M),excess or lack of precipitation (M), fire from lightening (E),temperature extremes (T), erosion (M), drought (T), desertification(M), floods (M), avalanches (M), and mud/landslides (M);(3) disease caused by biological agents, including bacteria, viruses,fungi, and toxins (B); and (4) celestial phenomena (M,N,T).Human-caused hazards may produce technological events as aresult of: (1) the release of chemical, biological, or nuclearsubstances; (2) transportation incidents, such as aircraft crashes ortrain derailments; (3) structural failures, such as collapses of build-ings; (4) explosions; (5) fires; (6) environmental interference withnature; and (7) activation of other hazards (secondary events).Additional human-caused events include those related to beha-vioral/psychological activities: (1) terrorist acts; (2) wars (armedconflicts); (3) complex emergencies; (4) political actions; and(5) economics, such as market failures, embargos, and sanctions.Table II-1 and Table II-2 list examples of events associated withspecific hazards. Some events may be the result of a combination ofnatural and human-made hazards (eg, drought related to themisuse/diversion of water; desertification due to weather andinappropriate grazing of livestock; floods related to excessprecipitation and improper engineering of waterways; erosion dueto poor management of shorelines; land/mudslides and avalanchesrelated to a combination of precipitation and deforestation; andfires caused by human carelessness or poor safety practices). Someof these events have special features that may lead to secondaryevents.

Mechanism—The mechanism responsible for the release of theenergy should be documented if it is relevant to the description ofthe event. A description of the mechanism responsible for theevent not only contributes to the understanding of theepidemiology of the disaster, but also provides valuable informa-tion regarding potential mitigation efforts. Essentially, how andwhy did it happen?

Number of Events—Events may occur singly or in multiples.The earthquakes in Pakistan and in Christchurch, New Zealand in2011 were single, isolated events. However, each was followed by aseries of “aftershocks” that contributed to the damage. Similarly,multiple tsunami waves impacted Indonesia following the earth-quake in the Indian Ocean in 2004. From a medical/public healthperspective, an explosion of a bomb during a terrorist attack is asingular event, but if multiple bombs explode almost simulta-neously (eg, the Madrid train attacks (2004), the BostonMarathon attacks (2013), and the London Subway bombings(2005)), each is considered to be an individual event.16-20

Multiple events may occur simultaneously (in parallel) or may besequential. Tropical cyclones (hurricanes) consist of three events:(1) high winds; (2) heavy rain; and (3) a storm surge thatoccur almost simultaneously. Multiple events also may consistof primary, secondary, or tertiary events. A primary event isthe initial event (eg, earthquake) that may initiate a secondaryevent (eg, tsunami), which, in turn, may initiate a tertiary event


Figure II-3. The Conceptual Framework with the Additionof Local and Outside Absorbing, Buffering, and ResponseCapacities. Responses that require the use the extra-ordinary(reserve) local response capacity comprise an “emergency” forthe community. When responses must include the responsecapacities of other entities, the situation becomes a “disaster.”In addition, structural and functional damages that occur inother systems may result in needs within the system(s) beingstudied. Together, the absorbing, buffering, and responsecapacities comprise the resilience of the community to anevent. Capacity building interventions are directed towardsincreasing the resilience to the event, and risk-reductioninterventions include capacity building and hazard mitigation.Abbreviations: Ex, extraordinary; Or, ordinary.





(eg, Fukushima nuclear reactor meltdown (Japan 2011)). Both thesecondary and tertiary events occur only as a result of the primaryevent. Famine may be a secondary event as a result of three primaryevents: drought, desertification, and conflict.

Onset—An onset is the beginning of something;21 in termsof an event, the onset begins at the time the event(s) is(are)recognized. Documentation of the characteristics of the onsetis essential for comparisons of events and their respectiveconsequences. The time of the day, the day of the month, and themonth of the year of the onset must be documented as well as theexisting local conditions (day, night, weather, holiday, weekend,and so on) at the time of the onset of the event are importantfeatures of the event. The geographical location and itscharacteristics may have important implications and also must bedocumented. The rate of energy change from onset includessudden burst, crescendo, and decrescendo. Delayed onset refers tothe ability to predict the onset of an event prior to its impact onan area (eg, a tropical cyclone approaching a coastal area). Suchpredictions facilitate the evacuation of the population prior to theonset of the event in order to decrease their exposure to the event.Did the earthquake happen during the night when the populationwas sleeping in their homes or during the day when they were onthe streets, at sea, or in the fields?

For the purposes of comparison, a description of the event alsoshould include the: (1) amplitude; (2) duration; (3) intensity;(4) scope; (5) magnitude; (6) scale; (7) progression; and(8) propagation.

Amplitude—The amplitude is the degree of departure from thepoint of equilibrium; the maximum displacement or distancemoved by a point on a vibrating body or wave measured fromits equilibrium position (ie, the pre-event state).22 Generally,amplitude is considered to be the maximum change in the strengthof the energy exerted (eg, the maximum deflection of a seismo-graphic tracing, the height of a storm surge, the wave height, themaximum number of persons infected by a pathogen, or thedeparture of the temperature for the time of the year).

Duration—The duration is the length of time over whichsomething continues.23 While the total duration of an eventencompasses the entire length of time over which the event occurs,it may be subdivided into time segments. In general terms, theduration of an event may be described as: (1) Brief (seconds tohours); (2) Short (hours to days); Intermediate (days to weeks); or(4) Prolonged (months to years).1(pp31-42) However, these basicdescriptors are inadequate for use in comparison of events. Whenpossible, the actual time interval over which the event occurredprovides information required for comparisons (eg, the earthshook for 10 seconds or for three minutes). To date, the durationof earthquakes has been reported only rarely, although the differ-ences in the structural damage produced by an earthquake thatlasted three minutes likely would differ substantially from one ofequal amplitude that lasted only 10 seconds.

