   #copyright

Natural disaster

2007 Schools Wikipedia Selection. Related subjects: Geology and geophysics

   Mount Pinatubo eruption, 1991
   Enlarge
   Mount Pinatubo eruption, 1991

   A natural disaster is the consequence of the combination of a natural
   hazard (a physical event e.g. volcanic eruption, earthquake, landslide)
   and human activities. Human vulnerability, caused by the lack of
   appropriate emergency management, leads to financial, structural, and
   human losses. The resulting loss depend on the capacity of the
   population to support or resist the disaster, their resilience . This
   understanding is concentrated in the formulation: "disasters occur when
   hazards meet vulnerability" . A natural hazard will hence never result
   in a natural disaster in areas without vulnerability, e.g. strong
   earthquakes in uninhabited areas. The term natural has consequently
   been disputed because the events simply are not hazards or disasters
   without human involvement . The degree of potential loss can also
   depend on the nature of the hazard itself, ranging from wildfires,
   which threaten individual buildings, to impact events, which have the
   potential to end civilization.

Natural hazards

   A natural hazard is an event that has an effect on people resulting
   from the natural processes in the environment. Some natural hazards are
   related - earthquakes can result in tsunamis, drought can lead directly
   to famine and disease, and so on.

Earth

   Avalanche

   Avalanche on the backside (East) of Mt. Timpanogos, Utah at Aspen Grove
   trail
   Enlarge
   Avalanche on the backside (East) of Mt. Timpanogos, Utah at Aspen Grove
   trail

          An avalanche is a geophysical hazard involving a slide of a
          large snow (or rock) mass down a mountainside, caused when a
          buildup 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 what they are made of.
          Notable avalanches include:

          + The 1970 Ancash earthquake
          + The 1954 Blons avalanches
          + The 1999 Galtür Avalanche
          + The 2002 Kolka-Karmadon rock ice slide
          + The 1910 Wellington avalanche

   Earthquake

          An earthquake is a phenomenon that results from and is powered
          by the 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. 90% of all earthquakes - and 81% of the
          largest - occur around the 40,000km long Pacific Ring of Fire,
          which roughly bounds the Pacific Plate. Many earthquakes happen
          each day, vary few of which are large enough to cause
          significant damage. Some of the most significant earthquakes in
          recent times include:

          + The 2004 Indian Ocean earthquake, one of the largest
            earthquakes in recorded history, registering a moment
            magnitude of 9.1-9.3. The huge tsunamis triggered by this
            earthquake cost the lives of at least 229,000 people.
          + The 2005 Kashmir earthquake, which cost 79,000 lives in
            Pakistan.
          + The 7.7 magnitude July 2006 Java earthquake, which also
            triggered tsunamis.

   A Sumatran village, devastated by the tsunami that followed the 2004
   Indian Ocean earthquake
   Enlarge
   A Sumatran village, devastated by the tsunami that followed the 2004
   Indian Ocean earthquake

   Lahar
          A Lahar is a type of natural disaster closely related to a
          volcanic eruption, and involves a large amount of material,
          including mud, 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. The Tangiwai disaster is
          an excellent example, as is the one which killed an estimated
          23,000 people in Armero, Colombia, during the 1985 eruption of
          Nevado del Ruiz.

   Landslides and Mudflows
          A landslide is a disaster closely related to an avalanche, but
          instead of occurring with snow, it occurs involving actual
          elements of the ground, including rocks, trees, parts of houses,
          and anything else which may happen to be swept up. Landslides
          can be caused by earthquakes, volcanic eruptions, or general
          instability in the surrounding land. Mudslides, or mud flows,
          are a special case of landslides, in which heavy rainfall causes
          loose soil on steep terrain to collapse and slide downwards (see
          also Lahar); these occur with some regularity in parts of
          California after periods of heavy rain.

   Sinkholes
          A 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.

   Supervolcano
          A supervolcano is an eruption which is thousands of times larger
          than a normal eruption. If a volcano expels at least 1,000 cubic
          kilometers of material, it is declared a supervolcano. The last
          eruption of this magnitude occurred over 75,000 years ago at
          Lake Toba. If such an eruption were to occur today, a wholesale
          general die-off of both animals and humans would occur, as well
          as a significant short-term climate change. The Yellowstone
          Caldera has the potential to become a supervolcano within the
          near geological future.

