Threats & Hazards

Natural Hazards

A natural hazard is a threat of a naturally occurring event that will have a negative effect on people, the environment or a social economic system. Many natural hazards are interrelated, for an example, earthquakes can cause tsunamis and drought can lead directly to famine or population displacement.

These are some of the natural occurring hazards.

Avalanche – is a geophysical hazard a slide of a large snow (or rock) mass down a mountainside, caused when a build-up of snow is released down a slope, it is one of the major dangers faced in the mountains in winter. An avalanche is an example of a gravity current consisting of granular material. In an avalanche, lots of material or mixtures of different types of material fall or slide rapidly under the force of gravity. Avalanches are often classified by the composition of the flowing material.

Earthquake – a phenomenon that results from a sudden release of stored energy that radiates seismic waves. At the Earth’s surface, earthquakes may manifest themselves by a shaking or displacement of the ground and sometimes tsunamis. Most of the world’s earthquakes (90%, and 81% of the largest) take place in the 40,000-km-long, horseshoe-shaped zone called the circum-Pacific seismic belt, also known as the Pacific Ring of Fire, which for the most part bounds the Pacific Plate. Many earthquakes happen each day, few of which are large enough to cause significant damage.

Sinkholes – is localized depression in the surface topography, usually caused by the collapse of a subterranean structure, such as a cave. Although rare, large sinkholes that develop suddenly in populated areas can lead to the collapse of buildings and other structures.

Volcanic eruption – is the point in which a volcano is active and releases its power, and the eruptions come in many forms. They range from daily small eruptions which occur in places like Kilauea in Hawaii, to megacolossal eruptions (where the volcano expels at least 1,000 cubic kilometers of material)] from supervolcanoes like Lake Taupo (26,500 years ago) and Yellowstone Caldera. According to the Toba catastrophe theory, 70 to 75 thousand years ago, a super volcanic event at Lake Toba reduced the human population to 10,000 or even 1,000 breeding pairs, creating a bottleneck in human evolution. Some eruptions form pyroclastic flows, which are high-temperature clouds of ash and steam that can trial down mountainsides at speed exceeding an airliner.

A lahar is a type of natural disaster closely related to a volcanic eruption, and involves a large amount of material originating from an eruption of a glaciated volcano, including mud from the melted ice, rock, and ash sliding down the side of the volcano at a rapid pace. These flows can destroy entire towns in seconds and kill thousands of people.

Blizzard – A blizzard is a severe winter storm icy and windy conditions characterized by low temperatures, strong winds, and heavy snow.

Drought – is an extended period when a region notes a deficiency in its water supply whether surface or underground water. A drought can last for months or years, or may be declared after as few as 15 days. Generally, this occurs when a region receives consistently below average precipitation. It can have a substantial impact on the ecosystem and agriculture of the affected region. Although droughts can persist for several years, even a short, intense drought can cause significant damage and harm to the local economy.

Hailstorm – is a natural hazard where a thunderstorm produces numerous hailstones which damage the location in which they fall. Hailstorms can be especially devastating to farm fields, ruining crops and damaging equipment.

Heat Wave – is a hazard characterized by heat which is considered extreme and unusual in the area in which it occurs. Heat waves are rare and require specific combinations of weather events to take place, and may include temperature inversions, katabatic winds, or other phenomena. There is potential for longer term events causing global warming, including stadial events (the opposite to glacial ‘ice age’ events), or through human induced climatic warming.

Cyclonic Storms – Hurricane, tropical cyclone, and typhoon are different names for the same phenomenon: a cyclonic storm system that forms over the oceans. It is caused by evaporated water that comes off of the ocean and becomes a storm. The Coriolis Effect causes the storms to spin, and a hurricane is declared when this spinning mass of storms attains a wind speed greater than 74 mph (119 km/h). Hurricane is used for these phenomena in the Atlantic and eastern Pacific Oceans, tropical cyclone in the Indian, typhoon in the western Pacific.

Ice Storm – An ice storm is a particular weather event in which precipitation falls as ice, due to atmosphere conditions.

Tornado – is a natural disaster resulting from a thunderstorm. Tornadoes are violent, rotating columns of air which can blow at speeds between 50 mph (80 km/h) and 300 mph (480 km/h), and possibly higher. 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. Waterspouts are tornadoes occurring over tropical waters in light rain conditions.

Geomagnetic Storm – Geomagnetic storms can disrupt or damage technological infrastructure, and disorient species with magnetoception.

Climate Change – is a long-term hazard which can increase or decrease the risk of other weather hazards, and also directly endangers property due to sea level rise and biological organisms due to habitat destruction.