Intensity—The intensity of an event is the integral of its ampli-tudes over a given period of time (Σamplitudes/time interval).24 Forexample, the intensity of an event may be reported as millimeters ofrainfall/hour; inches of snow accumulation/hour; centimeters offloodwater level/day; or degrees of temperature change/week.

Scope—The scope of an event is the extent of the area of subjectmatter that something deals with or to which it is relevant;25 thearea covered by a given activity.26 In terms of a disaster, scoperefers to the area affected by an event. Examples include the geo-graphical extent of the incident, or the number of persons affected

by a specific infectious disease in a country; and/or the number ofhectares within a specific location under water due to flooding.

Magnitude—The magnitude of an event is a measurement ofthe amount of an applied force; the amount of energy released;27 amathematical quantity.28 Magnitude refers to the total energyencompassed by the event in the area being studied, and is thecombination of the integral of the amplitudes, the area involved,and the total duration of the event. An example is the total rainfallaccumulated over a specific area during the entire course ofa storm.

Scale—In the context of disasters, scale includes the scope andmagnitude of an event or damage sustained from an event. Itseems that the term is used most frequently to describe the damagecreated by an event, but gets lost when describing the event as thedisaster (“large-scale disaster”). Scale is used best in descriptions ofthe area and magnitude of the structural damage.

Progression—An event may occur in a continuous fashion (ie,stay at one level of energy release for its duration), it may beascending (crescendo) or descending (decrescendo) in nature, or itmay be nodal/pulsatile. A “steady” rain may have the same inten-sity throughout its entire duration, or the precipitation may wax orwane, with the intensity changing from light to heavy to moderateto light, and so on. The latter occurrence may be described asnodal or pulsatile. It is of value to report the duration of each of thenodes as well as the inter-nodal periods, such as the frequency ofvolcanic eruptions. A richer description of a tsunami includes thenodal nature of the energy of differing amplitudes and frequency.Additional useful information about an earthquake is thefrequency of the pulsatile release of energy.

Propagation—To propagate is to disseminate; spread; to extendthe operation of; transmit (a vibration, earthquake, or others).29 Inthe context of an event, “propagation” is used to describe thespread of energy from its source. For example, the energy of anearthquake spreads from the epicenter. The spread, transmission,and damping of the energy of an earthquake depend on the natureof the earth through which the energy travels. The spread andtransmission of a disease varies, in part, according to the herdimmunity of the population.

Consequences of an EventA consequence is a result or effect of an action or condition.30 Eachstep in the progression of a hazard to a disaster has a consequence orset of consequences. Thus, Structural Damage is a consequence ofan Event, and Functional Damage is a consequence of the Struc-tural Damage. Needs are consequences of Functional Damage, anda Disaster is a consequence of Needs that exceed the local responsecapacity. Consequences can be considered as the effects of a process.It is essential to be able to compare the consequences of an eventwith the characteristics and setting of the event. The consequencesassociated with the progression of a hazard to a disaster include:(1) Structural Damage; (2) Functional Damage; (3) Needs;(4) Emergency; and (5) Disaster. Each of the consequencesis detailed below.

Structural Damage (Figure II-2 and Figure II-3)—Damage isharm or injury that reduces the value or usefulness of something.31

Structural Damage consists in disturbances in the structures thatcomprise the community—not just physical structures, but includesdisruption of the balance of the community and in its ability toprovide the goods, services, and other resources essential to





maintain the functions of the community. Thus, StructuralDamage impairs the availability of the goods, services, and resourcesnecessary to provide the essential functions of the community—lackof essential goods, services, and resources results in decreases in thelevels of function provided to the population by the community. Anevent may or may not produce structural damage.

Structural damage includes the physical disruption of structure(s)that results from the transfer of energy released during an event intothe exposed structure(s). Structural damage occurs when thestructural integrity of the structure exposed is disturbed (violated)—a building collapses due to its impaired ability to resist the forcesexerted by gravity. Structural damage may occur to humans and/orother living beings, as well as to the natural and/or built environment(including equipment and supplies).1(pp56-68) Factors that determinethe likelihood (vulnerability) that damage to the physical structuremay occur from an increased kinetic energy from an event include:(1) exposure to the kinetic energy released; (2) the characteristics ofthe event(s); (3) the setting in which the event occurs; (4) the time ofonset including the hour of the day, day of the week, and the seasonof the year; (5) the weather; and (6) other hazards that co-exist withinthe impacted area.32,33 The end result is failure of the community toprovide the goods, services, and resources needed to maintain theconversion of the goods, services, and resources into functions.

Exposure—Exposure is the state or condition of beingunprotected or open to damage, danger, or risk of suffering aloss.34 A community/population/individual that is not exposed toa hazard will not sustain structural damage from an event causedby the hazard. In order to be damaged by an event, the communityand/or its components must be exposed to the event. A commu-nity that is exposed to a specific hazard or multiple hazards isreferred to as a “community-at-risk.”Exposure to some events maybe eliminated by moving a population-at-risk prior to a delayed-onset event (evacuation), or by permanently moving a settlementout of an area-at-risk (relocation).

Characteristics of the Event—The characteristics of the event(s), as previously described, directly affect the likelihood (prob-ability, risk) that an event will produce structural damage. Thetypes and amounts of structural damage are related to the type ofenergy of the event. The damage produced by mechanical energydiffers from the damages produced by biological energy or nuclearenergy. Also, for a given structure, the amount of damage pro-duced by an earthquake with a magnitude of 7.0 may differ sub-stantially from the amount of structural damage produced by anevent with a magnitude of 6.0. Additionally, the duration of anevent is an important contributing factor as the structural damagesustained is a function of the amount of energy released from thehazard influenced by the duration of the exposure to the event. Eightminutes of shaking during an earthquake likely will create morestructural damage than will an earthquake of equivalent magnitudethat lasts only 10 seconds. In addition, the frequency of the shakingwill impact heavily on the amount of damage sustained. This factorbecame evident in the analysis of the structural damage created bythe earthquake and the tsunami in the Indian Ocean in 2004,35 andfollowing the earthquake and tsunami in Japan (2011).36

Setting—The setting in which an event occurs affects the amountand types of structural damage that results. The setting includesthe: (1) geographical location; (2) community/population-at-risk;(3) infrastructure; (4) time of onset; and (5) vulnerability.

