A disaster is a serious problem occurring over a short or long period of time that causes widespread human, material, economic or environmental loss which exceeds the ability of the affected community or society to cope using its own resources. Developing countries suffer the greatest costs when a disaster hits – more than 95% of all deaths caused by hazards occur in developing countries, and losses due to natural hazards are 20 times greater (as a percentage of GDP) in developing countries than in industrialized countries.
The word disaster is derived from Middle French désastre and that from Old Italian disastro, which in turn comes from the Ancient Greek pejorative prefix δυσ-, (dus-) "bad" and ἀστήρ (aster), "star". The root of the word disaster ("bad star" in Greek) comes from an astrological sense of a calamity blamed on the position of planets.
Disasters are routinely divided into natural or human-made, although complex disasters, where there is no single root cause, are more common in developing countries. A specific disaster may spawn a secondary disaster that increases the impact. A classic example is an earthquake that causes a tsunami, resulting in coastal flooding. Some manufactured disasters have been ascribed to nature such as smog and acid rain.
Some researchers also differentiate between recurring events such as seasonal flooding, and those considered unpredictable.
A natural disaster is a natural process or phenomenon that may cause loss of life, injury or other health impacts, property damage, loss of livelihoods and services, social and economic disruption, or environmental damage.
Various phenomena like earthquakes, landslides, volcanic eruptions, floods, hurricanes, tornadoes, blizzards, tsunamis, cyclones, wildfires, and pandemics are all natural hazards that kill thousands of people and destroy billions of dollars of habitat and property each year. However, the rapid growth of the world's population and its increased concentration often in hazardous environments has escalated both the frequency and severity of disasters. With the tropical climate and unstable landforms, coupled with deforestation, unplanned growth proliferation, non-engineered constructions make the disaster-prone areas more vulnerable. Developing countries suffer more or less chronically from natural disasters due to ineffective communication combined with insufficient budgetary allocation for disaster prevention and management.
Human-instigated disasters are the consequence of technological or human hazards. Examples include war, social unrest, stampedes, fires, transport accidents, industrial accidents, conflicts, oil spills, terrorist attacks, nuclear explosions/nuclear radiation.
Famines may be caused locally by drought, flood, fire, or pestilence, but in modern times there is plenty of food globally, and sustained localized shortages are generally due to government mismanagement, violent conflict, or an economic system that does not distribute food where needed. Earthquakes are mainly hazardous because of human-created buildings and dams; avoiding earthquake-generated tsunamis and landslides is largely a matter of location.
The following table categorizes some disasters and notes first response initiatives.
|Avalanche||The sudden, drastic flow of snow down a slope, occurring when either natural triggers, such as loading from new snow or rain, or artificial triggers, such as explosives or backcountry skiers, overload the snowpack||Shut off utilities; Evacuate building if necessary; Determine impact on the equipment and facilities and any disruption|
|Blizzard||A severe snowstorm characterized by very strong winds and low temperatures||Power off all equipment; listen to blizzard advisories; Evacuate area, if unsafe; Assess damage|
|Earthquake||The shaking of the earth's crust, caused by underground volcanic forces of breaking and shifting rock beneath the earth's surface||Shut off utilities; Evacuate building if necessary; Determine impact on the equipment and facilities and any disruption|
|Fire (wild)||Fires that originate in uninhabited areas and which pose the risk to spread to inhabited areas||Attempt to suppress fire in early stages; Evacuate personnel on alarm, as necessary; Notify fire department; Shut off utilities; Monitor weather advisories|
|Flood||Flash flooding: Small creeks, gullies, dry streambeds, ravines, culverts or even low-lying areas flood quickly||Monitor flood advisories; Determine flood potential to facilities; Pre-stage emergency power generating equipment; Assess damage|
|Freezing rain||Rain occurring when outside surface temperature is below freezing||Monitor weather advisories; arrange for snow and ice removal|
|Heat wave||A prolonged period of excessively hot weather relative to the usual weather pattern of an area and relative to normal temperatures for the season||Listen to weather advisories; Power-off all servers after a graceful shutdown if there is imminent potential of power failure; Shut down main electric circuit usually located in the basement or the first floor|
|Hurricane||Heavy rains and high winds||Power off all equipment; listen to hurricane advisories; Evacuate area, if flooding is possible; Check gas, water and electrical lines for damage; Do not use telephones, in the event of severe lightning; Assess damage|
|Landslide||Geological phenomenon which includes a range of ground movement, such as rock falls, deep failure of slopes and shallow debris flows||Shut off utilities; Evacuate building if necessary; Determine impact on the equipment and facilities and any disruption|
|Lightning strike||An electrical discharge caused by lightning, typically during thunderstorms||Power off all equipment; listen to hurricane advisories; Evacuate area, if flooding is possible; Check gas, water and electrical lines for damage; Do not use telephones, in the event of severe lightning; Assess damage|
|Limnic eruption||The sudden eruption of carbon dioxide from deep lake water|
|Tornado||Violent rotating columns of air which descend from severe thunderstorm cloud systems||Monitor tornado advisories; Power off equipment; Shut off utilities (power and gas); Assess damage once storm passes|
|Tsunami||A series of waves hitting shores strongly, mainly caused by the displacement of a large volume of a body of water, typically an ocean or a large lake, usually caused by earthquakes, volcanic eruptions, underwater explosions, landslides, glacier calvings, meteorite impacts and other disturbances above or below water||Power off all equipment; listen to tsunami advisories; Evacuate area, if flooding is possible; Check gas, water and electrical lines for damage; Assess damage|
|Volcanic eruption||The release of hot magma, volcanic ash and/or gases from a volcano|
|Human-made||Bioterrorism||The intentional release or dissemination of biological agents as a means of coercion||Get information immediately from public health officials via the news media as to the right course of action; If you think you have been exposed, quickly remove your clothing and wash off your skin; put on a HEPA to help prevent inhalation of the agent|
|Civil unrest||A disturbance caused by a group of people that may include sit-ins and other forms of obstructions, riots, sabotage and other forms of crime, and which is intended to be a demonstration to the public and the government, but can escalate into general chaos||Contact local police or law enforcement|
|Fire (urban)||Even with strict building fire codes, people still perish in fires||Attempt to suppress fire in early stages; Evacuate personnel on alarm, as necessary; Notify fire department; Shut off utilities; Monitor weather advisories|
|Hazardous material spills||The escape of solids, liquids, or gases that can harm people, other living organisms, property or the environment, from their intended controlled environment such as a container.||Leave the area and call the local fire department for help. If anyone was affected by the spill, call your local Emergency Medical Services line|
|Nuclear and radiation accidents||An event involving the significant release of radioactivity to the environment or a reactor core meltdown and which leads to major undesirable consequences to people, the environment, or the facility||Recognize that a CBRN incident has or may occur. Gather, assess and disseminate all available information to first responders. Establish an overview of the affected area. Provide and obtain regular updates to and from first responders.|
|Power failure||Caused by summer or winter storms, lightning or construction equipment digging in the wrong location||Wait 5–10 minutes; turn off all servers after a graceful shutdown; do not use telephones, in the event of severe lightning; shut down main electric circuit usually located in the basement or the first floor|
|The Wikibook History has a page on the topic of: Historical Disasters and Tragedies|