Disaster risk reduction, like any other field, has a specific vocabulary. Experts use terms to convey specific ideas and information and this language is not always easily understood. It is important to understand the concepts that lie behind the usage and to use the right terminology to avoid presenting a wrong picture.
Below is a list of terms and associated concepts that are commonly used in disaster risk reduction.
Disaster is a term used to refer to “a serious disruption of the functioning of a community or a society at any scale”. It refers to a disruptive event or series of events, not to underlying threats. Disasters lead, among other things, to human, material, economic and environmental losses or impacts.
Disasters may be termed small-scale disasters which affect local communities or large-scale disasters, which require a national or international response. They can be described as frequent or infrequent and they might be slow-onset disasters such as a pandemic, drought, desertification or sea-level rise, or sudden-onset disasters such as earthquakes, volcanic eruptions, flash floods, chemical explosions, and transport accidents.
The term emergency is sometimes used interchangeably with the term disaster, as, for example, in the context of biological and technological hazards or health emergencies.
Disasters originate from hazards – the underlying conditions, processes, phenomena or activities that can lead to serious disruptions or losses. Hazards could be:
Multi-hazard conditions often exist, and when hazards cascade, they can lead to a large-scale disaster. An example is when a geological hazard such as an underwater earthquake leads to a tsunami, which in turn leads to an industrial accident with a radiological hazard, as happened during the Fukushima Daiichi nuclear disaster in Japan in 2011. Multi-hazard conditions are quite common – earthquakes often lead to landslides, droughts lead to famines, storms lead to cold waves or floods, heat waves lead to wildfires, floods lead to dam bursts, and so on.
A range of information on the COVID-19 pandemic from a disaster risk reduction perspective is available on the UNDRR website
Disaster risk is defined as the totality of risk that a disaster poses to a system, society or community in terms of potential loss of life, injury, or destroyed or damaged assets. It comprises different types of potential losses which are often difficult to quantify, but which can at least be assessed in broad terms. Risks are sometimes conceived of as intensive or extensive disaster risks. The former term refers to disasters that are high-severity but mid- to low-frequency, mainly associated with major hazards such as strong earthquakes, active volcanoes, tsunamis or major storms. The latter term refers to the risk of low-severity, high-frequency disasters such as recurring localized floods, landslides and storms
Risk is often understood as a function of hazard, exposure, vulnerability and capacity. Exposure represents the assets that might be impacted by a hazard, including the situation of people, infrastructure, housing, production capacities and other tangible human assets.
Vulnerability is the susceptibility of these assets, or the degree to which someone or something can be affected by a particular hazard. Vulnerability could be rooted in a number of factors, including physical (e.g. unstable locations, closer proximity to hazards), economic (poor pay, no savings and insurance, etc.), social (low status in society, fewer decision-making possibilities, oppressive formal and informal institutional structures) psychological (fears, ideologies, political pressures, mental illness) and physiological factors (age, mobility, disability, etc.).
Capacity is the combination of all the strengths, attributes and resources available to manage and reduce disaster risks and strengthen resilience – and of course the media plays an important role in building disaster resilience, whether by communicating key messages including early warnings, creating awareness, providing information or reassurance, exposing vulnerabilities, focusing attention on specific problems or promoting accountability.
It is important to recognise underlying disaster risk drivers – factors that increase levels of exposure and vulnerability, such as poverty, inequality, climate change, unplanned urbanization, environmental degradation, demographic change and lack of regulations.
Acceptable risk or tolerable risk are terms which refers to the extent to which a disaster risk can be deemed acceptable or tolerable, and it depends on existing social, economic, political, cultural, technical and environmental conditions. In simplistic terms, losing $5 might be an acceptable risk but losing $500 might not be. Residual risk is the risk that remains even after effective disaster risk reduction measures are in place, and for which emergency response and recovery capacities must be maintained.
A full list of terms and their definitions is available on the UNDRR website
A number of different terms are used to convey various interlinked concepts in the risk reduction, risk management, mitigation, disaster prevention, planning and resilience. Not only are the terms important to understanding the nuances of expert opinion, they provide an insight into the different activities and processes that are involved.
Disaster risk reduction is aimed at preventing new disaster risks, reducing existing risks and managing residual risk, all of which contribute to strengthening resilience and therefore to the achievement of sustainable development. It is the policy objective of disaster risk management, and its goals and objectives are defined in disaster risk reduction strategies and plans.
Disaster risk reduction strategies and policies define goals and objectives across different timescales and with concrete targets, indicators and time frames. The United Nations has endorsed the Sendai Framework for Disaster Risk Reduction 2015-2030 as the overarching framework for achieving a substantial reduction of disaster risk and losses.
Local knowledge is increasingly considered critical for the assessment of hazards, vulnerabilities and capacities. It is important to promote community-based disaster risk management from planning through to implementation, monitoring and evaluation of local action for disaster risk reduction. The value of local and indigenous peoples’ approach to disaster risk management is also recognised as central to disaster risk management.
Prevention is the term used for activities and measures to avoid existing and new disaster risks by reducing vulnerability and exposure. Examples include dams or embankments to eliminate flood risks, land-use regulations to prevent settlement in high-risk zones, seismic engineering design, and immunization.
Mitigation means the lessening or minimizing of the adverse impacts of a hazardous event. Mitigation measures include engineering techniques and hazard-resistant construction as well as improved environmental and social policies and public awareness. It should be noted that, in climate change policy, “mitigation” is defined differently, and is the term used for the reduction of greenhouse gas emissions that are the source of climate change.
Resilience is the ability of a system, community or society to resist, adapt to, transform and recover from a disaster in a timely and efficient manner. Resilience is developed through a series of processes that includes recognising risks, mitigating them, planning and building capacity to cope with the disruption of disasters. The media play an important role in building resilience.
Structural and non-structural measures may be implemented to reduce or avoid the possible impacts of hazards. Structural measures include physical constructions such as dams or shelters and the application of engineering techniques or technology to achieve hazard resistance and resilience. Non-structural measures are measures which use knowledge, practice or agreement, through policies and laws, public awareness raising, training and education.
Be accurate in the use of terminology – familiarise yourself with the terminology used by scientists, experts and officials; consult authentic sources for the meanings of fresh terms you encounter.
Try to understand the broad concepts associated with the different aspects of disaster risk reduction.
Simplify the language of experts for your audience – but only if you are sure you are not distorting the meaning. Ask experts and officials to explain what they mean in everyday language.
Consistently upgrade your knowledge to keep track of changes in terminology.
Revisit the foundational concepts and approaches outlined earlier.