Location—The location of the area impacted, includingthe area’s geography, topography, geology, and weather, playsan important role in the dynamics associated with the event.

For example, the structural damages sustained from an earthquakemay depend, in part, on the nature of the ground (rigid, pliable, orsoft); the power of, and subsequent damage from, a storm surgemay depend on the characteristics of the shoreline; floodwaterlevels may depend on the nature of the ground, as well as thedrainage of an area prone to flooding. Human actions may changethe natural resilience of a geographic area. Examples includethe deforestation of hillsides and the overgrazing of livestock.Information on location also is essential in terms of access to thearea impacted.

Community/Population-at-risk—The characteristics of thecommunity/population-at-risk, including demographics, popu-lation density and distribution, culture, as well as the activities of thepopulation before/during the event, contribute to the vulnerabilityof the community. The specific location of the population withinthe affected area impacts its vulnerability; injuries from anearthquake are related to whether the population is inside of astructure, on the streets, or in the field tending to agriculture.Human activities at the onset or during an event also impact uponthe numbers of persons-at-risk for injury. While the fishermen atsea were not in harm’s way during the Southeast Asia tsunami of2004, the women and children who gathered at the seashore togreet them, or to prepare the catch for market, were in grave danger.A terrorist attack in a densely populated space is likely to injuremore people than if the attack is carried out in a rural area. Thenumber of persons directly in harm’s way contributes to the num-bers of persons injured/killed during an event. The demographics(eg, the average age of a population, immune status, and so on) alsomay contribute to the vulnerability of a population to an event.

Infrastructure—The constructions of the infrastructure,including types of residences, industries, governmental buildings,and/or medical facilities, are important indicators of vulnerability.As indicated in the photograph in Figure II-4, the vulnerability ofthe structures surrounding the mosque was much greater than wasthat of the mosque, which remained standing (able to withstandthe forces of gravity). The absorbing capacity of built structures hasa profound impact on the damage sustained.

Time of Onset—The time of onset, including the time of day,day of the week, and the season, have important implications forthe relative vulnerability of the population. Often, these indicatorsinform about where the population may be during the event.Existing weather conditions also impact the amount of damagesustained; the damage to humans may be different between anarctic region and a tropical one. Weather also is related to theshelter and clothing worn by the population and to the activities ofthe population.36 Population distributions often differ on theweekends and holidays compared to during the week. This also istrue in terms of the time of day an event occurs; nocturnal eventsoften impact the population inside their residences, while daytimeevents impact populations in their workplaces, in school, or on thestreets. Persons in bed during a nocturnal earthquake have a higherlikelihood of sustaining injuries from the collapse of buildings thando those out in the streets during the daytime.

Vulnerability—Vulnerability is a condition leading to higherrisk for damage due to the combined effect(s) of susceptibility,exposure, and coping ability.1(p145),37 It includes the characteristicsand circumstances of a community, system, or asset that make itsusceptible to the damaging effects of an event. While vulner-ability is related to the nature of the hazard responsible for theevent, it is not related to the process of the hazard evolving into





an event. The vulnerability of a society-at-risk corresponds to theStructural Damage, the subsequent Functional Damage (changesin function), and the ability of the community/population-at-riskto respond to the resultant needs. The vulnerability of thestructures impacted can be modified by human actions.

In summary, the loss (Structural Damage) of available goods,services, and other resources sustained from an event relates to thecharacteristics of the hazard, characteristics of the event, thevulnerability/resilience of the structures and population impactedby the event for the energy transferred, and the setting in whichthe event occurs.

Absorbing Capacity—Absorbing capacity is the ability to absorb allor part of the changes in the availability of energy and/or resourcesof an event without sustaining a decrease in the availability ofgoods, services, and/or resources (Figure II-5).1(p145) The like-lihood of sustaining structural damage from an event associatedwith excessive amounts of kinetic energy may be reduced byactions taken to augment the absorbing capacity of the structures-at-risk for the event. The greater the absorbing capacity of astructure for the energy contained in an event, the less the amountof Structural Damage sustained from a similar event (Figure II-5).If the absorbing capacity is sufficient to absorb all of the excess ofkinetic energy to which it is exposed, without the energy disrupt-ing the structural integrity of the structure, no Structural Damageto the structure will occur (eg, it will not collapse due to the forcesof gravity). For example, a heavy rainfall on land able to absorb thewater likely will not result in a flood. The event (heavy rainfall) wasnot prevented, but the absorbing capacity was able to minimize orreduce subsequent damage. Decreases in the absorbing capacityfor a potential event may be the result of human actions, or may

result from damage created by a previous event. For example, theabsorbing capacity for a flood may be decreased by deforestation oras a result of previous mudslides.38 Human actions that increasethe absorbing capacity for an event are part of capacity buildingefforts and contribute to the state of resilience to cope with a futureevent (Figure II-3). It must be noted that direct injuries may beproduced from the secondary events, such as collapse ofbuildings, from drowning or collisions against fixed structures, orfrom floating debris due to excessive force of the water during atsunami.

