Natural disasters

EARTHQUAKES
 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. The vibrations may vary in
magnitude. Earthquakes are caused mostly by slippage within
geological faults, but also by other events such as volcanic activity,
landslides, mine blasts, and nuclear tests. The underground point of
origin of the earthquake is called the 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 that are actually the human disaster.

Volcanic eruptions
• Volcanoes can cause widespread destruction and consequent disaster in
several ways. The effects include the volcanic eruption itself that may
cause harm following the explosion of the volcano or the fall of rock.
Second, lava may be produced during the eruption of a volcano. As it
leaves the volcano, the lava destroys many buildings, plants and animals
it encounters. Third, volcanic ash generally meaning the cooled ash - may
form a cloud, and settle thickly in nearby locations. When mixed with
water this forms a concrete-like material. In sufficient quantity ash may
cause roofs to collapse under its weight but even small quantities will
harm humans if inhaled. Since the ash has the consistency of ground glass
it causes abrasion damage to moving parts such as engines. The main
killer of humans in the immediate surroundings of a volcanic eruption is
the pyroclastic flows, which consist of a cloud of hot volcanic 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.

Floods
• A flood is an overflow of water that "submerges"
land.[11] The EU Floods Directive defines a flood as a
temporary covering by water of land not normally
covered by water.[12] In the sense of "flowing water",
the word may also be applied to the inflow of the tides.
Flooding may result from the volume of water within a
body of water, such as a river or lake, which overflows
causing the result that some of the water escapes its
usual boundaries.[13] While the size of a lake or other
body of water will vary with seasonal changes in
precipitation and snow melt, it is not a significant flood
unless the water covers land used by man like a village,
city or other inhabited area, roads, expanses of
farmland, etc.

Limnic eruptions
• A limnic eruption 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 landslides,volcanic activity, or explosions
can trigger such an eruption. To date, only two
limnic eruptions have been observed and
recorded:

Cyclonic storms
• Cyclone, tropical cyclone, hurricane,
and typhoon are different names for the same
phenomenon, which is a cyclonic storm system that
forms over the oceans. 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.

Extratropical cyclones
• Extratropical cyclones, sometimes called mid-latitude
cyclones, are a group of cyclones defined as synoptic scale
low pressure weather systems that occur in the middle
latitudes of the Earth (outside the tropics) not having tropical
characteristics, and are connected with fronts and horizontal
gradients in temperature and dew point otherwise known as
"baroclinic zones". As with tropical cyclones, they are known
by different names in different regions (nor'easter, Pacific
Northwest windstorms, European windstorm, East Asian-
northwest Pacific storms, sudestada, and Australian east coast
cyclones). The most intense extratropical cyclones cause
widespread disruption and damage to society, such as the
storm surge of the North Sea flood of 1953 which killed 2251
people in the Netherlands and eastern England, the Great
Storm of 1987 which devastated southern England and
France, and theColumbus Day Storm of 1962 which struck
the Pacific Northwest.

Droughts
• Drought is unusual dryness of soil, resulting in crop
failure and shortage of water for other uses, caused
by significantly lower rainfall than average over a
prolonged period. Hot dry winds, shortage of water,
high temperatures and consequent evaporation of
moisture from the ground can contribute to
conditions of drought.

Tornadoes
• A tornado is a violent, 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 acumulus cloud. It is also referred
to as a twister or a cyclone,[16] although the wordcyclone is used in
meteorology in a wider sense, to refer to any closed low
pressurecirculation. Tornadoes come in many shapes and sizes, but
are typically in the form of a visible condensation funnel, whose
narrow end touches the earth and is often encircled by a cloud
of debris and dust. Most tornadoes have wind speeds 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.

Health disasters
• An epidemic is an outbreak of a
contractible disease that spreads through a human
population. A pandemic is an epidemic whose
spread is global. There have been many epidemics
throughout history, such as the Black Death. In the
last hundred years, significant pandemics include:
• The 1918 Spanish flu pandemic, killing an estimated
50 million people worldwide

Space disasters
• Asteroids that impact the Earth have led to
several major extinction events, including one
that created the Chicxulub crater 64.9 million
years ago and associated with the demise of
the dinosaurs. Scientists estimate that the
likelihood of death for a living human from a
global impact event is comparable to death
from airliner crash. One of the notable impact
events in modern times was the Tunguska
event in June 1908.

• International law, for example Geneva
Conventions defines International Red Cross and Red Crescent
Movement theConvention on the Rights of Persons with
Disabilities, requires that "States shall take, in accordance
with their obligations under international law,
including international humanitarian law and international
human rights law, all necessary measures to ensure the
protection and safety of persons with disabilities in situations
of risk, including the occurrence of natural disaster."[23] And
further United Nations Office for the Coordination of
Humanitarian Affairs is formed by General
AssemblyResolution 44/182. People displaced due to natural
disasters are currently protected under international law
(Guiding Principles of International Displacement, Campala
Convention of 2009).[24]

Natural disasters

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