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.
140-693: 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
280-608: A god or gods are angry with women's independent, freethinking behavior, such as dressing 'immodestly', having sex or abortions. For example, Hindutva party Hindu Makkal Katchi and others blamed women's struggle for the right to enter the Sabarimala temple for the August 2018 Kerala floods , purportedly inflicted by the angry god Ayyappan . During and after natural disasters, routine health behaviors become interrupted. In addition, health care systems may have broken down as
420-502: A ground blizzard . Blizzards can impact local economic activities, especially in regions where snowfall is rare. The Great Blizzard of 1888 affected the United States, when many tons of wheat crops were destroyed. In Asia, the 1972 Iran blizzard and the 2008 Afghanistan blizzard , were the deadliest blizzards in history; in the former, an area the size of Wisconsin was entirely buried in snow. The 1993 Superstorm originated in
560-599: A microorganism , virus or toxin (from a biological source) that can affect health . Many biological hazards are associated with food, including certain viruses , parasites , fungi , bacteria , and plant and seafood toxins . Pathogenic Campylobacter and Salmonella are common foodborne biological hazards. The hazards from these bacteria can be avoided through risk mitigation steps such as proper handling, storing , and cooking of food. Diseases can be enhanced by human factors such as poor sanitation or by processes such as urbanization . A chemical can be considered
700-886: A mid-ocean ridge , such as the Mid-Atlantic Ridge , has volcanoes caused by divergent tectonic plates whereas the Pacific Ring of Fire has volcanoes caused by convergent tectonic plates. Volcanoes can also form where there is stretching and thinning of the crust's plates, such as in the East African Rift , the Wells Gray-Clearwater volcanic field , and the Rio Grande rift in North America. Volcanism away from plate boundaries has been postulated to arise from upwelling diapirs from
840-748: A tsunami occurred near Fukushima, Japan and spread through the Pacific Ocean. Some of the 18 natural hazards included in the National Risk Index of FEMA now have a higher probability of occurring, and at higher intensity, due to the effects of climate change . This applies to heat waves, droughts, wildfire and coastal flooding. A heat wave is a period of unusually and excessively hot weather. Heat waves are rare and require specific combinations of weather events to take place, and may include temperature inversions , katabatic winds , or other phenomena. The worst heat wave in recent history
980-544: A vulnerable community . It results from the combination of the hazard and the exposure of a vulnerable society. Nowadays it is hard to distinguish between natural and human-made disasters. The term natural disaster was already challenged in 1976. Human choices in architecture, fire risk, and resource management can cause or worsen natural disasters. Climate change also affects how often disasters due to extreme weather hazards happen. These " climate hazards " are floods, heat waves, wildfires, tropical cyclones, and
1120-438: A vulnerable population . 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
1260-461: A bottleneck in human evolution, and killed three-quarters of all plant life in the northern hemisphere. However, there is considerable debate regarding the veracity of this theory. The main danger from a supervolcano is the immense cloud of ash, which has a disastrous global effect on climate and temperature for many years. A tsunami (plural: tsunamis or tsunami; from Japanese: 津波, lit. "harbour wave"; English pronunciation: /tsuːˈnɑːmi/), also known as
1400-474: 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,
1540-467: A cloud (generally after cooling) and settle thickly in nearby locations. When mixed with water, this forms a concrete-like material. In sufficient quantities, ash may cause roofs to collapse under its weight. Even small quantities will harm humans if inhaled – it has the consistency of ground glass and therefore causes laceration to the throat and lungs. Volcanic ash can also cause abrasion damage to moving machinery such as engines. The main killer of humans in
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#17327758198011680-529: A consequence of human-induced climate change . A tornado is a violent and dangerous rotating column of air that is in contact with both the surface of the Earth and a cumulonimbus cloud , or, in rare cases, the base of a cumulus cloud . It is also referred to as a twister or a cyclone , although the word cyclone is used in meteorology in a wider sense to refer to any closed low pressure circulation. Tornadoes come in many shapes and sizes but typically take
1820-552: A cumulative biological effect, while others are metabolically eliminated over time. Other chemical hazards may depend on concentration or total quantity for their effects. Some harmful chemicals occur naturally in certain geological formations, such as arsenic . Other chemicals include products with commercial uses, such as agricultural and industrial chemicals, as well as products developed for home use. A variety of chemical hazards have been identified. However, every year companies produce more new chemicals to fill new needs or to take
1960-407: A few kilometers before dissipating. The most extreme tornadoes can attain wind speeds of more than 480 km/h (300 mph), stretch more than 3 km (2 mi) across, and stay on the ground for perhaps more than 100 km (60 mi). Blizzards are severe winter storms characterized by heavy snow and strong winds. When high winds stir up snow that has already fallen, it is known as
2100-437: A graduated spectrum, with much overlap between categories, and does not always fit neatly into only one of these three separate categories. The USGS defines a volcano as "erupting" whenever the ejection of magma from any point on the volcano is visible, including visible magma still contained within the walls of the summit crater. While there is no international consensus among volcanologists on how to define an active volcano,
2240-399: A hazard are: 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
2380-538: A hazard if by its intrinsic properties it can cause harm or danger to humans, property, or the environment. Health hazards associated with chemicals are dependent on the dose or amount of the chemical. For example, iodine in the form of potassium iodate is used to produce iodised salt . When applied at a rate of 20 mg of potassium iodate per 1000 mg of table salt, the chemical is beneficial in preventing goitre , while iodine intakes of 1200–9500 mg in one dose has been known to cause death. Some chemicals have
2520-494: A mechanical hazard. Hazard identification of new machines and/or industrial processes occurs at various stages in the design of the new machine or process. These hazard identification studies focus mainly on deviations from the intended use or design and the harm that may occur as a result of these deviations. These studies are regulated by various agencies such as the Occupational Safety and Health Administration and
2660-535: 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
