Natural disaster

From Wikipedia, the free encyclopedia Jump to navigation Jump to search For other uses, see Natural disaster (disambiguation). Global multihazard proportional economic loss by natural distasters as cyclones, droughts, earthquakes, floods, landslides and vulcanoes A blizzard in Maryland in 2009 Global death from natural disasters A rope tornado in its dissipating stage, Tecumseh, Oklahoma. Global damage cost from natural disasters A daytime wildfire in California. 1755 copper engraving depicting Lisbon in ruins and in flames after the 1755 Lisbon earthquake. A tsunami overwhelms the ships in the harbor.

A natural disaster is a major adverse event resulting from natural processes of the Earth; examples include floods, hurricanes, tornadoes, volcanic eruptions, earthquakes, tsunamis, storms, and other geologic processes. A natural disaster can cause loss of life or damage property, and typically leaves some economic damage in its wake, the severity of which depends on the affected population's resilience and on the infrastructure available.

An adverse event will not rise to the level of a disaster if it occurs in an area without vulnerable population. In a vulnerable area, however, such as Nepal during the 2015 earthquake, an adverse event can have disastrous consequences and leave lasting damage, which can take years to repair.

Geological disasters

Avalanches and landslides

Main articles: Landslide and Avalanche

See also: List of landslides and List of avalanches A landslide in San Clemente, California in 1966

A landslide is described as an outward and downward slope movement of an abundance of slope-forming materials including rock, soil, artificial materials, or a combination of these.

During World War I, an estimated 40,000 to 80,000 soldiers died as a result of avalanchesduring the mountain campaign in the Alps at the Austrian-Italian front. Many of the avalanches were caused by artillery fire.

Earthquakes

Main article: Earthquake

See also: Lists of earthquakes Global Number of deaths from earthquake (1960-2017) Global number of recorded earthquake events

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 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.

Sinkholes

Main article: Sinkhole

See also: List of sinkholes The Red Lake in Croatia

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. For example, the 2010 Guatemala City sinkhole, which killed fifteen people, was caused when heavy rain from Tropical Storm Agatha, diverted by leaking pipes into a pumicebedrock, led to the sudden collapse of the ground beneath a factory building.

Volcanic eruptions

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 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 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 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 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.

Hydrological disasters

The Limpopo River during the 2000 Mozambique flood

A hydrological disaster is a violent, sudden and destructive change either in the quality of Earth's water or in the distribution or movement of water on land below the surface or in the atmosphere.

Floods

Main article: Flood

Tsunami

Main article: Tsunami

Limnic eruptions

Main article: Limnic eruption

A limnic eruption, also known as a lake overturn, occurs when a gas, usually CO₂, suddenly erupts from deep lake water, posing the threat of suffocating wildlife, livestock and humans. Such an eruption may also cause tsunamis in the lake as the rising gas displaces water. Scientists believe that landslides, explosions or volcanic activity can trigger such an eruption. To date, only two limnic eruptions have been observed and recorded. In 1984, in Cameroon, a limnic eruption in Lake Monouncaused the deaths of 37 nearby residents; at nearby Lake Nyos in 1986, a much larger eruption killed between 1,700 and 1,800 people by asphyxiation.

Whirlpool

I whirlpool is the type of natural phenomena The forms under the sea rivers and lakes which can be dangerous enough to sing boats ships it can also suck in submarines in marine life

Meteorological disasters

Young steer after a blizzard in South Dakota, March 1966

Main article: Meteorological disasters

Tropical cyclone

Typhoon, cyclone, cyclonic storm and hurricane are different names for the same phenomenon: a tropical storm that forms over an ocean. 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 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 a consequence of human-induced climate change.

Blizzards

Main article: Blizzard

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 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 2008 Afghanistan blizzard and the 1972 Iran blizzard were also significant events. The 1993 Superstorm originated in 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.

Hailstorms

Main article: Hail

Hailstorms are precipitation in the form of ice that does not melt before it hits the ground. Hailstones usually measure between 5 millimetres (0.2 inches) and 15 centimetres (6 inches) in diameter. A particularly damaging hailstorm hit Munich, Germany, on July 12, 1984, causing about $2 billion in insurance claims.

Ice storms

Main article: Ice storm

An ice storm is a type of winter storm characterized by freezing rain. The U.S. National Weather Service defines an ice storm as a storm which results in the accumulation of at least 0.25-inch (6.4 mm) of ice on exposed surfaces.

Cold waves

Main article: Cold wave

A cold wave, known in some regions as a cold snap or cold spell, is a weather phenomenon that is distinguished by a cooling of the air. Specifically, as used by the U.S. National Weather Service, a cold wave is a rapid fall in temperature within a 24-hour period, requiring substantially increased protection to agriculture, industry, commerce and social activities. The precise criterion for a cold wave is determined by the rate at which the temperature falls and the minimum to which it falls. This minimum temperature is dependent on the geographical region and time of year.

Heat waves

Main article: Heat wave

Droughts

Main article: Drought

Thunderstorms

Main article: Thunderstorm

Severe storms, dust clouds and volcanic eruptions can generate lightning. Apart from 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. Especially deadly lightning incidents include a 2007 strike in Ushari Dara, a remote mountain village in northwestern Pakistan, that killed 30 people; the crash of LANSA Flight 508 which killed 91 people; and a fuel explosion in Dronka, Egypt, caused by lightning in 1994 which killed 469 people. 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. A large hailstone, about 6 cm (2.4 in) in diameter

Tornadoes

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 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. Most tornadoes have wind speeds of less than 110 miles per hour (177 km/h), are approximately 250 feet (80 m) across, and travel a few miles (several kilometers) before dissipating. The most extreme tornadoes can attain wind speeds of more than 300 mph (480 km/h), stretch more than two miles (3 km) across, and stay on the ground for dozens of miles (perhaps more than 100 km).

Wildfires

Main article: wildfire

Space disasters

Fallen trees caused by the Tunguska meteoroid of the Tunguska event in June 1908.

Impact events and airburst

Main article: Impact event

Asteroids that impact the Earth have led to several major extinction events, including one which created the Chicxulub crater 64.9 million years ago and is associated with the extinction of the dinosaurs. Scientists estimate that the likelihood of death for a human from a global impact event is comparable to the probability of death from an airliner crash.

No human death has been definitively attributed to an impact event, but the 1490 Ch'ing-yang event in which over 10,000 people may have died has been linked to a meteor shower. Even asteroids and comets that burn up in the atmosphere can cause significant destruction on the ground due to the air burstexplosion; notable air bursts include the Tunguska event in June 1908, which devastated large areas of Siberian countryside, and the Chelyabinsk meteor on 15 February 2013, which caused widespread property damage in the city of Chelyabinsk and injured 1,491 people.

Solar flare

Main article: Solar flare

A solar flare is a phenomenon in which the Sun suddenly releases a much larger amount of solar radiation than normal. Solar flares are unlikely to cause any direct human injury but can destroy electrical equipment. The potential of solar storms to cause disaster was seen during the 1859 Carrington event, which disrupted the telegraph network, and the March 1989 geomagnetic storm which blacked out Quebec. Some major known solar flares include the X20 event on August 16, 1989, and a similar flare on April 2, 2001. The most powerful flare ever recorded occurred on November 4, 2003 (estimated at between X40 and X45).

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