An adverse event will not rise to the level of a disaster if it occurs in an area without vulnerable population.[3][4] In a vulnerable area, however, such as San Francisco and Nepal, an earthquake can have disastrous consequences and leave lasting damage, requiring years to repair.
In 2012, there were 905 natural disasters worldwide, 93% of which were weather-related disasters. Overall costs were US$170 billion and insured losses $70 billion. 2012 was a moderate year. 45% were meteorological (storms), 36% were hydrological (floods), 12% were climatological (heat waves, cold waves, droughts, wildfires) and 7% were geophysical events (earthquakes and volcanic eruptions). Between 1980 and 2011 geophysical events accounted for 14% of all natural catastrophes.[5]
The differents kind of natural disasters.
Earthquakes
See also: Lists of 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.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, tsunamis
(seismic sea waves) and volcanoes, that are actually the human
disaster. Many of these could possibly be avoided by better
construction, safety systems, early warning and planning.Volcanic eruptions
Main articles: List of largest volcanic eruptions and Types of 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. 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.
A specific type of volcano is the supervolcano. According to the Toba catastrophe theory, 75,000 to 80,000 years ago a supervolcanic event at Lake Toba reduced the human population to 10,000 or even 1,000 breeding pairs, creating a bottleneck in human evolution.[8] It also killed three-quarters of all plant life in the northern hemisphere. 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.
See also: List of floods
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 a cumulus cloud. It is also referred to as a twister or a cyclone,[13] 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 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. 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).
Avalanches
An avalanche is a geophysical hazard caused by a large amount of snow
sliding down a mountainside. It is a common sight in some mountains in
winter. When an avalanche moves towards ground level, it gains mass by
amassing snow from the snowpack and is usually at its highest speed when
it gets nearer to the bottom of the slope. An avalanche occurs when the
snow packed down on the surface fails to carry its weight. Rapid wind
speed, major temperature changes, and manmade influences are other
common factors causing avalanches. Extratropical cyclones
Main article: Extratropical cyclone
Hurricanes
Cyclones, tropical storms, typhoons, and hurricanes describe the same
disaster type. Basically, these types of natural disasters refer to a
closed circulation system in the atmosphere that consists of strong
winds and low pressure. The winds rotate clockwise in the southern
hemisphere and counter clockwise in the northern hemisphere. A tropical
cyclone is usually characterized by a low-pressure center with strong
winds and spiral rain bands. Drought
A drought is an extended period of months or years when a region suffers a severe deficiency in its water supply. Generally, this occurs when a region receives consistently below average rainfall. 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 the local economy.
Why do natural disasters happened?
Soil erosion is caused by the wind and rain which washes away soil and rocks. This can be a
contributing factor for flooding, mudslides and landslides. The change in ocean currents can change the temperature of the seas, which can increase the intensity or frequency of storms as well as kill sea life, which can lead to food shortages.
Air pressure and the interaction between high and low pressure, which can also be caused by changes in sea temperature are the cause of many natural disasters. Tornadoes, thunderstorms and hurricanes are all caused by this interaction. The rain and wind alongside these weather systems can cause serious damage to property as well as cause flooding. Along with soil erosion during a storm, rivers can burst their banks, adding to the floods.
Seismic activity is responsible for earthquakes, typhoons and volcano eruptions. As tectonic plates around the Earth shift, rubbing against each other, energy can build up. Once this energy is released, it can cause earthquakes which can cause typhoons or tsunamis. Volcanoes erupt when this pressure builds up and causes molten rock from the lower parts of the Earth's crust to be expelled from the crater.
What are the effect of natural disasters?
They
are most of the previous answerer's posts but here is what mankind can
do to mitigate many of them,learn how to build runoff aqua-ducts to feed
drought stricken areas that do not get rainfall,build better
infrastructure that can withstand tsunamis as has been done in New Orleans that President Obama has denied operating funds to and learn how
these natural disaster's happen such as tornadoes and some day we may
learn how to defuse them.The problem is the funding.There is growing
concern that we must stop bailing out the wall street bankers that
continue the same speculative gambling with the funds they've been
looting from the tax payers that our politicians have been passing off
onto us as national debt and reverse these funds and invest them back
into these needed programs instead to not only create needed jobs on a
massive scale but to begin rebuilding the farms,factories and various
industries that have also been looted and shut down due to the wall
street speculators doing what is known as "buy low,sell dear".That is
where they dismantle companies and sell off all of their machinery and
tools of the trade they bought out and make the company no longer
exist.They've destroyed small business and have been doing it for so
long that there's nothing left loot.They scrap whole corporations and
have been shutting down everyone's jobs.When there's no steel plants
left,no farms left,etc...then people cant's continue creating new
products and new technologies to fix these problems.We need to build
NAWAPA,(North American Water And Power Alliance),take the Google tour
and learn how we have the technology to Terraform deserts,how the
effects of re-hydrating areas of the earth actually change weather
patterns and creates plush,forested lands,redistributes mass water and
creates spinoff jobs in many fields of employment.Farming is a big one
which would establish an increasing supply of food.Many types of jobs
require fresh water,NAWAPA diverts the 90% fresh water glacier and snow
in Alaska that just flows back into the ocean,thus being lost to use and
wasted.There are mining jobs galore that would open up as a result of
NAWAPA. Anyway,that's just one example but there are videos of this program here:
How to prevent the natural disasters
When aid organizations intervene to address malnutrition and prevent famine, they have tools at their disposal that were unimaginable a decade ago. For instance, Plumpy’Nut, a peanut paste that contains vegetable oil, milk powder, vitamins, and minerals and costs less than fortified milk formulas, revolutionized the aid scene during the recent food crisis in Niger. Referred to as a “miracle product,” Plumpy’Nut has streamlined the aid operations of several organizations.
“In 2002 it took 2,000 staff to treat 10,000 children during a famine inAngola,” Stephane Doyon, a nutrition team leader at Medecins Sans Frontieres Doctors without Borders told the BBC in April 2010. “In Niger we needed just 150 staff for the same number of patients. Thanks to Plumpy’Nut, mass treatment is suddenly possible.”
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