2800-411: 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." A hazard only exists if there is a pathway to exposure. As an example, the center of the Earth consists of molten material at very high temperatures which would be
2940-421: A natural phenomenon, earthquakes can sometimes be induced by human interventions, such as injection wells , large underground nuclear explosions , excavation of mines , or reservoirs . Anthropogenic hazards, or human-induced hazards, are "induced entirely or predominantly by human activities and choices". These can be societal, technological or environmental hazards . Technological hazards are created by
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#17327758198013080-443: A paper was published suggesting a new definition for the word 'volcano' that includes processes such as cryovolcanism . It suggested that a volcano be defined as 'an opening on a planet or moon's surface from which magma , as defined for that body, and/or magmatic gas is erupted.' This article mainly covers volcanoes on Earth. See § Volcanoes on other celestial bodies and cryovolcano for more information. The word volcano
3220-420: A result of the disaster, further reducing access to contraceptives. Unprotected intercourse during this time can lead to increased rates of childbirth, unintended pregnancies and sexually transmitted infections (STIs). Pregnant women are one of the groups disproportionately affected by natural disasters. Inadequate nutrition, little access to clean water, lack of health-care services and psychological stress in
3360-411: A row of temperatures exceeding 40 °C (104 °F), with some regional areas sweltering through much higher temperatures. A flood is an overflow of water that 'submerges' land. The EU Floods Directive defines a flood as a temporary covering of land that is usually dry with water. In the sense of 'flowing water', the word may also be applied to the inflow of the tides . Flooding may result from
3500-405: A seismic sea wave or tidal wave, is a series of waves in a water body caused by the displacement of a large volume of water, generally in an ocean or a large lake. Tsunamis can be caused by undersea earthquakes such as the 2004 Boxing Day tsunami , or by landslides such as the one in 1958 at Lituya Bay, Alaska , or by volcanic eruptions such as the ancient eruption of Santorini . On March 11, 2011,
3640-402: A severe hazard if contact was made with the core. However, there is no feasible way of making contact with the core, therefore the center of the Earth 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
3780-450: A short warning time and are short-lived. Slow onset events can also be very damaging, for example drought is a natural hazards that develops slowly, sometimes over years. A natural disaster may cause loss of life, injury or other health impacts, property damage, loss of livelihoods and services, social and economic disruption, or environmental damage. Globally, the total number of deaths from natural disasters has been reduced by 75% over
3920-559: A slope prone to failure. In many cases, the landslide is triggered by a specific event (such as a heavy rainfall , an earthquake , a slope cut to build a road, and many others), although this is not always identifiable. An avalanche is a rapid flow of snow down a slope , such as a hill or mountain. Avalanches can be triggered spontaneously, by factors such as increased precipitation or snowpack weakening, or by external means such as humans, other animals, and earthquakes . Primarily composed of flowing snow and air, large avalanches have
4060-411: 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
4200-566: A threat to humans and property, as well as wildlife . One example for a notable wildfire is the 1871 Peshtigo Fire in the United States, which killed at least 1700 people. Another one is the 2009 Victorian bushfires in Australia (collectively known as " Black Saturday bushfires "). In that year, a summer heat wave in Victoria, Australia, created conditions which fueled the massive bushfires in 2009. Melbourne experienced three days in
4340-704: A variety of measures have been taken to limit human exposure to these microorganisms through food safety, good personal hygiene, and education. The potential for new biological hazards also exists through the discovery of new microorganisms and the development of new genetically modified (GM) organisms. The use of new GM organisms is regulated by various governmental agencies. The US Environmental Protection Agency (EPA) controls GM plants that produce or resist pesticides (i.e. Bt corn and Roundup ready crops ). The US Food and Drug Administration (FDA) regulates GM plants that will be used as food or for medicinal purposes. Biological hazards can include medical waste or samples of
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4480-565: A variety of negative effects on non-target organisms. DDT can build up, or bioaccumulate, in birds, resulting in thinner-than-normal eggshells, which can break in the nest. The organochlorine pesticide dieldrin has been linked to Parkinson's disease . Corrosive chemicals like sulfuric acid , which is found in car batteries and research laboratories, can cause severe skin burns. Many other chemicals used in industrial and laboratory settings can cause respiratory, digestive, or nervous system problems if they are inhaled, ingested, or absorbed through
4620-632: A volcano is largely determined by the composition of the lava it erupts. The viscosity (how fluid the lava is) and the amount of dissolved gas are the most important characteristics of magma, and both are largely determined by the amount of silica in the magma. Magma rich in silica is much more viscous than silica-poor magma, and silica-rich magma also tends to contain more dissolved gases. Lava can be broadly classified into four different compositions: Mafic lava flows show two varieties of surface texture: ʻAʻa (pronounced [ˈʔaʔa] ) and pāhoehoe ( [paːˈho.eˈho.e] ), both Hawaiian words. ʻAʻa
4760-555: A volcano is of a conical mountain, spewing lava and poisonous gases from a crater at its summit; however, this describes just one of the many types of volcano. The features of volcanoes are varied. The structure and behaviour of volcanoes depend on several factors. Some volcanoes have rugged peaks formed by lava domes rather than a summit crater while others have landscape features such as massive plateaus . Vents that issue volcanic material (including lava and ash ) and gases (mainly steam and magmatic gases) can develop anywhere on
4900-465: A volcano that has experienced one or more eruptions that produced over 1,000 cubic kilometres (240 cu mi) of volcanic deposits in a single explosive event. Such eruptions occur when a very large magma chamber full of gas-rich, silicic magma is emptied in a catastrophic caldera -forming eruption. Ash flow tuffs emplaced by such eruptions are the only volcanic product with volumes rivalling those of flood basalts . Supervolcano eruptions, while
5040-518: A wide range of ground movements, such as rockfalls , mudflows , shallow or deep-seated slope failures and debris flows . Landslides occur in a variety of environments, characterized by either steep or gentle slope gradients, from mountain ranges to coastal cliffs or even underwater, in which case they are called submarine landslides . Gravity is the primary driving force for a landslide to occur, but there are other factors affecting slope stability that produce specific conditions that make
