Basic terms of disaster risk reduction
|The ISDR Secretariat
presents these basic definitions on disaster risk reduction in order
to promote a common understanding on this subject, for use by the
public, authorities and practitioners. The terms are based on a broad
consideration of different international sources. This is a continuing
effort to be reflected in future reviews, responding to a need expressed
in several international venues, regional discussions and national
commentary. Feedback from specialists and other practitioners to
improve these definitions will be most welcome.
level of loss a society or community considers acceptable given
existing social, economic, political, cultural, technical and
In engineering terms, acceptable
risk is also used to assess structural and
non-structural measures undertaken to reduce
possible damage at a level which does not harm
people and property, according to codes or "accepted
practice" based, among other issues, on
a known probability of hazard.
of organic origin or those conveyed by biological vectors,
including exposure to pathogenic micro-organisms, toxins and
bioactive substances, which may cause the loss of life or injury,
property damage, social and economic disruption or environmental
Examples of biological hazards:
outbreaks of epidemic diseases, plant or animal
contagion, insect plagues and extensive infestations.
and regulations controlling the design, construction, materials,
alteration and occupancy of any structure to insure human safety
and welfare. Building codes include both technical and functional
of all the strengths and resources available within a community,
society or organization that can reduce the level of risk,
or the effects of a disaster.
Capacity may include physical,
institutional, social or economic means as
well as skilled personal or collective attributes
such as leadership and management. Capacity
may also be described as capability.
aimed to develop human skills or societal infrastructures within
a community or organization needed to reduce the level of risk.
In extended understanding,
capacity building also includes development
of institutional, financial, political and
other resources, such as technology at different
levels and sectors of the society.
of a place or region is changed if over an extended period
(typically decades or longer) there is a statistically significant
change in measurements of either the mean state or variability
of the climate for that place or region.
Changes in climate may be due
to natural processes or to persistent anthropogenic
changes in atmosphere or in land use. Note
that the definition of climate change used
in the United Nations Framework Convention
on Climate Change is more restricted, as it
includes only those changes which are attributable
directly or indirectly to human activity.
by which people or organizations use available resources and
abilities to face adverse consequences that could lead to a
In general, this involves managing
resources, both in normal times as well as
during crises or adverse conditions. The strengthening
of coping capacities usually builds resilience
to withstand the effects of natural and human-induced
taken to counter and reduce disaster risk. They most commonly
refer to engineering (structural) measures but can also include
non-structural measures and tools designed and employed to
avoid or limit the adverse impact of natural hazards and related
environmental and technological disasters.
disruption of the functioning of a community or a society causing
widespread human, material, economic or environmental losses
which exceed the ability of the affected community or society
to cope using its own resources.
A disaster is a function of
the risk process. It results from the combination
of hazards, conditions of vulnerability and
insufficient capacity or measures to reduce
the potential negative consequences of risk.
process of using administrative decisions, organization, operational
skills and capacities to implement policies, strategies and
coping capacities of the society and communities to lessen
the impacts of natural hazards and related environmental and
technological disasters. This comprises all forms of activities,
including structural and non-structural measures to avoid (prevention)
or to limit (mitigation and preparedness) adverse effects of
risk reduction (disaster reduction)
framework of elements considered with the possibilities to
minimize vulnerabilities and disaster risks throughout a society,
to avoid (prevention) or to limit (mitigation and preparedness)
the adverse impacts of hazards, within the broad context of
The disaster risk reduction
framework is composed of the following fields
of action, as described in ISDR's publication
2002 "Living with Risk: a global review
of disaster reduction initiatives", page
awareness and assessment including hazard
analysis and vulnerability/capacity analysis;
development including education, training,
research and information;
commitment and institutional frameworks,
including organisational, policy, legislation
and community action;
of measures including environmental management,
land-use and urban planning, protection of
critical facilities, application of science
and technology, partnership and networking,
and financial instruments;
warning systems including forecasting, dissemination
of warnings, preparedness measures and reaction
of timely and effective information, through identified institutions,
that allows individuals exposed to a hazard to take action
to avoid or reduce their risk and prepare for effective response.
Early warning systems include
a chain of concerns, namely: understanding
and mapping the hazard; monitoring and forecasting
impending events; processing and disseminating
understandable warnings to political authorities
and the population, and undertaking appropriate
and timely actions in response to the warnings.
set of relationships of living organisms functioning as a unit
and interacting with their physical environment.
The boundaries of what could
be called an ecosystem are somewhat arbitrary,
depending on the focus of interest or study.
Thus the extent of an ecosystem may range from
very small spatial scales to, ultimately, the
entire Earth (IPCC, 2001).
