What Is a Disaster?
There are different definitions of the word "disaster", but for clarity in this report on disasters with humanitarian implications, the term is defined as an event that has occurred unexpectedly with destructive consequences.
A disaster is a sudden, calamitous event that seriously disrupts the functioning of a community or society and causes human, material, economic or environmental losses that exceed the community's or society's ability to cope using its own resources. Though often caused by nature, disasters can have human origins. The combination of hazards, vulnerability and inability to reduce the potential negative consequences of risk results in disaster. For a disaster to be entered into the database of the UN's International Strategy for Disaster Reduction (ISDR), at least one of the following criteria must be met:
- a report of 10 or more people killed
- a report of 100 people affected
- a declaration of a state of emergency by the relevant government
- a request by the national government for international assistance
Natural Disasters
The following events can be classified as natural disasters:
- Flooding: Significant rise of water level in a stream, lake, reservoir or coastal region.
- Storms: Wind with a speed between 48 and 55 knots.
- Hurricanes: Large-scale, closed-circulation system in the atmosphere above the western Atlantic with low barometric pressure and strong winds that rotate clockwise in the southern hemisphere and counterclockwise in the northern hemisphere. Hurricanes are cyclones of tropical origin with wind speeds of at least 118 kph. A hurricane is a large, rotating storm where the winds move around a relatively calm centre called the "eye". Usually, a hurricane lasts several days. These storms are known as "typhoons" in the western Pacific, "cyclones" in the Indian Ocean and "baguios" in the Philippines.
- Volcanic eruptions: An event caused by acidic lava that flows only a short distance before cooling and solidifying. The build-up of material blocks the vent, which raises the pressure and results in a series of violent blasts where pyroclastic material is ejected.
- Droughts: A naturally occurring phenomenon that occurs when precipitation is significantly below normal levels, causing water levels to drop and vegetation to die. This extended period of dry weather usually lasts longer than expected and leads to significant losses (crop damage, water-supply shortage) in a community.
- Landslides: In general, all varieties of slope movement under the influence of gravity. More strictly, the term refers to down-slope movement of rock and/or earth masses along one or several slide surfaces.
Natural disasters can be divided into three specific groups: hydrometeorological disasters, geophysical disasters and biological disasters.
Hydrometeorological disasters are natural processes or phenomena of atmospheric, hydrological or oceanographic nature that may cause loss of life or injury, property damage, social and economic disruption or environmental degradation. These include floods and wave surges, storms, landslides, avalanches, and droughts and related disasters (extreme temperatures and forest/scrub fires).
Geophysical disasters are natural earth processes or phenomena that may cause loss of life or injury, property damage, social and economic disruption or environmental degradation. These include earthquakes, tsunamis and volcanic eruptions.
Biological disasters are processes of organic origin or those conveyed by biological vectors, including exposure to pathogenic microorganisms, toxins and bioactive substances, which may cause loss of life or injury, property damage, social and economic disruption or environmental degradation. These include epidemics and insect infestations. Human Disasters - Fire: Any fire occurring in vegetation areas, regardless of ignition sources, damages or benefits.
- Death/poor health/general sickness: over and beyond expectation and directly due to a particular external cause of causes.
- Contamination of food products or water or the environment that result in deaths or injuries.
- War/conflict/terrorism. Armed conflict is defined as a political conflict in which armed combat involves the armed forces of at least one state (or one or more armed factions seeking to gain control of all or part of the state), and in which at least 1,000 people have been killed by the fighting during the course of the conflict.
- Workplace violence where the cause of the injuries and/or deaths is directly linked to the working environment of those affected.
Technical Disasters
Danger originating from technological or industrial accidents, dangerous procedures, infrastructure failures or certain human activities, which may cause loss of life or injury, property damage, social and economic disruption or environmental degradation.
Technical disasters include:
- Power cuts and communication failure.
- Explosions involving domestic, industrial and nonindustrial buildings or structures.