5180-739: Is a volcanic field of over 60 cinder cones. Based on satellite images, it has been suggested that cinder cones might occur on other terrestrial bodies in the Solar system too; on the surface of Mars and the Moon. Stratovolcanoes (composite volcanoes) are tall conical mountains composed of lava flows and tephra in alternate layers, the strata that gives rise to the name. They are also known as composite volcanoes because they are created from multiple structures during different kinds of eruptions. Classic examples include Mount Fuji in Japan, Mayon Volcano in
5320-662: Is a depression or hole in the ground caused by some form of collapse of the surface layer. When natural erosion, human mining or underground excavation makes the ground too weak to support the structures built on it, the ground can collapse and produce a sinkhole . Coastal erosion is a physical process by which shorelines in coastal areas around the world shift and change, primarily in response to waves and currents that can be influenced by tides and storm surge. Coastal erosion can result from long-term processes (see also beach evolution ) as well as from episodic events such as tropical cyclones or other severe storm events. Coastal erosion
5460-815: Is a result of a natural hazard impacting a vulnerable community . But disasters can be avoided. Earthquakes, droughts, floods, storms, and other events lead to disasters because of human action and inaction. Poor land and policy planning and deregulation can create worse conditions. They often involve development activities that ignore or fail to reduce the disaster risks . Nature alone is blamed for disasters even when disasters result from failures in development. Disasters also result from failure of societies to prepare. Examples for such failures include inadequate building norms, marginalization of people, inequities, overexploitation of resources, extreme urban sprawl and climate change . Defining disasters as solely natural events has serious implications when it comes to understanding
5600-437: Is because modern technological living uses certain toxic or poisonous materials in the electronics and chemical industries. Which, when they are in use or transported, are usually safely contained or encapsulated and packaged to avoid any exposure. In the waste stream, the waste products exterior or encapsulation breaks or degrades and there is a release and exposure to hazardous materials into the environment, for people working in
5740-412: Is characterized by a rough, clinkery surface and is the typical texture of cooler basalt lava flows. Pāhoehoe is characterized by its smooth and often ropey or wrinkly surface and is generally formed from more fluid lava flows. Pāhoehoe flows are sometimes observed to transition to ʻaʻa flows as they move away from the vent, but never the reverse. More silicic lava flows take the form of block lava, where
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5880-565: Is derived from the name of Vulcano , a volcanic island in the Aeolian Islands of Italy whose name in turn comes from Vulcan , the god of fire in Roman mythology . The study of volcanoes is called volcanology , sometimes spelled vulcanology . According to the theory of plate tectonics, Earth's lithosphere , its rigid outer shell, is broken into sixteen larger and several smaller plates. These are in slow motion, due to convection in
6020-584: Is expressed using the volcanic explosivity index (VEI), which ranges from 0 for Hawaiian-type eruptions to 8 for supervolcanic eruptions. As of December 2022 , the Smithsonian Institution 's Global Volcanism Program database of volcanic eruptions in the Holocene Epoch (the last 11,700 years) lists 9,901 confirmed eruptions from 859 volcanoes. The database also lists 1,113 uncertain eruptions and 168 discredited eruptions for
6160-415: Is listed here as a climate hazard is because "warming temperatures may result in higher evapotranspiration , in turn leading to drier soils". Waterborne diseases are also connected to climate hazards. 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
6300-470: Is no exposure to that hazard. Risk is a combination of hazard, exposure and vulnerability . 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,
6440-569: Is no recycling facility, plastics have flooded the camps' streets and surroundings. In contrast, the Azraq camp in Jordan for refugees from Syria has waste management services; of 20.7 tonnes of waste produced per day, 15% is recyclable. Because of the social, political and cultural context of many places throughout the world, women are often disproportionately affected by disaster. In the 2004 Indian Ocean tsunami, more women died than men, partly due to
6580-512: Is one of the most significant coastal hazards. It forms a threat to infrastructure, capital assets and property. Volcanoes can cause widespread destruction and consequent disaster in several ways. One hazard is the volcanic eruption itself, with the force of the explosion and falling rocks able to cause harm. Lava may also be released during the eruption of a volcano; as it leaves the volcano, it can destroy buildings, plants and animals due to its extreme heat. In addition, volcanic ash may form
6720-537: Is one of the several tuyas in the area of the Tuya River and Tuya Range in northern British Columbia. Tuya Butte was the first such landform analysed and so its name has entered the geological literature for this kind of volcanic formation. The Tuya Mountains Provincial Park was recently established to protect this unusual landscape, which lies north of Tuya Lake and south of the Jennings River near
6860-644: Is referred to as a "typhoon"; a "cyclone" occurs in the South Pacific and Indian Ocean. The deadliest hurricane ever was the 1970 Bhola cyclone ; the deadliest Atlantic hurricane was the Great Hurricane of 1780 , which devastated Martinique, St. Eustatius and Barbados. Another notable hurricane is Hurricane Katrina , which devastated the Gulf Coast of the United States in 2005. Hurricanes may become more intense and produce more heavy rainfall as
7000-474: Is the most important driver of economic losses. However, part of these are also due to human-induced climate change . During emergencies such as natural disasters and armed conflicts more waste may be produced, while waste management is given low priority compared with other services. Existing waste management services and infrastructures can be disrupted, leaving communities with unmanaged waste and increased littering. Under these circumstances human health and
7140-471: Is typically low in silica, shield volcanoes are more common in oceanic than continental settings. The Hawaiian volcanic chain is a series of shield cones, and they are common in Iceland , as well. Lava domes are built by slow eruptions of highly viscous lava. They are sometimes formed within the crater of a previous volcanic eruption, as in the case of Mount St. Helens , but can also form independently, as in
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#17327758198017280-516: Is used in the context of climate change , for example in the IPCC Sixth Assessment Report . These are hazards that stem from climate-related events such as wildfires , floods, droughts, sea level rise . Climate hazards in the context of water include: Increased temperatures, changes in rainfall patterns between the wet and dry season (increased rainfall variability) and sea level rise. The reason why increasing temperatures