Every structure has a specific absorbing capacity for thecharacteristics of the energy released during an event or to resista decrease in kinetic energy supply or available resources. Thosestructures with the lowest absorbing capacity will have the highestlikelihood of sustaining damage from the kinetic energy of theevent (ie, have the highest vulnerability; Figure II-4). Theabsorbing capacity of a building for mechanical energy (forces)may be increased by using building materials and methods that canwithstand the shaking created by an earthquake of a particularmagnitude. However, the absorbing capacity of any one structurecontributes a very small amount to the total absorbing capacity ofthe community-at-risk for the earthquake. The total absorbingcapacity of the structures (buildings and people) consists of theaggregate of the absorbing capacities of all of the living andnon-living structures in the area-at-risk. The structures mostvulnerable to damage will be those with the highest risk forStructural Damage. In the photograph in Figure II-4, the mosquehad a much higher absorbing capacity for the forces of theearthquake and tsunami than did the surrounding residences. Thisdoes not mean that only those structures with the greatestvulnerability (ie, highest risk for damage) will be damagedstructurally, as the amount and type of damage sustained also aredetermined by the type of energy of the event as well as othercharacteristics of the event.

It is important to note that each structure has a differentabsorbing capacity and its own specific relationship between theamount and type of damage and the amount and nature of the


Figure II-4. Photograph of Structural Damages Resultingfrom the Tsunami of 2004. The tower that remains standinghad a much greater absorbing capacity than did thesurrounding structures.


Figure II-5. Illustration of Hypothetical Relationshipsbetween the Amount of Damage from an Event andDifferent Levels of Absorbing Capacity. The higher theabsorbing capacity, the less the amount of structural damagethat will be sustained.





changes in the amount of kinetic energy released by the event.Differences in the absorbing capacities relate directly to differencesin damage sustained from similar events. One community may beable to withstand an earthquake of a given magnitude withoutsustaining any Structural Damage, while an event of the same typeand magnitude may produce profound destruction in anothercommunity in which the structures have a lower absorbing capacity.While the Seattle (Washington, USA; 2001) and Northridge(California, USA; 1994) earthquakes were of “equal” magnitudes,the Structural Damage sustained in the Seattle area was substantiallyless than that sustained from the Northridge earthquake. Althoughthe magnitude of the shaking, as estimated using the ModifiedMercali scale, was less in Northridge than in Seattle, the duration ofboth events was similar, and the characteristics of the events did notdiffer in terms of themagnitude of the energy released. Similarly, theamounts and severity of damage sustained following the 2010earthquakes in Haiti and Chile differed substantially, although themagnitude of the earthquake in Chile was more than 500 foldgreater than the earthquake in Haiti.39 These differences likely weredue to the different absorbing capacities for these similar events.Only through multi-factorial analyses can differences in theabsorbing capacities be implicated.

Capacity-building efforts can be prioritized to increase theabsorbing capacity of those structures that support the essentialfunctions of the community (provision of adequate amounts ofgoods, services, and other resources). For example, efforts may bedirected at enhancing the absorbing capacity of the health facilitiesin the community so that they will sustain little or no StructuralDamage and be able to continue to function during or following anevent. Building new hospitals and retrofitting existing hospitalswith augmented absorbing capacity for events for which theyare at-risk was a major goal of the “Safe Hospitals” initiativesof the Pan-American Health Organization (Washington, DCUSA) and UN-ISDR (2009-2010).40 In areas prone to flooding,capacity-building efforts may focus on flood prevention byre-forestation, building levees, and relocating dykes. Thus, whenan event (rainfall) does occur, potential Structural Damage can beprevented or minimized.

Structural Damage may occur not only to the infrastructure, butalso to the people, equipment, and supplies (goods, services, andresources) that are essential for the ongoing functions of thecommunity. Thus, continuity of the functions of the affectedcommunity may be compromised not only by Structural Damageto the infrastructure, but also by damage to humans (ie, health careworkers), equipment, and/or supplies.

Lastly, Structural Damage also may be indirect—not related tothe energy of the event. Damage may be the result of injuries fromother structures damaged from the energy of the event. Forexample, injuries may result from damaged structures, such aslacerations from debris during cleanup, or from other indirectcauses, such as myocardial infarction, tetanus, and suicideattempts.

Structural Damage to Humans—Humans are highly vulnerable(ie, have low absorbing capacity) to transfers of kinetic energyreleased from a hazard during an event, regardless of the type ofenergy involved (mechanical (physical force), electrical, thermal,chemical, nuclear, or biological). Damage to humans is calledinjury. The nature of the injuries created by the transfer of theenergy is dependent upon the type of energy and the location ofthe transfer. Mechanical energy manifests as forces that maydisrupt the structure of the body area impacted (trauma).

Generally, injuries (Structural Damages), per se, are not a directcause of death: injuries result in death from losses of functionsrelated to the Structural Damage sustained from the transfer ofenergy onto or into the body. Loss of vital functions due to theinjuries results in death. Electrical energy may cause the heart tofibrillate, which results in rapid death due to failure of the heart topropel blood. Asphyxia due to loss of a patent airway required forventilation or external compression of the thorax or abdomen(traumatic asphyxia) may result in sudden death. Basically, eventsdo not cause deaths, losses of organ systems functions due toinjuries cause death. Rather than reporting the numbers of deathsas damage, it is cogent to report the number, types, and severity ofinjuries sustained and the number and causes of deaths related tothe injuries. It is important to know the number and proportion ofinjured who succumbed (ie, to determine which deaths potentiallywere preventable). Knowing only the numbers of deaths is of littlevalue.35 In order to identify preventable deaths, it is important tounderstand the mechanisms of injury and the causes of death.Thus, it is essential that the mechanisms of injury be documented.

