2. Natural Disasters A natural disaster is the effect of a
natural hazard (e.g., flood, tornado, hurricane, volcanic eruption,
earthquake, or landslide) Disasters Disasters are hazards that
cause destruction or environmental changes. The types are Natural
disasters
3. List of top 10 natural disasters 1. Cyclone 2. Earthquake 3.
Tornado 4. Volcanic Eruption 5. Tsunami 6. Flood 7. Landslide 8.
Drought 9. Waterspout 10. Wildfire
4. Cyclones A cyclone is an area of closed, circular fluid
motion. It has low pressure on the inside and high pressure on the
outside. The center of the storm is called the eye and it has the
calmest water and the lowest pressure Cyclones turn
counter-clockwise in the northern hemisphere and clockwise in the
southern hemisphere. This is because it follows the rotational
movemeent of the earth. The biggest cyclone recorded is the Bhola
cyclone. It hit the coast of today's Bangladesh in 1970 with a
death toll of around 500,000.
5. Earthquakes . An earthquake (also known as a quake, tremor
or temblor) is the perceptible shaking of the surface of the Earth,
which can be violent enough to destroy major buildings and kill
thousands of people. The severity of the shaking can range from
barely felt to violent enough to toss people around. Earthquakes
have destroyed whole cities. They result from the sudden release of
energy in the Earth's crust that creates seismic waves. The
seismicity, seismism or seismic activity of an area refers to the
frequency, type and size of earthquakes experienced over a period
of time. The power of an earthquake is measured by Richter
scale
6. Tornados (Twisters) A tornado is a violently 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.
They are often referred to as twisters or cyclones, although the
word cyclone is used in meteorology, in a wider sense, to name any
closed low pressure circulation. Tornadoes come in many shapes and
sizes, but they 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 (180 km/h), are about 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 miles per hour (480 km/h), stretch more than two
miles (3 km) across, and stay on the ground for dozens of miles
(more than 100 km).
7. Volcanic Eruption Several types of volcanic eruptionswherein
lava , tephra (ash , lapilli , volcanic bombs and blocks), and
assorted gases are expelled from a volcanic vent or fissurehave
been distinguished by volcanologists. Some volcanoes may exhibit
only one characteristic type of eruption during a period of
activity, while others may display an entire sequence of types all
in one eruptive series. There are three different meta types of
eruptions. The most well- observed are magmatic eruptions, which
involve the decompression of gas within magma that propels it
forward. Preheat o magmatic eruptions are another type of volcanic
eruption, driven by the compression of gas within magma, the direct
opposite of the process powering magmatic activity. The last
eruptive metatype is the prehatic eruption, which is driven by the
superheating of steam via contact with magma; these eruptive types
often exhibit no magmatic release, instead causing the granulation
of existing rock.
8. Tsunamis A tsunami called the "harbour wave" also known as a
seismic sea wave or as a 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. Earthquakes , volcanic
eruptions and other underderwater explosions , landslides,
meteorite impacts and other disturbances above or below water all
have the potential to generate a tsunami. Tsunami waves do not
resemble normal sea waves, because their wavelength is far longer.
Rather than appearing as a breaking wave, a tsunami may instead
initially resemble a rapidly rising tide, and for this reason they
are often referred to as tidal waves. Tsunamis generally consist of
a series of waves with periods ranging from minutes to hours,
arriving in a so-called "wave train". Wave heights of tens of metrs
can be generated by large events. Although the impact of tsunamis
is limited to coastal areas, their destructive power can be
enormous and they can affect entire ocean basins the 2004 Indian
Ocean tsunami was among the deadliest natural disasters in human
history with at least 230,000 people killed or missing in 14
countries bordering the Indian Ocean.
9. Landslides A landslide or a landslip is a movement in the
ground and a shallow flow of debris. The largest landslide in
history happened because of Mount St. Helens. 3km of rock moved
downhill. A landslide, also known as a landslip, is a geological
phenomenon that includes a wide range of ground movements .
Rockfalls , deep failure of slopes and shallow debris flows were
common. Landslides 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.
10. Floods . Flooding may occur as an overflow of water from
water bodies, such as a river or lake, in which the water overtops
or breaks levees, resulting in some of that water escaping its
usual boundaries, or it may occur due to an accumulation of
rainwater on saturated ground in an areal flood. Floods can also
occur in rivers when the flow rate exceeds the capacity of the
river channel, particularly at bends or meanders in the waterway.
Floods often cause damage to homes and businesses if they are in
the natural flood plains of rivers. One of the biggest floods in
the world is probably the Yellow river in China 1887 which killed
between around 900,000
11. Droughts Drought is an extended time when a region receives
a deficiency in its water supply , whether atmospheric, surface or
ground 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. Annual dry seasons in the tropics significantly
increase the chances of a drought developing and subsequent bush
fires. Periods of heat can significantly worsen drought conditions
by hastening evaporation of water vapor. Many plant species, such
as those in the family . Cacti, have adaptations like reduced leaf
area and waxy cuticles to enhance their ability to tolerate
drought. Some others survive dry periods as buried seeds. Lasting
three years from 1958 to 1961, the Great Chinese Famine is the
worst on record, 15 to 43 million were killed as a result .
12. Water spouts A waterspout is an intense columnar vortex
(usually appearing as a funnel-shaped cloud) that occurs over a
body of water. They are connected to a towering cumuliform cloud or
a cumulonimbus cloud. In the common form, it is a non-super cell
tornado over water. Most waterspouts do not suck up water; they are
small and weak rotating columns of air over water. While
waterspouts form mostly in the tropics and subtropical areas, other
areas also report waterspouts, including Europe, New Zealand, the
Great Lakes and Antarctica. Although rare, waterspouts have been
observed in connection with lake-effect snow precipitation bands.
Waterspouts have a five-part life cycle: formation of a dark spot
on the water surface, spiral pattern on the water surface,
formation of a spray ring, development of the visible condensation
funnel, and ultimately decay.
13. Wildfire A wildfire is an uncontrolled fire in an area of
combustible vegetation that occurs in the countryside area. / 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. Other names for a wildfire are brush
fire, bushfire, forest fire, desert fire, grass fire, hill fire,
peat fire, vegetation fire, and veldfire.