7420-406: 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
7560-617: The Cascade Volcanoes or the Japanese Archipelago , or the eastern islands of Indonesia . Hotspots are volcanic areas thought to be formed by mantle plumes , which are hypothesized to be columns of hot material rising from the core-mantle boundary. As with mid-ocean ridges, the rising mantle rock experiences decompression melting which generates large volumes of magma. Because tectonic plates move across mantle plumes, each volcano becomes inactive as it drifts off
7700-540: The Japanese Ministry of the Environment . Some of this waste, mostly plastic and styrofoam washed up on the coasts of Canada and the United States in late 2011. Along the west coast of the United States, this increased the amount of litter by a factor of 10 and may have transported alien species. Storms are also important generators of plastic litter. A study by Lo et al. (2020) reported a 100% increase in
7840-508: The National Highway Traffic Safety Administration . Engineering hazards occur when human structures fail (e.g. building or structural collapse , bridge failures , dam failures ) or the materials used in their construction prove to be hazardous. Societal hazards can arise from civil disorders , explosive remnants of war , violence , crowd accidents , financial crises , etc. However,
7980-684: The Spitak Earthquake ). The Asia-Pacific region is the world's most disaster prone region. A person in Asia-Pacific is five times more likely to be hit by a natural disaster than someone living in other regions. Between 1995 and 2015, the greatest number of natural disasters occurred in America, China and India. In 2012, there were 905 natural disasters worldwide, 93% of which were weather-related disasters. Overall costs were US$ 170 billion and insured losses $ 70 billion. 2012
8120-480: The United Nations Office for Disaster Risk Reduction (UNDRR) Hazard Definition & Classification Review (Sendai Framework 2015 - 2030) specifically excludes armed conflict from the anthropogenic hazard category, as these hazards are already recognised under international humanitarian law. In managing waste many hazardous materials are put in the domestic and commercial waste stream . In part this
8260-438: 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
8400-752: The core–mantle boundary , 3,000 kilometres (1,900 mi) deep within Earth. This results in hotspot volcanism , of which the Hawaiian hotspot is an example. Volcanoes are usually not created where two tectonic plates slide past one another. Large eruptions can affect atmospheric temperature as ash and droplets of sulfuric acid obscure the Sun and cool Earth's troposphere . Historically, large volcanic eruptions have been followed by volcanic winters which have caused catastrophic famines. Other planets besides Earth have volcanoes. For example, volcanoes are very numerous on Venus. Mars has significant volcanoes. In 2009,
8540-834: The landform and may give rise to smaller cones such as Puʻu ʻŌʻō on a flank of Kīlauea in Hawaii. Volcanic craters are not always at the top of a mountain or hill and may be filled with lakes such as with Lake Taupō in New Zealand. Some volcanoes can be low-relief landform features, with the potential to be hard to recognize as such and be obscured by geological processes. Other types of volcano include cryovolcanoes (or ice volcanoes), particularly on some moons of Jupiter , Saturn , and Neptune ; and mud volcanoes , which are structures often not associated with known magmatic activity. Active mud volcanoes tend to involve temperatures much lower than those of igneous volcanoes except when
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#17327758198018680-552: The FDA regulates new chemicals used in foods or as drugs. The potential hazards of these chemicals can be identified by performing a variety of tests before the authorization of usage. The number of tests required and the extent to which the chemicals are tested varies, depending on the desired usage of the chemical. Chemicals designed as new drugs must undergo more rigorous tests than those used as pesticides. Pesticides, which are normally used to control unwanted insects and plants, may cause
8820-718: The Gulf of Mexico and traveled north, causing damage in 26 American states as well as in Canada and leading to more than 300 deaths. Volcano A volcano is a rupture in the crust of a planetary-mass object , such as Earth , that allows hot lava , volcanic ash , and gases to escape from a magma chamber below the surface. The process that forms volcanoes is called volcanism . On Earth, volcanoes are most often found where tectonic plates are diverging or converging , and because most of Earth's plate boundaries are underwater, most volcanoes are found underwater. For example,
8960-416: The National Risk Index of FEMA: avalanche , coastal flooding , cold wave , drought , earthquake , hail , heat wave , tropical cyclone , ice storm , landslide , lightning , riverine flooding, strong wind, tornado , tsunami , volcanic activity , wildfire , winter weather. In addition, there are also dust storms . The term natural disaster has been called a misnomer already in 1976. A disaster
9100-622: The Philippines, and Mount Vesuvius and Stromboli in Italy. Ash produced by the explosive eruption of stratovolcanoes has historically posed the greatest volcanic hazard to civilizations. The lavas of stratovolcanoes are higher in silica, and therefore much more viscous, than lavas from shield volcanoes. High-silica lavas also tend to contain more dissolved gas. The combination is deadly, promoting explosive eruptions that produce great quantities of ash, as well as pyroclastic surges like
9240-503: 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
9380-613: The USGS defines a volcano as active whenever subterranean indicators, such as earthquake swarms , ground inflation, or unusually high levels of carbon dioxide or sulfur dioxide are present. The USGS defines a dormant volcano as any volcano that is not showing any signs of unrest such as earthquake swarms, ground swelling, or excessive noxious gas emissions, but which shows signs that it could yet become active again. Many dormant volcanoes have not erupted for thousands of years, but have still shown signs that they may be likely to erupt again in
9520-453: The aftermath of the disaster can lead to a significant increase in maternal morbidity and mortality. Furthermore, shortage of healthcare resources during this time can convert even routine obstetric complications into emergencies. Once a vulnerable population has experienced a disaster, the community can take many years to repair and that repair period can lead to further vulnerability. The disastrous consequences of natural disaster also affect
9660-551: The amount of microplastics on beaches surveyed following a typhoon in Hong Kong in 2018. A significant amount of plastic waste can be produced during disaster relief operations. Following the 2010 earthquake in Haiti , the generation of waste from relief operations was referred to as a "second disaster". The United States military reported that millions of water bottles and styrofoam food packages were distributed although there