However, humans can take actions to increase their protectionfrom the kinetic energy of an event. During an earthquake, theycan position themselves in doorways or underneath sturdystructures that, in turn, have a higher absorbing capacity thandoes their body. Thus, much of the energy that could createdamage to their body is absorbed by another structure with lessvulnerability to the kinetic energy of the event. Humans also canaugment their protection through the use of accessories that have ahigher absorbing capacity than does their body. The donning ofbulletproof vests, flak jackets, helmets, and personal protectiveequipment, as well as the use of seat restraints and installation ofdeployable airbags in motor vehicles, are examples of augmentingpersonal absorbing capacity; all these accessories absorb and/ordistribute the kinetic energy of the event before it transfers to thebody. Immunizations represent another method of increasinghumans’ absorbing capacity for a specific organism; they do notprevent the organisms from entry into the body, but they mayprevent the Structural Damage (the disease) that can result fromexposure to the organisms. Additional examples include donningfire-resistant or insulated clothing, shielding from radiation, usingpersonal protective equipment, neutralization of chemicals,treatment with antibiotics, removal or containment of the hazard,and evacuation to prevent exposure.

It also must be noted that humans also are highly vulnerable tolosses of goods, services, and resources upon which they aredependent. Inadequate supplies of potable water rapidly result indehydration and lack of food results in starvation.

Assessments of Structural Damage—The amount and type ofStructural Damage to the infrastructure and the environmentgenerally is determined visually. However, on some occasions, andin some settings, Structural Damage may be detected fromassessments of levels of function. For example, damage to watersupply lines may be detected by the failure to obtain water from atap; failure of electrical energy may be detected by losses ofelectrical lighting; damage to roads/bridges may be detected by theinability to receive essential medical supplies. All assessments ofStructural Damage (infrastructure, environment, living beings,and losses of goods, services, and/or resources) must bedocumented. The study of events that do not result in a disastermay be as important as those focusing only on disasters. Why dotwo events of similar energy types and magnitudes cause a disasterin one setting and not in another?





Functional Damage (Loss of Function(s); Figure II-2 andFigure II-3)—A community provides services (functions) to itspopulation. A community operates by functions. A function is amode of action or activity by which a thing fulfills its purpose;41

the purpose for which something is designed or exists.42 Goods arenot functions. A good is a desirable object.43 The functions of allSystems depend on the functional integrity of the structure(s) thatsupport them. For example, in a cell, the glucose and oxygenimported into the cell must be transformed into energy byprocesses within the cellular mitochondria. The energy producedthen is used to fuel processes required for cellular functions.Similarly, available goods and services must be transformedinto functions by the Systems that comprise a community(Figure II-6). All operational functions of a community are pro-duction functions (ie, transformation processes that convert goodsand services (resources/costs) into the operational functions (out-puts) that serve the community). The transformation process usedis unique for every function. The transformation from goods andservices into functions requires an accessible supply of goods andservices and an intact production process; the production processconsumes resources. The consumable resources consist of theavailable goods and the services and other costs (eg, opportunityand financial). The resources consumed by the transformationprocess are the costs of the process of producing the functions fromthe available goods and services.

This transformation process requires human input and an intactinfrastructure. The production function requires an infrastructureand includes the physical space (infrastructure), supplies,equipment, and knowledgeable personnel: damage to the infra-structure (space and equipment) may impair the production offunctions regardless of the expendable resources available. Theessential functions that comprise a community are organized intosystems that are called the Societal Systems.12

Compromised levels of function may result not only fromdecreases in available goods, services, and other resources, but toinadequate transformation due to loss of infrastructure (spaceand equipment) and/or personnel that have been injured or areunable to respond. Structural Damage(s) caused by an event may

involve goods, services, and other resources, and/or the infra-structure utilized by the transformation process may result ininadequate supplies of the goods, services, and resources requiredby the transformation process. The supply of available resourcesmay be compromised due to direct damage, and/or loss of goodsand services, and/or by inaccessibility to the needed suppliesof goods and services and/or to lack of financial resources.Compromised supplies of available resources caused by an eventmay or may not impair the operation of the Systems (ie, causeFunctional Damage) of the community or persons impacted bythe event.

Just as not all events necessarily result in Structural Damage, notall Structural Damage necessarily diminishes the levels of function ofone or more of the Societal Systems; the levels of function of somefunctions may become compromised while others may not.1(pp51) Inaddition to direct damage to infrastructure or living beings, indirectdamages may cause diminished/losses of levels of function from aloss of resources (supplies, personnel, and equipment) and/orfailures in the transformation process. For example, damage to awater delivery pipe may result in loss of water (Functional Damage/loss of function delivery) to a specific site, but water may be obtainedfrom other sources, thereby buffering the loss of function thatresulted from the Structural Damage. Interrupted electricaltransmission lines may result in diminished levels of functions ofmany functions that rely on electricity. However, some of thesefunctions may be maintained through the use of alternate power(energy) sources such as electrical generators that transform fuel intoelectricity. Damage to an operating suite may impair the provision ofsurgical services even with adequate supplies of available goods andservices. Relief interventions may be directed to providing thefunctions lost or overwhelmed due to Structural Damage. During adisaster, outside assistance is required to fill-in existing gaps in someessential functions.

Buffering Capacity—The buffering capacity is the ability of acommunity, or components of a community, to cope with theStructural Damage or Functional Damage sustained from an eventwithout a decrease or loss of function of the System (ie, continue tofunction in spite of the Structural Damage; Figure II-3 andFigure II-7).1(pp82-86) The likelihood that the Structural Damagecaused by an event will result in a change in the functional state ofone or more Systems of a community is related to: (1) thestructures damaged; (2) the extent of the damage; (3) the role ofthe damaged structures in the function(s) of the community;and (4) the buffering capacity of the component Systems of thecommunity. The greater the buffering capacity of the community,the greater the likelihood that the community and its functionalSystems will continue to perform despite the Structural Damagessustained.