Water

   Flood

   The Limpopo River, in southern Mozambique, during the 2000 Mozambique
   flood
   Enlarge
   The Limpopo River, in southern Mozambique, during the 2000 Mozambique
   flood

          Prolonged rainfall from a storm, including thunderstorms, rapid
          melting of large amounts of snow, or rivers which swell from
          excess precipitation upstream and cause widespread damage to
          areas downstream, or less frequently the bursting of man-made
          dams or levees.

          + The Huang He (Yellow River) in China floods particularly
            often. The Great Flood of 1931 caused between 800,000 and
            4,000,000 deaths.
          + The Great Flood of 1993 was one of the most costly floods in
            US history.
          + The 1998 Yangtze River Floods, also in China, left 14 million
            people homeless.
          + The 2000 Mozambique flood covered much of the country for
            three weeks, resulting in thousands of deaths, and leaving the
            country devastated for years afterward.

          Tropical storms can result in extensive flooding, as happened
          with:

          + Typhoon Nina, striking China in 1975,
          + Tropical Storm Allison, which struck Houston, Texas in 2001
            and
          + Hurricane Katrina, which left most of New Orleans under water
            in 2005.

   Limnic Eruption

          Also referred to as a lake overturn, a limnic eruption is a rare
          type of natural disaster in which CO[2] 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 CO[2] displaces water. Scientists
          believe landslides, volcanic activity, or explosions 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 Monoun caused
            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.

   Maelstrom

          A large tidal whirlpool. The largest known maelstrom is
          Moskstraumen off the Lofoten islands in Norway. Powerful
          whirlpools have killed unlucky seafarers, but their power tends
          to be exaggerated in fiction. Maelstroms can reach speeds of
          20-40km/h.

   The tsunami caused by the December 26, 2004 earthquake strikes Ao Nang,
   Thailand.
   Enlarge
   The tsunami caused by the December 26, 2004 earthquake strikes Ao Nang,
   Thailand.

   Tsunami

          A tsunami is a giant wave of water which rolls into the shore of
          an area with a height of over 15 m (50 ft). It comes from
          Japanese words "津波" meaning harbour and wave. Tsunami can be
          caused by undersea earthquakes as in the 2004 Indian Ocean
          Earthquake, or by landslides such as the one which occurred at
          Lituya Bay, Alaska. The tsunami generated by the 2004 Indian
          Ocean Earthquake currently ranks as the deadliest tsunami in
          recorded history. The highest Tsunami ever recorded was
          estimated to be 85m (278 ft.) high. It appeared on April 24th,
          1771, off Ishigaki Island, Japan.

   Megatsunami
          Mega tsunami is an informal term used to describe very large
          tsunamis. They are a highly local effect, either occurring on
          shores extremely close to the origin of a tsunami, or in deep,
          narrow inlets. The largest waves are caused by a very large
          landslide, such as a collapsing island, into a body of water.
          They can potentially reach 20 km inland in low-lying regions.

Storms and weather

   Young steer after a blizzard, March 1966
   Enlarge
   Young steer after a blizzard, March 1966

   Blizzard

          A severe winter storm condition characterized by low
          temperatures, strong winds, and heavy blowing snow. Significant
          blizzards in the United States include:

          + The Great Blizzard of 1888
          + The Schoolhouse Blizzard earlier the same year
          + The Armistice Day Blizzard in 1940
          + The Storm of the Century in 1993

   Drought

          An abnormally dry period when there is not enough water to
          support agricultural, urban or environmental water needs.
          Extended droughts can result in deaths by starvation or disease,
          and can result in wildfires. Well-known historical droughts
          include:

          + 1900 India, killing between 250,000 and 3.25 million.
          + 1921- 22, Soviet Union, in which 250,000 to 5 million perished
            from starvation due to drought.
          + 1928- 30, northwest China, resulting in over 3 million deaths
            by famine.
          + 1936 and 1941, Sichuan Province, China, resulting in 5 million
            and 2.5 million deaths respectively.

          As of 2006, western Australia has been under drought conditions
          for five to ten years. The drought is beginning to affect urban
          populations for the first time. Also in 2006, Sichuan Province,
          China experienced its worst drought in modern times, with nearly
          8 million people and over 7 million cattle facing water
          shortages.

          Scientists warn that global warming may result in more extensive
          drought in coming years.

   Hailstorm

          A hailstorm is a natural disaster 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. A particularly damaging
          hailstorm hit Munich, Germany on August 31, 1986, felling
          thousands of trees and causing millions of dollars in insurance
          claims.