- Oil spills and chemical spills. An accidental release occurring during the production, transportation or handling of hazardous chemical substances.
- Nuclear-reactor failures, chemical mishaps.
- Breakdown of computer networks.
- Gas leaks.
- Poisoning of atmosphere or water courses due to industrial sources.
- Cooling/heating/ventilation system failure.
According to ISDR, technical disasters can be classified in three groups: industrial accidents, transport accidents and miscellaneous accidents.
Industrial accidents include chemical spills, collapses of industrial infrastructures, explosions, fires, gas leaks, poisoning and radiation.
Transport accidents include air, rail, road and water transport.
Miscellaneous accidents include the collapse of domestic and nonindustrial structures, explosions and fires.
GLOSSARY
Affected people
People who require immediate assistance during a period of emergency.
Building codes
Ordinances and regulations to control the design, construction, materials, alteration and occupancy of any structure. Building codes ensure human safety and welfare and include both technical and functional standards.
Climate change
The climate of a place or region has changed if there is a statistically significant difference in the measurements of either the mean state or variability of the climate in a place or region over an extended period of time, typically decades or longer.
Coping capacity
The means by which people or organisations use available resources and abilities to face adequately, but in extremis, adverse consequences following a disaster.
Damage assessment
The determination of the extent of physical damage to buildings and man-made structures. Two types of damage assessment are normally carried out: The first evaluates the gross damage to a community determines the level and cost of necessary reconstruction. The second is a detailed, post-disaster, structural analysis of typical buildings to determine the causes of failure and devise methods for modifying the structures so that reconstructed buildings are safer.
Disaster plans
A set of arrangements for preventing, mitigating, preparing for, responding to and recovering from a disaster. A formal record of disaster-management roles, responsibilities, strategies, systems and arrangements.
Disaster response
Activities that occur in the aftermath of a disaster to assist victims and to rehabilitate or reconstruct the physical structures of the community.
Disaster-risk reduction
The conceptual framework of elements aimed at minimising the vulnerabilities and disaster risks throughout a society, avoiding (prevention) or limiting (mitigation and preparedness) the adverse impacts of hazards, within the broad context of sustainable development.
Disaster-risk management
The systematic process of using administrative decisions, organisations, operational skills and capacities to implement policies, strategies and coping capacities of a community to lessen the impact 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) the adverse effects of hazards.
Disaster spectrum
A means of visualizing disasters, showing how pre-disaster and post-disaster activities relate to each other.
Early warning
The provision 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 an effective response.
El Niño-Southern Oscillation (ENSO)
A complex 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.
Emergency
A sudden and usually unforeseen event that calls for immediate measures to minimise its adverse consequences. An emergency occurs after a disaster when an immediate response is required and local capacity is insufficient to address and manage traumatic events. Emergencies may involve deaths, injuries, displacement of people, disease, disability, food insecurity, damage or loss of infrastructure, weakened or destroyed public administration and reduced public safety and security. In disaster-affected countries, these situations often occur simultaneously, straining domestic capacity and disrupting economic and social activity.
Emergency management
Also referred to as disaster management. The organisation and management of resources, roles, and responsibilities to deal with all aspects of emergencies, including preparedness, response and rehabilitation. Emergency management uses plans, structures and predetermined arrangements to coordinate the efforts of governments, voluntary and private agencies and other organisations to deal effectively with the entire spectrum of emergency needs.
Environmental degradation
Processes induced by human behaviour and activities (sometimes combined with natural hazards) that damage the natural-resource base or adversely alter natural processes or ecosystems. Potential effects are varied and may contribute to an increase in vulnerability and the frequency and intensity of natural hazards. Examples include land degradation, deforestation, desertification, wild-land fires, biodiversity loss, climate change, sea-level rise, ozone depletion and land, water and air pollution.
Geographic information systems (GIS)
Analysis that combines relational databases with spatial interpretation and outputs, often in the form of maps. A more elaborate definition is that of spatially referenced computer programmes that capture, store, evaluate, integrate, analyse and display data about the earth.