As with absorbing capacity, the buffering capacity can be altered(attenuated or augmented) by human actions, or by damage from aprevious event. For example, damage to the electrical powersystem required to sustain the functions of a hospital can bebuffered by the use of electrical generators powered by anothersource of fuel. Using backup generator electricity allows thecontinued operations (functions) of those services that aredependent upon electricity (eg, blood storage, mechanicalventilators, operating suite equipment, light, and heat). Similarly,establishing alternative care sites can allow a health care facility tocontinue to function despite damage sustained to a part of itsstructure. Increasing the buffering capacity can minimize orprevent Functional Damage (loss of function(s)) and thus, is part


Figure II-6. Production Functions Illustrating theRelationships Between Levels of Function and AvailableGoods and Services. Following an event, changes in levels offunction(s) must be transformed into goods and servicesneeded to restore levels of function (A). As needs are met,goods and services must be transformed into functions (B).





of capacity building and contributes to the overall resilience of thecommunity for an event (Figure II-3).

Theoretically, if the buffering capacity of a community or acomponent of the community is adequate, no changes in thefunctions of that System will occur if Structural Damage issustained. For example, damage to a bridge to an island maycompromise the transportation of people and goods to the island.However, if transportation to the island can be provided using aferry system, the function may be maintained: the ferry systemprovides the buffering capacity for the Logistics and Transporta-tion System. Whenever the changed supplies of essential goodsand/or services secondary to Structural Damage cannot supportthe essential functions of a Societal System, the level offunctioning of that System will become compromised—thebuffering capacity for that function has been exceeded (Figure II-7).As long as the supplies of essential goods and/or services remain ator above their functional threshold for the Societal System, levelsof essential functions continue (Figure II-7). In some instances,luxury functions1(pp118-122) (if any exist) may be compromised,causing some discomfort/inconvenience for the affected society,but the essential functions will be preserved. In the example of theferry, it may take longer and be less convenient to reach the island,but function is preserved. Likewise, damage to part of a hospitalmay require that non-essential cosmetic surgeries be discontinuedin order that the operating units can be used for the treatment ofthe injured. In both examples, sustained damage did result in alimitation of some functions, but not in the provision of essentialfunctions (Figure II-7). It is important to note that every System/Subsystem has different buffering capacity for the Structural and/or Functional Damages sustained.

Structural Damage may compromise the available supplies ofgoods and/or services and may result in the level of function ofsome of the components of the affected community to fall belowthe critical levels of function required to maintain its normative

crude mortality rate (CMR)—the goods and/or services availableare below their respective critical threshold and the CMR of theaffected population increases. Depending on the amount and typeof Structural Damage sustained, some functions of the Systemmay be able to continue unabated, while the functioning level ofother components may fall below their critical levels of function.For example, the injury/death of medical laboratory personnel maycompromise the ability to obtain laboratory studies or to type andcross-match blood essential for the survival of some of the victims.This may result in the inability to successfully resuscitate victimswith traumatic injuries, or to perform needed surgery, and thus,result in increases of the CMR. Damage to those components of acommunity that normally operate at just above their critical levelsof function have little buffering capacity for any losses of goodsand/or services required to sustain the function, and the CMR willincrease due to loss(es) of their minimal critical infrastructure(Figure II-7).1(pp118-122)

Levels of Function—The level(s) of function(s) (functionalstatus) of any Societal System prior to the onset of an event servesas the functional baseline for the System being considered(pre-event level of functions). Within each System, four levelsof function have special relevance: (1) Essential; (2) Conditional;(3) Critical; and (4) Luxury. Essential levels of function for aSystem define the levels of function required to maintain the basicservices to the community. Conditional functional levels are levelsrequired due to increased demands for services related to increasedburdens produced by the Structural Damage.1(p115) Critical levelsof functions are the levels of functioning below which the CMR ofthe affected population increases. Not all Societal Systems or theircomponent subfunctions have a critical level of function. Luxurylevels of functions are those levels of function that are not neededfor the community to provide essential services to the population.

A threshold is a boundary beyond which a radically differentstate of affairs (or function) exists.44 A functional threshold definesthe minimum level of goods and services at which all the essentialaspects of the System's functions are operational; it is the minimumlevel of available goods, services, and resources required to providethe essential services to the community (Figure II-7).1(p74)

Either at or above the functional threshold of a System(or component of a System), the System can provide all of theessential functions of the community. Systems that are operatingbelow their respective essential levels of function require prioritiza-tion of the essential functions that must be continued and those thatcan be suspended.

The relationships between the available goods and services tolevels of function are illustrated in Figure II-7. With an intactinfrastructure, adequate essential personnel, and an intact transfor-mation process, levels of function are dependent upon the suppliesof goods and services available. At the baseline (pre-event) levels ofavailable goods and services, the level of functioning of a System areindicated by the dashed line (pre-event). As the quantities/qualitiesof resources become compromised, the level of function decreases.If the community enjoys luxury functions, the available levels ofluxury functions decline. As the quantity of goods and servicesdeclines further, eventually the levels of function falls below thatrequired to sustain the essential functions required by thecommunity (functional threshold). If the amount of available goodsand services declines to point X on the axis, the respective levels offunctions fall further. The level of function of a System (or acomponent of the System) with a high buffering capacity (A)remains at a higher level than does the level of functioning of the


Figure II-7. Relationship between Supplies of Goods andServices and Levels of Function. As available goods andservices decline, the functions of a System drop below itsfunctional threshold. Further declines may cause functions todrop to its critical level of function.Abbreviation: CMR, crude mortality rate.





System (or its component) with a low buffering capacity (B) for thatfunction. If the System or any its components has a critical level offunction below which the CMR increases, further compromise ofavailable goods and services to supplies below the critical thresholdresults in an increase in the CMR. The shape and position of thecurve describing the relationship between available goods andservices and levels of functioning of a given System varies with thespecific community.