   Heat wave

          A heat wave is a disaster 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. The worst heat wave in
          recent history was the European Heat Wave of 2003.

   Hurricane Katrina
   Enlarge
   Hurricane Katrina

   Hurricanes, Tropical cyclones, and Typhoons

          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. Hurricane is
          used for these phenomena in the Atlantic Ocean, tropical cyclone
          in the Indian, typhoon in the eastern Pacific. 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.

   Ice age
          An ice age is a geologic period, but could also be viewed in the
          light of a catastrophic natural disaster, since in an ice age,
          the climate all over the world would change and places which
          were once considered habitable would then be too cold to
          permanently inhabit. A side effect of an ice age could possibly
          be a famine, caused by a worldwide drought.

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

   Tornado
          A tornado is a natural disaster resulting from a thunderstorm.
          Tornadoes are violent, rotating columns of air which can blow at
          speeds between 50 and 300 mph, and possibly higher. Tornadoes
          can occur one at a time, or can occur in large tornado outbreaks
          along squall lines or in other large areas of thunderstorm
          development.

Fire

   Wildfire

          An uncontrolled fire burning in wildland areas. Common causes
          include lightning and drought but wildfires may also be started
          by human negligence or arson. They can be a threat to those in
          rural areas and also wildlife. Wildfires can also produce ember
          attacks, where floating embers set fire to buildings at a
          distance from the fire itself.

Health and disease

   Epidemic

   The A H5N1 virus, which cases Avian flu
   Enlarge
   The A H5N1 virus, which cases Avian flu

          An outbreak of a contractible disease that spreads at a rapid
          rate through a human population. A pandemic is an epidemic whose
          spread is global. There have been many epidemics throughout
          history. In the last hundred years, significant pandemics
          include:

          + The 1918 Spanish flu pandemic, killing an estimated 50 million
            people worldwide
          + The 1957- 58 Asian flu pandemic, which killed an estimated 1
            million people
          + The 1968- 69 Hong Kong flu pandemic
          + The 2002- 3 SARS pandemic
          + The AIDS epidemic, beginning in 1959

          Other diseases that spread more slowly, but are still considered
          to be global health emergencies by the WHO include:

          + XDR TB, a strain of tuberculosis that is resistant to all
            known treatments
          + Malaria, which kills an estimated 1.5 million people each year
          + Ebola hemorrhagic fever, which has claimed hundreds of victim
            in Africa in several outbreaks

   Famine

          A social and economic crisis that is commonly accompanied by
          widespread malnutrition, starvation, epidemic disease and
          increased mortality. Although some famines occur - or are
          aggravated - by natural factors, it can and often is a result of
          economic or military policy that deprives people of the food
          that they require to survive.

          In modern times, famine has hit Sub-Saharan Africa the hardest,
          although the number of victims of modern famines is much smaller
          than the number of people killed by the Asian famines of the
          20th century.

Space

   Impact event
          An impact event is a natural disaster in which an
          extraterrestrial piece of rock or other material collides with
          the Earth. The exact consequences of a direct Earth impact would
          vary greatly with size of the colliding object, although in
          cases of medium to large impacts short-term climate change and a
          general failure of agriculture. An example would be the Tunguska
          event.

   Solar flare
          A solar flare is a phenomenon where the sun suddenly releases a
          great amount of solar radiation, much more than normal. It is
          theorized that these releases of radiation could cause a
          widespread failure of communications technology across the
          globe. The exact implications of such a failure are unknown.
          Further studies are being carried out. Some known solar flares
          include:

          + An X20 event on August 16, 1989
          + A similar flare on April 2, 2001
          + The most powerful flare ever recorded, on November 4, 2003,
            estimated at between X40 and X45
          + The most powerful flare in the past 500 years is believed to
            have occurred in September 1859

International campaigns

   In 2000, the United Nations launched the International Early Warning
   Programme to address the underlying causes of vulnerability and to
   build disaster-resilient communities by promoting increased awareness
   of the importance of disaster reduction as an integral component of
   sustainable development, with the goal of reducing human, social,
   economic and environmental losses due to hazards of all kinds (UN/ISDR,
   2000).
   Retrieved from " http://en.wikipedia.org/wiki/Natural_disaster"
   This reference article is mainly selected from the English Wikipedia
   with only minor checks and changes (see www.wikipedia.org for details
   of authors and sources) and is available under the GNU Free
   Documentation License. See also our Disclaimer.