Landslides – is a geological phenomenon which includes a wide range of ground movements, such as rock falls, deep failure of slopes and shallow debris flows, which can occur in offshore, coastal and onshore environments. Although the action of gravity is the primary driving force for a landslide to occur, there are other contributing factors affecting the original slope stability. Typically, pre-conditional factors build up specific sub-surface conditions that make the area/slope prone to failure, whereas the actual landslide often requires a trigger before being released.

Debris Flow – are geological phenomena in which water-laden masses of soil and fragmented rock rush down mountainsides, funnel into stream channels, entrain objects in their paths, and form thick, muddy deposits on valley floors. They generally have bulk densities comparable to those of rock avalanches and other types of landslides (roughly 2000 kilograms per cubic meter), but owing to widespread sediment liquefaction caused by high pore-fluid pressures, they can flow almost as fluidly as water. Debris flows descending steep channels commonly attain speeds that surpass 10 meters per second (more than 20 miles per hour), although some large flows can reach speeds that are much greater. Debris flows with volumes ranging up to about 100,000 cubic meters occur frequently in mountainous regions worldwide. The largest prehistoric flows have had volumes exceeding 1 billion cubic meters (i.e., 1 cubic kilometer). As a result of their high sediment concentrations and mobility, debris flows can be very destructive. Great debris-flow disasters of the twentieth century involved more than 20,000 fatalities in Armero, Colombia in 1985 and in Vargas State, Venezuela in 1999.

Thunderstorms – A thunderstorm, also known as an electrical storm, a lightning storm, thundershower or simply a storm, is a form of turbulent weather characterized by the presence of lightning and its acoustic effect on the Earth’s atmosphere known as thunder. The meteorologically assigned cloud type associated with the thunderstorm is the cumulonimbus. Thunderstorms are usually accompanied by strong winds, heavy rain and sometimes snow, sleet, hail, or no precipitation at all. Those that cause hail to fall are called hailstorms. Thunderstorms may line up in a series or rainband, known as a squall line. Strong or severe thunderstorms may rotate, known as supercells. While most thunderstorms move with the mean wind flow through the layer of the troposphere that they occupy, vertical wind shear causes a deviation in their course at a right angle to the wind shear direction.

Lighting – is the deliberate use of light to achieve a practical or aesthetic effect. Lighting includes the use of both artificial light sources like lamps and light fixtures, as well as natural illumination by capturing daylight. Daylighting (using windows, skylights, or light shelves) is sometimes used as the main source of light during daytime in buildings. This can save energy in place of using artificial lighting, which represents a major component of energy consumption in buildings. Proper lighting can enhance task performance, improve the appearance of an area, or have positive psychological effects on occupants.

Tsunamis – is a series of water waves caused by the displacement of a large volume of a body of water, generally an ocean or a large lake. Earthquakes, volcanic eruptions and other underwater explosions (including detonations of underwater nuclear devices), landslides, glacier calvings, meteorite impacts and other disturbances above or below water all have the potential to generate a tsunami.

Wildfires – is an uncontrolled fire in an area of combustible vegetation that occurs in the countryside or a wilderness area. Other names such as brush fire, bushfire, forest fire, desert fire, grass fire, hill fire, peat fire, vegetation fire, and veldfire may be used to describe the same phenomenon depending on the type of vegetation being burned. A wildfire differs from other fires by its extensive size, the speed at which it can spread out from its original source, its potential to change direction unexpectedly, and its ability to jump gaps such as roads, rivers and fire breaks. Wildfires are characterized in terms of the cause of ignition, their physical properties such as speed of propagation, the combustible material present, and the effect of weather on the fire.

Subsidence – is the motion of a surface (usually, the Earth’s surface) as it shifts downward relative to a datum such as sea-level. The opposite of subsidence is uplift, which results in an increase in elevation. Ground subsidence is of concern to geologists, geotechnical engineers and surveyors.

Famine – is a widespread scarcity of food, caused by several factors including crop failure, population unbalance, or government policies. This phenomenon is usually accompanied or followed by regional malnutrition, starvation, epidemic, and increased mortality. Nearly every continent in the world has experienced a period of famine throughout history. Some countries, particularly in sub-Sahara Africa, continue to have extreme cases of famine.

Foreign Animal Disease – is a disease that is not found in the United States. These diseases may have been in the United States at one point, but have been eradicated, or have never been present in this country. The foreign animal diseases of greatest concern could cause significant illness and/or death in animals or economic devastation.

Extreme Heat – High temperature weather exceeding the average and of several weeks duration. Extreme heat is a dangerous situation that can bring on health emergencies in susceptible people.

Duststorms/standstorms – A severe windstorm that sweeps clouds of dust across an extensive area, especially in an arid region.