9800-510: The boundary with the Yukon Territory . Mud volcanoes (mud domes) are formations created by geo-excreted liquids and gases, although several processes may cause such activity. The largest structures are 10 kilometres in diameter and reach 700 meters high. The material that is expelled in a volcanic eruption can be classified into three types: The concentrations of different volcanic gases can vary considerably from one volcano to
9940-431: The capability to capture and move ice, rocks, and trees. Avalanches occur in two general forms, or combinations thereof: slab avalanches made of tightly packed snow, triggered by a collapse of an underlying weak snow layer, and loose snow avalanches made of looser snow. After being set off, avalanches usually accelerate rapidly and grow in mass and volume as they capture more snow. If an avalanche moves fast enough, some of
10080-402: The case of Lassen Peak . Like stratovolcanoes, they can produce violent, explosive eruptions, but the lava generally does not flow far from the originating vent. Cryptodomes are formed when viscous lava is forced upward causing the surface to bulge. The 1980 eruption of Mount St. Helens was an example; lava beneath the surface of the mountain created an upward bulge, which later collapsed down
10220-434: The causes of a disaster and the distribution of political and financial responsibility in disaster risk reduction , disaster management , compensation, insurance and disaster prevention. Using natural to describe disasters misleads people to think the devastating results are inevitable, out of our control, and are simply part of a natural process. Hazards (earthquakes, hurricanes, pandemics, drought etc.) are inevitable, but
10360-418: The climate hazard flooding can combine with poor water quality. Climate scientists have pointed out that climate hazards affect different groups of people differently, depending on their climate change vulnerability : There are "factors that make people and groups vulnerable (e.g., poverty, uneven power structures, disadvantage and discrimination due to, for example, social location and the intersectionality or
10500-416: 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. A hazard is defined as "the potential occurrence of
10640-460: 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: 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,
10780-611: The country. As a result, many desalination plants were built for the first time ( see list ). In 2011, the State of Texas lived under a drought emergency declaration for the entire calendar year and suffered severe economic losses. The drought caused the Bastrop fires. Wildfires are large fires which often start in wildland areas. Common causes include lightning and drought but wildfires may also be started by human negligence or arson . They can spread to populated areas and thus be
10920-410: The damage is depends on how well people are prepared for disasters and how strong the buildings, roads, and other structures are. Scholars have been saying that the term natural disaster is unsuitable and should be abandoned. Instead, the simpler term disaster could be used. At the same time the type of hazard would be specified. A disaster happens when a natural or human-made hazard impacts
11060-469: The damage typically associated with storms, such as winds, hail and flooding, the lightning itself can damage buildings, ignite fires and kill by direct contact. Most deaths from lightning occur in the poorer countries of the Americas and Asia, where lightning is common and adobe mud brick housing provides little protection. Typhoon , cyclone , cyclonic storm and hurricane are different names for
11200-442: The earthquake is called the seismic focus . The point directly above the focus on the surface is called the epicenter . Earthquakes by themselves rarely kill people or wildlife – it is usually the secondary events that they trigger, such as building collapse, fires, tsunamis and volcanic eruptions, that cause death. Many of these can possibly be avoided by better construction, safety systems, early warning and planning. A sinkhole
11340-799: The enormous area they cover, and subsequent concealment under vegetation and glacial deposits, supervolcanoes can be difficult to identify in the geologic record without careful geologic mapping . Known examples include Yellowstone Caldera in Yellowstone National Park and Valles Caldera in New Mexico (both western United States); Lake Taupō in New Zealand; Lake Toba in Sumatra , Indonesia; and Ngorongoro Crater in Tanzania. Volcanoes that, though large, are not large enough to be called supervolcanoes, may also form calderas in
11480-445: The environment are often negatively impacted. Natural disasters (e.g. earthquakes, tsunamis, hurricanes) have the potential to generate a significant amount of waste within a short period. Waste management systems can be out of action or curtailed, often requiring considerable time and funding to restore. For example, the tsunami in Japan in 2011 produced huge amounts of debris: estimates of 5 million tonnes of waste were reported by
11620-411: 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
11760-628: The event that it significantly harms a community. 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 hazard is a natural phenomenon that might have a negative effect on humans and other animals , or the environment . Natural hazard events can be classified into two broad categories: geophysical and biological . Natural hazards can be provoked or affected by anthropogenic processes , e.g. land-use change , drainage and construction. There are 18 natural hazards included in
11900-439: 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
12040-438: 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
12180-555: The fact that fewer women knew how to swim. During and after a natural disaster, women are at increased risk of being affected by gender based violence and are increasingly vulnerable to sexual violence. Disrupted police enforcement, lax regulations, and displacement all contribute to increased risk of gender based violence and sexual assault. In addition to LGBT people and immigrants , women are also disproportionately victimized by religion-based scapegoating for natural disasters: fanatical religious leaders or adherents may claim that
12320-431: The flow is covered with angular, vesicle-poor blocks. Rhyolitic flows typically consist largely of obsidian . Tephra is made when magma inside the volcano is blown apart by the rapid expansion of hot volcanic gases. Magma commonly explodes as the gas dissolved in it comes out of solution as the pressure decreases when it flows to the surface . These violent explosions produce particles of material that can then fly from
12460-612: The food chain. Natural hazard A natural disaster is the very harmful impact on a society or community after a natural hazard event. Some examples of natural hazard events include avalanches , droughts , earthquakes , floods , heat waves , landslides , tropical cyclones , volcanic activity and wildfires . Additional natural hazards include blizzards , dust storms , firestorms , hails , ice storms , sinkholes , thunderstorms , tornadoes and tsunamis . A natural disaster can cause loss of life or damage property . It typically causes economic damage. How bad