In general, deficits in function (functional deficits) are correctedby restoring the functional integrity of the damaged structures orby providing a sufficient supply of goods and services. Thus, whenpossible, Structural Damage is repaired or the damaged structuresare replaced, and deficits in accessible supplies are corrected usingreplacement supplies, gaining access to the “needed” supplies,and/or providing substitute or additional personnel.

The critical threshold is the minimum level of available goodsand services required to maintain the normative CMR of thecommunity. For example, if goods, services, and/or resourcescannot support the essential functions of a Societal System, thelevel of functioning of that System will become compromised—the buffering capacity for that function has been exceeded(Figure II-7). As long as the supplies of essential goods and/orservices remain at or above their functional threshold for theSocietal System, levels of essential functions continue(Figure II-7) provided that the production process is intact. Insome instances, luxury functions1(pp118-122) (if any exist) may becompromised, causing some discomfort/inconvenience for theaffected community, but the essential functions will be preserved.In the example of backup generators, the generators may provideonly enough power to keep the vital activities in a hospitaloperational. Other functions may be sacrificed due to a lack ofsufficient electrical power. Likewise, damage to part of a hospitalmay require that non-essential cosmetic surgeries be discontinuedin order that the surgical suites can be used for the treatment of theinjured. In both examples, the damage sustained resulted in alimitation of some functions, but not in the provision of essentialfunctions (Figure II-7). It is important to note that every Systemand its subsystems, and their functional units, have a different,unique buffering capacity for the Structural Damage sustained. Itmust be noted that compromises in the levels of function and/orgoods and services and resources of other Systems may impair thelevels of function of the System(s) being studied.

Compromise in the availability of supplies of goods and/orservices and may result in a decline in the level of function of someof the components of the affected community to the critical levels offunction required to maintain the normative CMR (ie, the quality/quantity of the goods and/or services available are below theirrespective critical threshold and theCMRof the affected populationincreases). Depending on the amount and type of StructuralDamage sustained, some functions of the System may be able tocontinue unabated, while the functioning level of other componentsmay fall below their respective critical levels of function. Forexample, the injury/death of medical laboratory personnel maycompromise the ability to obtain laboratory tests or to type andcross-match blood essential for the survival of some of the victims.This may result in the inability to successfully resuscitate victimswith traumatic injuries or perform needed surgery, and thus, resultin increases of the CMR. Damage to those components of acommunity that normally operate at just above their critical levels offunction have little buffering capacity for any losses of goods and/orservices and/or infrastructure required to sustain the function, and

the CMR will increase due to loss(es) of their minimal criticalinfrastructure (Figure II-7).1(pp118-122) Again, it is stressed thatFunctional Damages in Systems outside of the System beingstudied may produce needs in the System being studied.

Assessments of Function—Alterations in functional states aredetected by assessments of the levels of functions. However, thecompromise of function(s) of some Systems may be implied fromobserved Structural Damage. Conversely, the impact of damagedor inaccessible essential resources may be detected by a decline inthe functional status of a particular System. For example, theinability of a hospital to provide health care services may be due toinjured personnel, damaged equipment, or loss of electrical power.

The value of assessments of the functional status of a System aredependent upon the indicators of function being used.1(p51,82-86),45

The same indicators of function must be used for defining the:(1) pre-event functional levels; (2) the disturbances of function thatresult from the Structural Damage; and (3) the changes in functionrelated to interventions. Care must be exercised in selectingindicators of function so that they have the construct validity andthat they repeatedly can be used to adequately assess changes in thelevels of function.

The disturbances in the functions of a community/society as awhole, or in any of the Systems that comprise the affectedcommunity, always are judged against the functional status of thecommunity or its Systems before the precipitating event began(pre-event status). This requires an inventory of functionsprovided by a community and/or its components. Preferably, thisinventory will be linked to the structures that support thefunctions. This linkage will facilitate the prediction of FunctionalDamage associated with Structural Damage. In a hospital, itshould be possible to predict what will happen to its functions if aparticular area of the hospital is damaged or destroyed. Thisrelationship is important for guiding risk-reduction as well as reliefor recovery interventions.

Needs (Figure II-2 and Figure II-3)—When a System operatesbelow its essential level of function, its compromised functioncreates needs. Decrements of levels of function (FunctionalDamage) are not deficits in available goods and/or services; rather,changes in function produce needs, and the needs are the goodsand services required to prevent further deterioration of function(Relief Responses or damage control), fill the gaps in essentialfunctions (Relief Responses), or restore function(s) to the pre-event level (Recovery Responses). Needs are determined throughthe synthesis of the data/information obtained from assessmentsand other sources. The determination of needs from the assess-ments involves transforming the assessed changes in functions intothe goods and services required to repair the functional deficits.The process for converting Functional Damage into needs mayincorporate several assumptions.46

Functional needs are the needs generated when the quantity/quality of available supplies of goods and services falls below theirrespective functional threshold, or the infrastructure and processesrequired for the conversion are damaged or rendered dysfunctional,and the functional state of a System (or any or all of its components)becomes compromised. The existing levels of function cannotmeet all of the gaps in function of one or more Societal Systems.

Critical needs occur when the level of functioning falls below thecritical levels of function and require prompt responses to preventthe CMR from increasing further. Conditional (situational) needsare needs created by increased demand for goods and services rather





than diminished function.1(p51) The increased burdens caused bythe surge of injured/ill persons as a result of an event, or by theneeds for increased surveillance in order to detect and manageoutbreaks of diseases, are examples of conditional needs.

