NATURAL DISASTERS

English Integrated Project

What are natural disasters?• A natural disaster is a major adverse event

resulting from natural processes of the Earth ; examples include floods ,volcanic eruptions,earthquakes,tsunamis,and other geologic processes.

• A natural disaster can cause loss of life or property damage and typically leaves some economic damage in its wake, the severity of which depends on the affected population'sresilience, or ability to recover.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 asSan Francisco and Nepal, an earthquake can have disastrous consequences and leave lasting damage, requiring years to repair.

Floods •A flood is an overflow of water that "submerges" land.

The EU Floods Directive defines a flood as a temporary covering by water of land not normally covered by water.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.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.

Causes and Effects Natural disasters happen all over the

world, and they can be utterly devastating for people’s lives and the environments in which they live. Although natural disasters are caused by nature and there is nothing that we can do to prevent them happening, there are many different natural causes that lead to natural disasters, and being aware of these causes enables us to be better prepared when such disasters do arrive.One common natural disaster is flooding, which occurs when a river bursts its banks and the water spills out onto the floodplain. This is far more likely to happen when there is a great deal of heavy rain, so during very wet periods, flood warnings are often put in place.

Causes and Effects There are other risk factors for flooding

too: steep-sided channels cause fast surface run-off, while a lack of vegetation or woodland to both break the flow of water and drink the water means that there is little to slow the floodwater down. Drainage basins of impermeable rock also cause the water to run faster over the surface. Earthquakes are another common natural disaster that can cause many fatalities. The movements of the plates in the earth’s crust cause them. These plates do not always move smoothly and can get stuck, causing a build-up of pressure. It is when this pressure is released that an earthquake occurs. In turn, an earthquake under the water can also cause a tsunami, as the quake causes great waves by pushing large volumes of water to the surface.

Causes and Effects Tsunamis can also be caused by

underwater volcanic eruptions. Volcanic eruptions are another natural disaster, and they are caused by magma escaping from inside the earth. An explosion takes place, releasing the magma from a confined space, which is why there are often also huge quantities of gas and dust released during a volcanic eruption. The magma travels up the inside of the volcano, and pours out over the surrounding area as lava. One of the most common natural disasters, but also one of the most commonly forgotten, is wildfires. These take place in many different countries all over the world, particularly during the summer months, and can be caused by a range of different things.

Causes and Effects

Examples

Epidemics• An epidemicis 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 theBlack Death. In the last hundred years, significant pandemics include:

• The 1918 Spanish flupandemic, killing an estimated 50 million people worldwide

• The 1957–58 Asian flupandemic, which killed an estimated 1 million people

• The 1968–69Hong Kong water flupandemic• The 2002-3SARSpandemic • The AIDS pandemic, beginning in 1959• The H1N1 Influenza(Swine Flu) Pandemic 2009–2010\• Other diseases that spread more slowly, but are still

considered to be global health emergencies by theWHO, include: XDR TB, a strain of tuberculosis that is extensively resistant to drug treatments. Malaria, which kills an estimated 1.6 million people each year. Ebola virus disease, which has claimed hundreds of victims in Africa in severaloutbreaks

Avalanches• During World War I, an estimated 40,000 to

80,000 soldiers died as a result of avalanches during the mountain campaign in the Alpsat the Austrian-Italian front. Many of the avalanches were caused by artillery fire.

Earthquakes•An earthquake is the result of a sudden

release of energy in theEarth'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.

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.

By Vimal Kumar