12600-441: The form of a visible condensation funnel , the narrow end of which touches the Earth and is often encircled by a cloud of debris and dust . Tornadoes can occur one at a time, or can occur in large tornado outbreaks associated with supercells or in other large areas of thunderstorm development. Most tornadoes have wind speeds of less than 180 km/h (110 mph), are approximately 75 m (250 ft) across, and travel
12740-610: The formation of a submarine volcano off the coast of Mayotte . Subglacial volcanoes develop underneath ice caps . They are made up of lava plateaus capping extensive pillow lavas and palagonite . These volcanoes are also called table mountains, tuyas , or (in Iceland) mobergs. Very good examples of this type of volcano can be seen in Iceland and in British Columbia . The origin of the term comes from Tuya Butte , which
12880-585: The future. In an article justifying the re-classification of Alaska's Mount Edgecumbe volcano from "dormant" to "active", volcanologists at the Alaska Volcano Observatory pointed out that the term "dormant" in reference to volcanoes has been deprecated over the past few decades and that "[t]he term "dormant volcano" is so little used and undefined in modern volcanology that the Encyclopedia of Volcanoes (2000) does not contain it in
13020-466: The glossaries or index", however the USGS still widely employs the term. Previously a volcano was often considered to be extinct if there were no written records of its activity. Such a generalization is inconsistent with observation and deeper study, as has occurred recently with the unexpected eruption of the Chaitén volcano in 2008. Modern volcanic activity monitoring techniques, and improvements in
13160-406: 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). An example of the distinction between
13300-409: The immediate surroundings of a volcanic eruption is pyroclastic flows , consisting of a cloud of hot ash which builds up in the air above the volcano and rushes down the slopes when the eruption no longer supports the lifting of the gases. It is believed that Pompeii was destroyed by a pyroclastic flow. A lahar is a volcanic mudflow or landslide. The 1953 Tangiwai disaster was caused by a lahar, as
13440-408: The impact they have on society is not. Thus, the term natural disaster is unsuitable and should be abandoned in favor of the simpler term disaster , while also specifying the category (or type) of hazard. As of 2019, the countries with the highest share of disability-adjusted life years ( DALY ) lost due to natural disasters are Bahamas , Haiti , Zimbabwe and Armenia (probably mainly due to
13580-492: The interior of a continent and lead to rifting. Early stages of rifting are characterized by flood basalts and may progress to the point where a tectonic plate is completely split. A divergent plate boundary then develops between the two halves of the split plate. However, rifting often fails to completely split the continental lithosphere (such as in an aulacogen ), and failed rifts are characterized by volcanoes that erupt unusual alkali lava or carbonatites . Examples include
13720-410: The last 100 years, due to the increased development of countries, increased preparedness, better education, better methods, and aid from international organizations. Since the global population has grown over the same time period, the decrease in number of deaths per capita is larger, dropping to 6% of the original amount. The death rate from natural disasters is highest in developing countries due to
13860-406: The like. Some things can make natural disasters worse. Examples are inadequate building norms, marginalization of people and poor choices on land use planning . Many developing countries do not have proper disaster risk reduction systems. This makes them more vulnerable to natural disasters than high income countries . An adverse event only becomes a disaster if it occurs in an area with
14000-496: The lower quality of building construction, infrastructure, and medical facilities. Global economic losses due to extreme weather, climate and water events are increasing. Costs have increased sevenfold from the 1970s to the 2010s. Direct losses from disasters have averaged above US$ 330 billion annually between 2015 and 2021. Socio-economic factors have contributed to this trend of increasing losses, such as population growth and increased wealth. This shows that increased exposure
14140-525: The mental health of affected communities, often leading to post-traumatic symptoms. These increased emotional experiences can be supported through collective processing, leading to resilience and increased community engagement. Disasters stress government capacity, as the government tries to conduct routine as well as emergency operations. Some theorists of voting behavior propose that citizens update information about government effectiveness based on their response to disasters, which affects their vote choice in
14280-419: The mid-oceanic ridge is above sea level, volcanic islands are formed, such as Iceland . Subduction zones are places where two plates, usually an oceanic plate and a continental plate, collide. The oceanic plate subducts (dives beneath the continental plate), forming a deep ocean trench just offshore. In a process called flux melting , water released from the subducting plate lowers the melting temperature of
14420-551: The modelling of the factors that produce eruptions, have helped the understanding of why volcanoes may remain dormant for a long time, and then become unexpectedly active again. The potential for eruptions, and their style, depend mainly upon the state of the magma storage system under the volcano, the eruption trigger mechanism and its timescale. For example, the Yellowstone volcano has a repose/recharge period of around 700,000 years, and Toba of around 380,000 years. Vesuvius
14560-415: The most dangerous type, are very rare; four are known from the last million years , and about 60 historical VEI 8 eruptions have been identified in the geologic record over millions of years. A supervolcano can produce devastation on a continental scale, and severely cool global temperatures for many years after the eruption due to the huge volumes of sulfur and ash released into the atmosphere. Because of
14700-438: The mud volcano is actually a vent of an igneous volcano. Volcanic fissure vents are flat, linear fractures through which lava emerges. Shield volcanoes, so named for their broad, shield-like profiles, are formed by the eruption of low-viscosity lava that can flow a great distance from a vent. They generally do not explode catastrophically but are characterized by relatively gentle effusive eruptions . Since low-viscosity magma
14840-691: 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: 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
14980-502: 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. Tsunamis can be caused by geophysical hazards, such as in the 2004 Indian Ocean earthquake and tsunami . Although generally
15120-569: The next election. Indeed, some evidence, based on data from the United States, reveals that incumbent parties can lose votes if citizens perceives them as responsible for a poor disaster response or gain votes based on perceptions of well-executed relief work. The latter study also finds, however, that voters do not reward incumbent parties for disaster preparedness , which may end up affecting government incentives to invest in such preparedness. Landslides , also known as landslips, or rockslides, are several forms of mass wasting that may include