Luxury functions are conveniences for the impacted communityand are not required for the provision of essential services.Therefore, compromised luxury functions do not produce needs.Needs are different from the wants and demands of the affectedpopulation. The perceptions of needs by the affected populationtend to differ from those of the responders. In general, thepopulation perceives their needs to be greater than their real needs,while responders tend to perceive the affected population’s needsto be less than their actual needs.47

Responses (Figure II-2 and Figure II-3)—Responses areinterventions;48,49 actions undertaken to meet the relief or recoveryneeds that resulted from an event. As noted above, needs areexpressed as the goods and services and resources required to sustainthe levels of function (relief) or to contribute to recovery. Theobjective of each response must be related to a specific identifiedneed or set of needs (Figure II-2 and Figure II-3). Additionally,every response (intervention) must have a stated overarching goal aswell as objectives that contribute to attaining that goal to which theresponse is contributing.Within the context of the defined goal, themost appropriate, and hopefully the most efficient intervention isselected, providers are identified, and the intervention is imple-mented according to anOperational Plan.46,50 In general, responsesare directed either to correcting the functional damage, supple-menting levels of function, and/or repairing/replacing the damagedstructure, which, in turn, will increase the level of function, andthus, decrease the needs, or increase the capacities of the commu-nity to cope with or respond to an event.

Responses to needs consist of three categories: (1) Ordinary;(2) Extra-ordinary; and (3) Outside. Ordinary responses comprisethe routine, day-to-day responses to needs that do not require use ofreserve goods, services, and other resources; examples include day-to-day interventions by Emergency Medical Services, emergencydepartment services, elective and routine surgeries, routine lawenforcement, clinic visits, and equipment maintenance. When theneeds cannot be met by ordinary responses, extra-ordinaryresponses are recruited. Extraordinary responses include theaddition of backup equipment, supplemental supplies and person-nel, augmented services, andmore, all of which normally are kept inreserve for special circumstances.When the needs cannot be met byordinary responses and extra-ordinary responses are required, an“emergency” exists for the area affected. Both ordinary and extra-ordinary responses use local resources. Extra-ordinary responsesutilize the community’s Local Response Capacity. No resourcesfrom outside of the area directly affected are required to meet thedefined need(s). Responses to defined needs that cannot be metusing ordinary and extra-ordinary resources require assistance fromoutside the area directly affected. When these needs cannot be metusing local resources, assistance from outside of the affected area isrequired to help fill-in the gaps in essential functions; availableoutside assistance/responses are required until the local communitycan manage/restore the levels of functions of essential serviceswithout the outside help. When needs cannot be met by localresources, a disaster exists for that function.

Response Capacities—The response capacity is the abilityto respond or intervene to meet needs and prevent furtherdeterioration of function(s) of a community or components of a

community impacted by an event (Figure II-3). Response capacityoften is referred to as “preparedness.” Such responses requiregoods, services, and/or other resources that are contained in theLocal Response Capacity; the Local Response Capacity is theability of the systems within the impacted area to meet the needs ofthe impacted population. The Local Response Capacity has twocomponents: (1) Ordinary; and (2) Extra-ordinary (reserve). Eachcommunity has a capacity to respond to day-to-day (ordinary)needs of the population without having to mobilize reserve goodsand services. Needs that require resources that are in excess ofthose used for the provision of daily functions are extra-ordinary,and these reserves also are part of the Local Response Capacity.The Local Response Capacity includes Response Plans, compe-tent individuals/organizations, available equipment, supplies, andother plans (often referred to as “contingency plans”) to supportthe responses/interventions selected to meet the needs. Whenreserve supplies are used, the situation is an “Emergency” for thecomponents required.When the needs cannot be met by use of thelocal response capacity, outside response capacities are required.

Outside Response Capacity (Figure II-3) consists of the ability ofsystem(s) outside of the area directly impacted by an event torespond or intervene to help meet the needs of an impactedpopulation. Thus, response capacities and capabilities increase asone proceeds up the hierarchy of government: an individual’sresponse capacity is less than that of the neighborhood, which is lessthan that of the community, which is less than that of the state/province, which is less than that of the national government, whichis less than the capacities of the international community. Thus, asresponses move up the hierarchy, more and more resources can bebrought to assist the affected community in meeting its needs. Anyresponse capacity from higher in the hierarchical level than thecommunity affected by the event is considered to be part of theOutside Response Capacity. Both the Local and Outside ResponseCapacities can be augmented by human actions.46,51

Emergency (Figure II-2 and Figure II-3)—When the community(or its component Systems) use the reserve goods, services, andother resources within its Local Response Capacity to meet theneeds that result from the changes in functions (FunctionalDamage) of one or more of its components, the situation is an“Emergency” for that community or the System; in other words,the Local Response Capacity is sufficient to meet the needs of theaffected community or the part(s) of the community that is(are)compromised, and no outside assistance (use of the OutsideResponse Capacity) is required. For example, if the community’sEmergency Medical Services and medical facilities are able toprovide all of the medical care required from an event that resultedin multiple casualties, no Outside Response Capacity for thatcomponent of the community is required, and the situation is anemergency for the Systems affected.

Disaster (Figure II-2 and Figure II-3)—A Disaster occurs whenuse of the Local Response Capacity of the community and/or itscomponents is insufficient to meet the needs created by the lossesof functions and/or the inability to meet the conditional needs.Therefore, in a disaster, outside assistance is required to meet atleast part of its needs (including conditional/situational needs).The definition of disaster inherently includes scale; what con-stitutes a disaster for a province or state may not represent adisaster for a nation. Generally, as responses move up in the





government hierarchy, the amount of available resources increases.In some small countries, the only entity above the communitygovernment may be that of the nation.

A disaster could occur in one Societal System of the affectedcommunity and not in another, depending on the respectiveResponse Capacities of the Systems. For example, the terroristattack in New York City (New York, USA) in

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Research and Evaluations of the Health Aspects of ... · Chief, Prehospital and Disaster Medicine 2. Nursing Section Editor, Prehospital and Disaster Medicine; Executive Secretary,