A hazard is a potential source of harm. Substances, events, or circumstances can constitute hazards when their nature would potentially allow them to cause damage to health, life, property, or any other interest of value. The probability of that harm being realized in a specific incident, combined with the magnitude of potential harm, make up its risk. This term is often used synonymously in colloquial speech.
Hazards can be classified in several ways which are not mutually exclusive. They can be classified by causing actor (for example, natural or anthropogenic), by physical nature (e.g. biological or chemical) or by type of damage (e.g., health hazard or environmental hazard). Examples of natural disasters with highly harmful impacts on a society are floods, droughts, earthquakes, tropical cyclones, lightning strikes, volcanic activity and wildfires. Technological and anthropogenic hazards include, for example, structural collapses, transport accidents, accidental or intentional explosions, and release of toxic materials.
The term climate hazard is used in the context of climate change. These are hazards that stem from climate-related events and can be associated with global warming, such as wildfires, floods, droughts, sea level rise. Climate hazards can combine with other hazards and result in compound event losses (see also loss and damage). For example, the climate hazard of heat can combine with the hazard of poor air quality. Or the climate hazard flooding can combine with poor water quality.
In physics terms, common theme across many forms of hazards is the presence of energy that can cause damage, as it can happen with chemical energy, mechanical energy or thermal energy. This damage can affect different valuable interests, and the severity of the associated risk varies.
Definition A hazard is defined as "the potential occurrence of a natural or human-induced physical event or trend that may cause loss of life, injury, or other health impacts, as well as damage and loss to property, infrastructure, livelihoods, service provision, ecosystems and environmental resources."IPCC, 2021: Annex VII: Glossary [Matthews, J.B.R., V. Möller, R. van Diemen, J.S. Fuglestvedt, V. Masson-Delmotte, C. Méndez, S. Semenov, A. Reisinger (eds.)]. In Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change [Masson-Delmotte, V., P. Zhai, A. Pirani, S.L. Connors, C. Péan, S. Berger, N. Caud, Y. Chen, L. Goldfarb, M.I. Gomis, M. Huang, K. Leitzell, E. Lonnoy, J.B.R. Matthews, T.K. Maycock, T. Waterfield, O. Yelekçi, R. Yu, and B. Zhou (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, pp. 2215–2256, doi:10.1017/9781009157896.022.
A hazard only exists if there is a pathway to exposure. For example, the center of the Earth consists of molten material at very high temperatures, which would be a severe hazard if contact could be made with the core. However, since that is not feasible, the Earth's core currently poses no hazard.
The frequency and severity of hazards are important aspects for risk management. Hazards may also be assessed in relation to the impact that they have.
In defining hazard Keith Smith argues that what may be defined as the hazard is only a hazard if there is the presence of humans to make it a hazard. In this regard, human sensitivity to environmental hazards is a combination of both physical exposure (natural and/or technological events at a location related to their statistical variability) and human vulnerability (about social and economic tolerance of the same location).
Relationship with other terms
Disaster
An example of the distinction between a natural hazard and a disaster is that an earthquake is the hazard which caused the 1906 San Francisco earthquake disaster.
A natural disaster is the highly harmful impact on a society or community following a natural hazard event. The term "disaster" itself is defined as follows: "Disasters are serious disruptions to the functioning of a community that exceed its capacity to cope using its own resources. Disasters can be caused by natural, man-made and technological hazards, as well as various factors that influence the exposure and vulnerability of a community."
The US Federal Emergency Management Agency (FEMA) explains the relationship between natural disasters and natural hazards as follows: "Natural hazards and natural disasters are related but are not the same. A natural hazard is the threat of an event that will likely have a negative impact. A natural disaster is the negative impact following an actual occurrence of natural hazard in the event that it significantly harms a community.
Disaster can take various forms, including hurricane, volcano, tsunami, earthquake, drought, famine, plague, disease, rail crash, car crash, tornado, deforestation, flooding, toxic release, and spills (oil, chemicals).
A disaster hazard is an extreme geophysical event that is capable of causing a disaster. 'Extreme' in this case means a substantial variation in either the positive or the negative direction from the normal trend; flood disasters can result from exceptionally high precipitation and river discharge, and drought is caused by exceptionally low values. The fundamental determinants of hazard and the risk of such hazards occurring is timing, location, magnitude and frequency. For example, magnitudes of earthquakes are measured on the Richter scale from 1 to 10, whereby each increment of 1 indicates a tenfold increase in severity. The magnitude-frequency rule states that over a significant period of time many small events and a few large ones will occur. Hurricanes and typhoons on the other hand occur between 5 degrees and 25 degrees north and south of the equator, tending to be seasonal phenomena that are thus largely recurrent in time and predictable in location due to the specific climate variables necessary for their formation.