15260-452: The next. Water vapour is typically the most abundant volcanic gas, followed by carbon dioxide and sulfur dioxide . Other principal volcanic gases include hydrogen sulfide , hydrogen chloride , and hydrogen fluoride . A large number of minor and trace gases are also found in volcanic emissions, for example hydrogen , carbon monoxide , halocarbons , organic compounds, and volatile metal chlorides. The form and style of an eruption of
15400-876: The north side of the mountain. Cinder cones result from eruptions of mostly small pieces of scoria and pyroclastics (both resemble cinders, hence the name of this volcano type) that build up around the vent. These can be relatively short-lived eruptions that produce a cone-shaped hill perhaps 30 to 400 metres (100 to 1,300 ft) high. Most cinder cones erupt only once and some may be found in monogenetic volcanic fields that may include other features that form when magma comes into contact with water such as maar explosion craters and tuff rings . Cinder cones may form as flank vents on larger volcanoes, or occur on their own. Parícutin in Mexico and Sunset Crater in Arizona are examples of cinder cones. In New Mexico , Caja del Rio
15540-549: The ocean surface as new islands or floating pumice rafts . In May and June 2018, a multitude of seismic signals were detected by earthquake monitoring agencies all over the world. They took the form of unusual humming sounds, and some of the signals detected in November of that year had a duration of up to 20 minutes. An oceanographic research campaign in May 2019 showed that the previously mysterious humming noises were caused by
15680-420: The ocean surface, due to the rapid cooling effect and increased buoyancy in water (as compared to air), which often causes volcanic vents to form steep pillars on the ocean floor. Hydrothermal vents are common near these volcanoes, and some support peculiar ecosystems based on chemotrophs feeding on dissolved minerals. Over time, the formations created by submarine volcanoes may become so large that they break
15820-471: The ocean's surface. In the deep ocean basins, the tremendous weight of the water prevents the explosive release of steam and gases; however, submarine eruptions can be detected by hydrophones and by the discoloration of water because of volcanic gases . Pillow lava is a common eruptive product of submarine volcanoes and is characterized by thick sequences of discontinuous pillow-shaped masses which form underwater. Even large submarine eruptions may not disturb
15960-468: The one that destroyed the city of Saint-Pierre in Martinique in 1902. They are also steeper than shield volcanoes, with slopes of 30–35° compared to slopes of generally 5–10°, and their loose tephra are material for dangerous lahars . Large pieces of tephra are called volcanic bombs . Big bombs can measure more than 1.2 metres (4 ft) across and weigh several tons. A supervolcano is defined as
16100-658: The overlapping and compounding risks from ethnicity or racial discrimination, gender, age, or disability, etc.)". Biological hazards, also known as biohazards, originate in biological processes of living organisms and pose threats to the health of humans, the security of property, or the environment. Biological hazards include pathogenic microorganisms , such as viruses and bacteria , epidemics , pandemics , parasites , pests , animal attacks , venomous animals , biological toxins and foodborne illnesses . For example, naturally occurring bacteria such as Escherichia coli and Salmonella are well known pathogens , and
16240-425: The overlying mantle wedge, thus creating magma . This magma tends to be extremely viscous because of its high silica content, so it often does not reach the surface but cools and solidifies at depth . When it does reach the surface, however, a volcano is formed. Thus subduction zones are bordered by chains of volcanoes called volcanic arcs . Typical examples are the volcanoes in the Pacific Ring of Fire , such as
16380-639: The place of older, less effective chemicals. Laws, such as the Federal Food, Drug, and Cosmetic Act and the Toxic Substances Control Act in the US, require protection of human health and the environment for any new chemical introduced. In the US, the EPA regulates new chemicals that may have environmental impacts (i.e., pesticides or chemicals released during a manufacturing process), while
16520-619: The plume, and new volcanoes are created where the plate advances over the plume. The Hawaiian Islands are thought to have been formed in such a manner, as has the Snake River Plain , with the Yellowstone Caldera being part of the North American plate currently above the Yellowstone hotspot . However, the mantle plume hypothesis has been questioned. Sustained upwelling of hot mantle rock can develop under
16660-444: The possibility of failure associated with human technology (including emerging technologies ), which can also impact the economy , health and national security . For example, technological hazards can arise from the following events: A mechanical hazard is any hazard involving a machine or industrial process. Motor vehicles, aircraft, and air bags pose mechanical hazards. Compressed gases or liquids can also be considered
16800-549: 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
16940-531: The same phenomenon: a tropical storm that forms over an ocean. It is caused by evaporated water that comes off of the ocean and becomes a storm . It is characterized by strong winds, heavy rainfall and thunderstorms. The determining factor on which term is used is based on where the storm originates. In the Atlantic and Northeast Pacific, the term "hurricane" is used; in the Northwest Pacific, it
17080-435: The same time interval. Volcanoes vary greatly in their level of activity, with individual volcanic systems having an eruption recurrence ranging from several times a year to once in tens of thousands of years. Volcanoes are informally described as erupting , active , dormant , or extinct , but the definitions of these terms are not entirely uniform among volcanologists. The level of activity of most volcanoes falls upon
17220-492: The same way; they are often described as "caldera volcanoes". Submarine volcanoes are common features of the ocean floor. Volcanic activity during the Holocene Epoch has been documented at only 119 submarine volcanoes, but there may be more than one million geologically young submarine volcanoes on the ocean floor. In shallow water, active volcanoes disclose their presence by blasting steam and rocky debris high above
17360-516: The skin. The negative effects of other chemicals, such as alcohol and nicotine , have been well documented. Organohalogens are a family of synthetic organic molecules which all contain atoms of one of the halogens . Such materials include PCBs , Dioxins , DDT , Freon and many others. Although considered harmless when first produced, many of these compounds are now known to have profound physiological effects on many organisms including man. Many are also fat soluble and become concentrated through