Asteroid Impacts – An impact event is a collision between celestial objects causing measurable effects. Impact events have physical consequences and have been found to regularly occur, though typically relatively small and involving asteroids, comets or meteoroids. When terrestrial planets such as Earth are involved in large impact events, there can be physical and biospheric consequences, though atmospheric entry mitigates most surface impacts. Impact events have played a significant role in the evolution of the Solar System since the beginning and in the origins and evolution of the Earth. Major impact events have significantly shaped Earth’s history, have been implicated in the formation of the Earth–Moon system, the evolutionary history of life, the origin of water on Earth and several mass extinctions. Impact craters are the result of impact events on solid objects and as the dominant landforms on many of the System’s solid objects and provide the most solid evidence of prehistoric events. Notable impact events include the Late Heavy Bombardment, which occurred early in history of the Earth–Moon system and the Chicxulub impact, 65 million years ago, believed to be the cause of the Cretaceous–Paleogene extinction event.

Man-Made Hazards & Threats

Disasters also can be caused by humans. Hazardous materials emergencies include chemical spills and groundwater contamination. Workplace fires are more common and can cause significant property damage and loss of life. Communities are also vulnerable to threats posed by extremist groups who use violence against both people and property.

Hazardous Materials – is defined as any substance or material could adversely affect the safety of the public, handlers or carriers during transportation.

Power Service Disruption & Blackout – a period of time when there is no electricity in a building or area.

Nuclear Power Plant Failure – Nuclear reactors can fail in a variety of ways. Should the instability of the nuclear material generate unexpected behavior, it may result in an uncontrolled power excursion. Normally, the cooling system in a reactor is designed to be able to handle the excess heat this causes; however, should the reactor also experience a loss-of-coolant accident, then the fuel may melt or cause the vessel in which it is contained to overheat and melt. This event is called a nuclear meltdown.

After shutting down, for some time the reactor still needs external energy to power its cooling systems. Normally this energy is provided by the power grid to which that plant is connected, or by emergency diesel generators. Failure to provide power for the cooling systems.

Radiological Emergencies – is an emergency in which there is, or is perceived to be, a hazard due to radiation exposure from a source. As sources of radiation are used in various fields, including industry, medicine and research, radiological emergencies may occur anywhere.

Chemical Threat and Weapons – A chemical attack is the deliberate release of a toxic gas, liquid, or solid that can poison people and the environment. Possible signs of a chemical attack are:

  • Many people suffering from watery eyes, twitching, choking, having trouble breathing or losing coordination.
  • Many sick or dead birds, fish, or other small animals are also a cause for suspicion.

Bioterrorism – is terrorism involving the intentional release or dissemination of biological agents. These agents are bacteria, viruses, or toxins, and may be in a naturally occurring or a human-modified form. For the use of this method in warfare, see biological warfare.

Cyber attacks – is deliberate exploitation of computer systems, technology-dependent enterprises and networks. Cyberattacks use malicious code to alter computer code, logic or data, resulting in disruptive consequences that can compromise data and lead to cybercrimes, such as information and identity theft.

Civil Unrest – also known as civil unrest or civil strife, is a broad term that is typically used by law enforcement to describe one or more forms of unrest caused by a group of people.  Civil disturbance is typically a symptom of, and a form of protest against, major socio-political problems; the severity of the action coincides with public expression(s) of displeasure. Examples of civil disorder include, but are not necessarily limited to: illegal parades; sit-ins and other forms of obstructions; riots; sabotage; and other forms of crime. It is intended to be a demonstration to the public and the government, but can escalate into general chaos.

Economic Collapse – A complete breakdown of a national, regional or territorial economy. An economic collapse is essentially a severe version of an economic depression, where an economy is in complete distress for months, years or possibly even decades.

A total economic collapse is characterized by economic depression, civil unrest and highly increased poverty levels. Hyperinflation, stagflation and financial-market crashes can all be causes. Government intervention is usually necessary to bring an economy back from collapse, but can often be slow to remedy the problem.

Electro Magnetic Pulse – (EMP), also sometimes called a transient disturbance, is a short burst of electromagnetic energy. It may occur in the form of a radiated, electric or magnetic field or conducted electrical current depending on the source. Electromagnetic pulse is commonly abbreviated EMP, pronounced by saying the letters separately (E-M-P).

EMP is generally damaging to electronic equipment, and its management is an important branch of electromagnetic compatibility (EMC) engineering. At higher energy levels, an EMP event such as a lightning strike can cause more widespread damage to aircraft structures and other objects.

The damaging effects of high-energy EMP have been used to create EMP weapons, both nuclear and non-nuclear. These weapons, both real and fictional, have gained traction in popular culture.

Terrorist Attack – a surprise attack involving the deliberate use of violence against civilians in the hope of attaining political or religious aims.

Nuclear Blast – is a man-made explosion that occurs as a result of the rapid release of energy from an intentionally generated high-speed nuclear reaction. The driving reaction may be nuclear fission, nuclear fusion or a multistage cascading combination of the two, though to date all fusion based weapons have used a fission device to initiate fusion, and a pure fusion weapon remains a hypothetical device.



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