Risk and vulnerability
The terms hazard and risk are often used interchangeably. However, in terms of risk assessment, these are two very distinct terms. A hazard is an agent that can cause harm or damage to humans, property, or the environment. Risk is the probability that exposure to a hazard will lead to a negative consequence, or more simply, a hazard poses no risk if there is no exposure to that hazard.
Risk is a combination of hazard, exposure and vulnerability. Text was copied from this source, which is available under a Creative Commons Attribution 4.0 International License For example in terms of water security: examples of hazards are droughts, floods and decline in water quality. Bad infrastructure and bad governance lead to high exposure to risk.
Risk can be defined as the likelihood or probability of a given hazard of a given level causing a particular level of loss of damage. The elements of risk are populations, communities, the built environment, the natural environment, economic activities and services which are under threat of disaster in a given area.
Another definition of risk is "the probable frequency and probable magnitude of future losses". This definition also focuses on the probability of future loss whereby the degree of vulnerability to hazard represents the level of risk on a particular population or environment. The threats posed by a hazard are: Hazards to people – death, injury, disease and stress Hazards to goods – property damage and economic loss Hazards to environment –loss of flora and fauna, pollution and loss of amenity
Classifications Hazards can be classified in several ways. These categories are not mutually exclusive which means that one hazard can fall into several categories. For example, water pollution with toxic chemicals is an anthropogenic hazard as well as an environmental hazard.
One of the classification methods is by specifying the origin of the hazard. One key concept in identifying a hazard is the presence of stored energy that, when released, can cause damage. The stored energy can occur in many forms: chemical, mechanical, thermal, radioactive, electrical, etc.
The United Nations Office for Disaster Risk Reduction (UNDRR) explains that "each hazard is characterized by its location, intensity or magnitude, frequency and probability".
A distinction can also be made between rapid-onset natural hazards, technological hazards, and social hazards, which are described as being of sudden occurrence and relatively short duration, and the consequences of longer-term environmental degradation such as desertification and drought.
Hazards may be grouped according to their characteristics. These factors are related to geophysical events, which are not process specific: Areal extent of damage zone Intensity of impact at a point Duration of impact at a point Rate of onset of the event Predictability of the event
By causing actor
Natural hazard
Damage to valuable human interests can occur due to phenomena and processes of the natural environment. Natural disasters such as earthquakes, floods, volcanoes and tsunami have threatened people, society, the natural environment, and the built environment, particularly more vulnerable people, throughout history, and in some cases, on a day-to-day basis. According to the Red Cross, each year 130,000 people are killed, 90,000 are injured and 140 million are affected by unique events known as natural disasters.
Potentially dangerous phenomena which are natural or predominantly natural (for example, exceptions are intentional floods) can be classified in these categories: Meteorological and hydrological hazards, e.g. lightning, storm, flood, sandstorm, fog, rogue wave, tsunami, snow, limnic eruption, cold wave, heat wave Geological hazards Earthquake Volcanism, which can cause a wide range of events, such as lava flow and ash fall Surface or near-surface events, especially erosion and mass wasting (e.g. landslide) Extraterrestrial hazards, e.g. solar storm, impact event
Natural hazards can be influenced by human actions in different ways and to varying degrees, e.g. land-use change, drainage and construction. Humans play a central role in the existence of natural hazards because "it is only when people and their possessions get in the way of natural processes that hazard exists".
A natural hazard can be considered as a geophysical event when it occurs in extremes and a human factor is involved that may present a risk. There may be an acceptable variation of magnitude which can vary from the estimated normal or average range with upper and lower limits or thresholds. In these extremes, the natural occurrence may become an event that presents a risk to the environment or people. For example, above-average wind speeds resulting in a tropical depression or hurricane according to intensity measures on the Saffir–Simpson scale will provide an extreme natural event that may be considered a hazard.
Seismic hazard
Tsunamis can be caused by geophysical hazards, such as in the 2004 Indian Ocean earthquake and tsunami. The earthquake caused a massive tsunami with waves up to 30 m (100 ft) high, referred to by British and Commonwealth media as the Boxing Day tsunami, after the Boxing Day holiday, or the Asian tsunami, which devastated communities along the surrounding coasts of the Indian Ocean, killing an estimated 227,898 people in 14 countries, especially in Aceh in Indonesia, Sri Lanka, Tamil Nadu in India, and Khao Lak in Thailand.
Although generally a natural phenomenon, earthquakes can sometimes be induced by human interventions, such as injection wells, large underground nuclear explosions, excavation of mines, or reservoirs.
Volcanic hazard
Anthropogenic hazard