Niño-southern oscillation (ENSO)
interaction of the tropical Pacific Ocean and the global atmosphere
that results in irregularly occurring episodes of changed ocean
and weather patterns in many parts of the world, often with
significant impacts, such as altered marine habitats, rainfall
changes, floods, droughts, and changes in storm patterns.
The El Niño part of
ENSO refers to the well-above-average ocean
temperatures along the coasts of Ecuador, Peru
and northern Chile and across the eastern equatorial
Pacific Ocean, while the Southern Oscillation
refers to the associated global patterns of
changed atmospheric pressure and rainfall.
La Niña is approximately the opposite
condition to El Niño. Each El Niño
or La Niña episode usually lasts for
and management of resources and responsibilities for dealing
with all aspects of emergencies, in particularly preparedness,
response and rehabilitation.
Emergency management involves
plans, structures and arrangements established
to engage the normal endeavours of government,
voluntary and private agencies in a comprehensive
and coordinated way to respond to the whole
spectrum of emergency needs. This is also known
as disaster management.
impact assessment (EIA)
undertaken in order to assess the effect on a specified environment
of the introduction of any new factor, which may upset the
current ecological balance.
EIA is a policy making tool
that serves to provide evidence and analysis
of environmental impacts of activities from
conception to decision-making. It is utilised
extensively in national programming and for
international development assistance projects.
An EIA must include a detailed risk assessment
and provide alternatives solutions or options.
of the capacity of the environment to meet social and ecological
objectives, and needs.
Potential effects are varied
and may contribute to an increase in vulnerability
and the frequency and intensity of natural
Some examples: land degradation,
deforestation, desertification, wildland fires,
loss of biodiversity, land, water and air pollution,
climate change, sea level rise and ozone depletion.
statement or statistical estimate of the occurrence of a future
event (UNESCO, WMO).
This term is used with different
meanings in different disciplines.
earth processes or phenomena that may cause the loss of life
or injury, property damage, social and economic disruption
or environmental degradation.
Geological hazard includes
internal earth processes or tectonic origin,
such as earthquakes, geological fault activity,
tsunamis, volcanic activity and emissions as
well as external processes such as mass movements:
landslides, rockslides, rock falls or avalanches,
surfaces collapses, expansive soils and debris
or mud flows.
Geological hazards can be single,
sequential or combined in their origin and
information systems (GIS)
that combine relational databases with spatial interpretation
and outputs often in form of maps. A more elaborate definition
is that of computer programmes for capturing, storing, checking,
integrating, analysing and displaying data about the earth
that is spatially referenced.
Geographical information systems
are increasingly being utilised for hazard
and vulnerability mapping and analysis, as
well as for the application of disaster risk
||A gas, such
as water vapour, carbon dioxide, methane, chlorofluorocarbons
(CFCs) and hydrochlorofluorocarbons (HCFCs), that absorbs and
re-emits infrared radiation, warming the earth's surface and
contributing to climate change (UNEP, 1998).
damaging physical event, phenomenon or human activity that
may cause the loss of life or injury, property damage, social
and economic disruption or environmental degradation.
Hazards can include latent
conditions that may represent future threats
and can have different origins: natural (geological,
hydrometeorological and biological) or induced
by human processes (environmental degradation
and technological hazards). Hazards can be
single, sequential or combined in their origin
and effects. Each hazard is characterised by
its location, intensity, frequency and probability.
studies and monitoring of any hazard to determine its potential,
origin, characteristics and behaviour.
processes or phenomena of atmospheric, hydrological or oceanographic
nature, which may cause the loss of life or injury, property
damage, social and economic disruption or environmental degradation.
include: floods, debris and mud floods; tropical
cyclones, storm surges, thunder/hailstorms,
rain and wind storms, blizzards and other severe
storms; drought, desertification, wildland
fires, temperature extremes, sand or dust storms;
permafrost and snow or ice avalanches. Hydrometeorological
hazards can be single, sequential or combined
in their origin and effects.
physical and socio-economic planning that determines the means
and assesses the values or limitations of various options in
which land is to be utilized, with the corresponding effects
on different segments of the population or interests of a community
taken into account in resulting decisions.
Land-use planning involves
studies and mapping, analysis of environmental
and hazard data, formulation of alternative
land-use decisions and design of a long-range
plan for different geographical and administrative
Land-use planning can help
to mitigate disasters and reduce risks by discouraging
high-density settlements and construction of
key installations in hazard-prone areas, control
of population density and expansion, and in
the siting of service routes for transport,
power, water, sewage and other critical facilities.
and non-structural measures undertaken to limit the adverse
impact of natural hazards, environmental degradation and technological
processes or phenomena occurring in the biosphere that may
constitute a damaging event.