Hazard
A potentially 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 man-made (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.
Land-use planning
Branch of physical and socioeconomic planning that determines the means and assesses the values or limitations of various options in which land is to be utilised, taking into account the corresponding effects on different segments of the population or interests of a community.
Mitigation
Structural and non-structural measures undertaken to limit the adverse impact of natural hazards, environmental degradation and technological hazards.
Natural Hazards
Natural processes or phenomena occurring in the biosphere that may constitute a damaging event. Natural hazards can be classified according to their geological, hydrometeorological or biological origins.
Preparedness
Activities and measures taken in advance to ensure an effective response to hazards, including the issuance of timely and effective early warnings and the temporary evacuation of people and property from threatened locations.
Prevention
Activities that prevent a natural phenomenon or a potential hazard from having harmful effects on either persons or property. Disaster prevention includes such activities as cloud-seeding to control meteorological patterns, the construction of dams or dikes to prevent flooding and attempts to reduce tectonic tension by such measures as pumping water into earthquake faults.
Reconstruction
Actions taken to re-establish a community after a period of rehabilitation following a disaster. Actions include construction of permanent housing, full restoration of services and complete resumption of the pre-disaster state.
Relief
The provision of assistance or intervention during or immediately following 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.
Resilience - resilient
The capacity 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 organising itself to increase its capacity for learning from past disasters and improving risk-reduction measures.
Risk
The relative degree of probability that a hazardous event will occur. The probability of harmful consequences or expected losses (deaths, injuries, property, livelihoods, disruption of economic activity or environmental damage) resulting from interactions between natural or human-induced hazards and vulnerable conditions. Based on mathematical calculations, risk is the product of hazard and vulnerability. 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 of vulnerability.
Risk Reduction
Selective applications of appropriate techniques and management principles to reduce either the likelihood of an occurrence or its consequences, or both.
Risk assessment/analysis
A methodology to determine the nature and extent of risk by analysing potential hazards and evaluating existing conditions of vulnerability that could pose a potential threat of harm to people, property, livelihoods and the environment on which they depend.
Sustainable development
Development that meets the needs of the present without compromising the ability of future generations to meet their own needs. Sustainable development is based on socio-cultural development, political stability and decorum, economic growth and ecosystem protection, all of which relate to disaster-risk reduction.
Technological Hazards
Danger associated with technological or industrial accidents, infrastructure failures or certain human activities that may cause loss of life or injury, property damage, social and economic disruption or environmental degradation. Sometimes referred to as anthropogenic hazards. Examples include industrial pollution, nuclear release and radioactivity, toxic waste, dam failure, transport and industrial or technological accidents (explosions, fires, spills).
Vulnerability
A condition wherein human settlements or buildings are threatened by virtue of their proximity to a hazard, the quality of their construction, or both. Degree of loss (from 0 percent to 100 percent) resulting from a potential damaging phenomenon.
SOURCES from which this section has summarised these definitions and the glossary.
BizHelp24
www.bizhelp24.com
Center for Disaster Management and Humanitarian Assistance (CDMHA)
www.cdmha.org
Centre for Research on the Epidemiology of Disasters (CRED)
www.cred.be 
Emergency Events Database (EM-DAT)
www.em-dat.net
IDRM International Institute for Disaster Risk Management
www.idrmhome.org
Natural and Environment Disaster Information Exchange System
http://nedies.jrc.it/
United Nations International Strategy for Disaster Reduction (ISDR) "Living with Risk: A global review of disaster reduction initiatives," 2004.
Internationally accepted glossary of basic terms related to disaster management.
www.unisdr.org
www.unisdr.org
United Nations Department of Humanitarian Affairs (UNDHA).
Internationally Agreed Glossary of Basic Terms Related to Disaster Management, Geneva, December 1992.
United Nations Environment Program (UNEP). Glossary on environmental terms
www.nyo.unep.org
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