17500-450: The snow may mix with the air, forming a powder snow avalanche . An earthquake is the result of a sudden release of energy in the Earth's crust that creates seismic waves . At the Earth's surface, earthquakes manifest themselves by vibration, shaking, and sometimes displacement of the ground. Earthquakes are caused by slippage within geological faults . The underground point of origin of
17640-622: The solidified erupted material that makes up the mantle of a volcano may be stripped away that its inner anatomy becomes apparent. Using the metaphor of biological anatomy , such a process is called "dissection". Cinder Hill , a feature of Mount Bird on Ross Island , Antarctica , is a prominent example of a dissected volcano. Volcanoes that were, on a geological timescale, recently active, such as for example Mount Kaimon in southern Kyūshū , Japan , tend to be undissected. Eruption styles are broadly divided into magmatic, phreatomagmatic, and phreatic eruptions. The intensity of explosive volcanism
17780-429: The specific climate variables necessary for their formation. 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
17920-406: The surrounding areas, and initially not seismically monitored before its unanticipated and catastrophic eruption of 1991. Two other examples of volcanoes that were once thought to be extinct, before springing back into eruptive activity were the long-dormant Soufrière Hills volcano on the island of Montserrat , thought to be extinct until activity resumed in 1995 (turning its capital Plymouth into
18060-434: The theory of plate tectonics. For example, some volcanoes are polygenetic with more than one period of activity during their history; other volcanoes that become extinct after erupting exactly once are monogenetic (meaning "one life") and such volcanoes are often grouped together in a geographical region. At the mid-ocean ridges , two tectonic plates diverge from one another as hot mantle rock creeps upwards beneath
18200-444: The thinned oceanic crust . The decrease of pressure in the rising mantle rock leads to adiabatic expansion and the partial melting of the rock, causing volcanism and creating new oceanic crust. Most divergent plate boundaries are at the bottom of the oceans, and so most volcanic activity on Earth is submarine, forming new seafloor . Black smokers (also known as deep sea vents) are evidence of this kind of volcanic activity. Where
18340-431: The underlying ductile mantle , and most volcanic activity on Earth takes place along plate boundaries, where plates are converging (and lithosphere is being destroyed) or are diverging (and new lithosphere is being created). During the development of geological theory, certain concepts that allowed the grouping of volcanoes in time, place, structure and composition have developed that ultimately have had to be explained in
18480-492: The volcano. Solid particles smaller than 2 mm in diameter ( sand-sized or smaller) are called volcanic ash. Tephra and other volcaniclastics (shattered volcanic material) make up more of the volume of many volcanoes than do lava flows. Volcaniclastics may have contributed as much as a third of all sedimentation in the geologic record. The production of large volumes of tephra is characteristic of explosive volcanism. Through natural processes, mainly erosion , so much of
18620-424: The volcanoes of the East African Rift . A volcano needs a reservoir of molten magma (e.g. a magma chamber), a conduit to allow magma to rise through the crust, and a vent to allow the magma to escape above the surface as lava. The erupted volcanic material (lava and tephra) that is deposited around the vent is known as a volcanic edifice , typically a volcanic cone or mountain. The most common perception of
18760-510: The volume of a body of water, such as a river or lake , becoming higher than usual, causing some of the water to escape its usual boundaries. While the size of a lake or other body of water will vary with seasonal changes in precipitation and snow melt, a flood is not considered significant unless the water covers land used by humans, such as a village, city or other inhabited area, roads or expanses of farmland. Severe storms, dust clouds and volcanic eruptions can generate lightning . Apart from
18900-522: The waste disposal industry, those living around sites used for waste disposal or landfill and the general environment surrounding such sites. There are different ways to group hazards by origin. The definition by UNDRR states: "Hazards may be natural, anthropogenic or socionatural in origin." The socionatural hazards are those that are "associated with a combination of natural and anthropogenic factors, including environmental degradation and climate change ". The term climate hazard or climatic hazard
19040-710: Was a moderate year. 45% were meteorological (storms), 36% were hydrological (floods), 12% were climatological (heat waves, cold waves, droughts, wildfires) and 7% were geophysical events (earthquakes and volcanic eruptions). Between 1980 and 2011 geophysical events accounted for 14% of all natural catastrophes. Developing countries often have ineffective communication systems as well as insufficient support for disaster risk reduction and emergency management . This makes them more vulnerable to natural disasters than high income countries . Natural hazards occur across different time scales as well as area scales. Tornadoes and flash floods are rapid onset events, meaning they occur with
19180-421: Was described by Roman writers as having been covered with gardens and vineyards before its unexpected eruption of 79 CE , which destroyed the towns of Herculaneum and Pompeii . Accordingly, it can sometimes be difficult to distinguish between an extinct volcano and a dormant (inactive) one. Long volcano dormancy is known to decrease awareness. Pinatubo was an inconspicuous volcano, unknown to most people in
19320-749: Was no operational waste management system. Over 700,000 plastic tarpaulins and 100,000 tents were required for emergency shelters. The increase in plastic waste, combined with poor disposal practices, resulted in open drainage channels being blocked, increasing the risk of disease . Conflicts can result in large-scale displacement of communities. People living under these conditions are often provided with minimal waste management facilities. Burn pits are widely used to dispose of mixed wastes, including plastics. Air pollution can lead to respiratory and other illnesses. For example, Sahrawi refugees have been living in five camps near Tindouf, Algeria for nearly 45 years. As waste collection services are underfunded and there
19460-475: Was the European Heat Wave of 2003 . The 2010 Northern Hemisphere summer resulted in severe heat waves which killed over 2,000 people. The heat caused hundreds of wildfires which led to widespread air pollution and burned thousands of square kilometers of forest. Well-known historical droughts include the 1997–2009 Millennium Drought in Australia which led to a water supply crisis across much of
19600-488: Was the 1985 Armero tragedy in which the town of Armero was buried and an estimated 23,000 people were killed. Volcanoes rated at 8 (the highest level) on the volcanic explosivity index are known as supervolcanoes . According to the Toba catastrophe theory , 75,000 to 80,000 years ago, a supervolcanic eruption at what is now Lake Toba in Sumatra reduced the human population to 10,000 or even 1,000 breeding pairs, creating
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