Natural hazards can be classified
by origin namely: geological, hydrometeorological
or biological. Hazardous events can vary in
magnitude or intensity, frequency, duration,
area of extent, speed of onset, spatial dispersion
and temporal spacing.
and measures taken in advance to ensure effective response
to the impact of hazards, including the issuance of timely
and effective early warnings and the temporary evacuation
of people and property from threatened locations.
to provide outright avoidance of the adverse impact of hazards
and means to minimize related environmental, technological
and biological disasters.
Depending on social and technical
feasibility and cost/benefit considerations,
investing in preventive measures is justified
in areas frequently affected by disasters.
In the context of public awareness and education,
related to disaster risk reduction changing
attitudes and behaviour contribute to promoting
a "culture of prevention".
of informing the general population, increasing levels of consciousness
about risks and how people can act to reduce their exposure
to hazards. This is particularly important for public officials
in fulfilling their responsibilities to save lives and property
in the event of a disaster.
Public awareness activities
foster changes in behaviour leading towards
a culture of risk reduction. This involves
public information, dissemination, education,
radio or television broadcasts, use of printed
media, as well as, the establishment of information
centres and networks and community and participation
facts and knowledge provided or learned as a result of research
or study, available to be disseminated to the public.
and actions taken after a disaster with a view to restoring
or improving the pre-disaster living conditions of the stricken
community, while encouraging and facilitating necessary adjustments
to reduce disaster risk.
Recovery (rehabilitation and
reconstruction) affords an opportunity to develop
and apply disaster risk reduction measures.
of assistance or intervention during or immediately after a
disaster to meet the life preservation and basic subsistence
needs of those people affected. It can be of an immediate,
short-term, or protracted duration.
of a system, community or society potentially exposed to hazards
to adapt, by resisting or changing in order to reach and maintain
an acceptable level of functioning and structure. This is determined
by the degree to which the social system is capable of organizing
itself to increase its capacity for learning from past disasters
for better future protection and to improve risk reduction
of structures to become more resistant and resilient to the
forces of natural hazards.
Retrofitting involves consideration
of changes in the mass, stiffness, damping,
load path and ductility of materials, as well
as radical changes such as the introduction
of energy absorbing dampers and base isolation
systems. Examples of retrofitting includes
the consideration of wind loading to strengthen
and minimize the wind force, or in earthquake
prone areas, the strengthening of structures.
of harmful consequences, or expected losses (deaths, injuries,
property, livelihoods, economic activity disrupted or environment
damaged) resulting from interactions between natural or human-induced
hazards and vulnerable conditions.
Conventionally risk is expressed
by the notation
Risk = Hazards x Vulnerability. Some disciplines also include the
concept of exposure to refer particularly to the physical aspects
Beyond expressing a possibility
of physical harm, it is crucial to recognize
that risks are inherent or can be created or
exist within social systems. It is important
to consider the social contexts in which risks
occur and that people therefore do not necessarily
share the same perceptions of risk and their
to determine the nature and extent of risk by analysing potential
hazards and evaluating existing conditions of vulnerability
that could pose a potential threat or harm to people, property,
livelihoods and the environment on which they depend.
The process of conducting a
risk assessment is based on a review of both
the technical features of hazards such as their
location, intensity, frequency and probability;
and also the analysis of the physical, social,
economic and environmental dimensions of vulnerability
and exposure, while taking particular account
of the coping capabilities pertinent to the
/ non-structural measures
measures refer to any physical construction to reduce or avoid
possible impacts of hazards, which include engineering measures
and construction of hazard-resistant and protective structures
Non-structural measures refer
to policies, awareness, knowledge development,
public commitment, and methods and operating
practices, including participatory mechanisms
and the provision of information, which can
reduce risk and related impacts.
that meets the needs of the present without compromising the
ability of future generations to meet their own needs. It contains
within it two key concepts: the concept of "needs",
in particular the essential needs of the world's poor, to which
overriding priority should be given; and the idea of limitations
imposed by the state of technology and social organization
on the environment's ability to meet present and the future
needs. (Brundtland Commission, 1987).
Sustainable development is
based on socio-cultural development, political
stability and decorum, economic growth and
ecosystem protection, which all relate to disaster
from technological or industrial accidents, dangerous procedures,
infrastructure failures or certain human activities, which
may cause the loss of life or injury, property damage, social
and economic disruption or environmental degradation.
Some examples: industrial pollution,
nuclear activities and radioactivity, toxic
wastes, dam failures; transport, industrial
or technological accidents (explosions, fires,
determined by physical, social, economic, and environmental
factors or processes, which increase the susceptibility of
a community to the impact of hazards.
For positive factors, which
increase the ability of people to cope with
hazards, see definition of capacity.
occurring in vegetation areas regardless of ignition sources,
damages or benefits.