Opening - issue
Main section - Vulcano, earthquake, hurricane, tornado.
Ending - summary, konklusjon


Geography - Natural disasters

If you look up “natural disaster” in the dictionary will you find it explained as “an unexpected event which causes a lot of damage or suffering”. This may be a tremendous hurricane, a raging volcano, or any other natural disaster. In this article we will explain the four most known natural disasters; what causes them, how they develop and how they come to an end.

Cartoon_Tornado-earthquake-meteor.jpg
Volcano:

A volcano is an opening, or rupture, in a planet's surface or crust, which allows hot, molten rock, ash, and gases to escape from below the surface. Volcanic activity involving the extrusion of rock tends to form mountains or features like mountains over a period of time.
Volcanoes are generally found where tectonic plates are diverging or converging. A mid-oceanic ridge, for example the Mid-Atlantic Ridge, has examples of volcanoes caused by "divergent tectonic plates" pulling apart; the Pacific Ring of Fire has examples of volcanoes caused by "convergent tectonic plates" coming together. By contrast, volcanoes are usually not created where two tectonic plates slide past one another. Volcanoes can also form where there is stretching and thinning of the Earth's crust (called "non-hotspot intraplate volcanism"), such as in the African Rift Valley, the Wells Gray-Clearwater volcanic field and the Rio Grande Rift in North America and the European Rhine Graben with its Eifel volcanoes.
Volcanoes can be caused by "mantle plumes". These so-called "hotspots" , for example at Hawaii, can occur far from plate boundaries. Hotspot volcanoes are also found elsewhere in the solar system, especially on rocky planets and moons.

File:Rinjani 1994.jpg
File:Rinjani 1994.jpg


Earthquake:

An earthquake is a sudden release of high energy that creates seismic waves in the Earth’s crust. When an earthquake occurs it will be recorded with a seismometer, also called a seismograph how is telling who big an earthquake is and it can be used to warn people about it. An earthquake with magnitude 3 or lower will not be imperceptible. But if it is a magnitude on 7 it can causing serious damage over large areas.

The earthquake will manifest on the earth’s surface by shaking and some places displacing the ground. Sometimes a big earthquake can create a tsunami. the tsunami can cause a lot a death when it reaches the coast.

external image 070531_Kobe_earthquake.jpg


Tornado:

A tornado is a violent, rotating column of air which is in contact with both the surface of the earth and a cumulonimbus cloud or, in rare cases, the base of a cumulus cloud. Tornadoes come in many sizes but are typically in the form of a visible column, Most tornadoes have wind speeds between 40 mph and 110 mph
A waterspout is defined simply as a tornado over water. That supplies the tornado with warm air and water.
A multiple vortex tornado is a type of tornado in which two or more columns of spinning air rotate around a common center. Multivortex structure can occur in almost any circulation, but is very often observed in intense tornadoes. These vortices often create small areas of heavier damage along the main tornado path.
We can find tornadoes on every continent, not as strong as we mostly can find in the United States. The only area we can’t find tornadoes is on Antarctica

File:Trombe.jpg
File:Trombe.jpg


Tropical Cyclone:

A tropical cyclone is a storm with strong winds and flooding rain. The storm have a very large low pressure centre how is producing the strong winds, the rain and the thunderstorms. The tropical storm are getting his power form the heat how is released when most of the air rises from the ground and up. The tropical cyclones can offend be found near equator, and 25 degrees away from equator. It will not be found outside 25 degrees because it will not get strong enough on the basis of it is to cool in the water so fare away from equator. The tropical cyclones need warm water to get stronger. Tropical cyclones do not only make strong wind, thunderstorms and producing rain. They also produce high waves and damaging storms how can end in a catastrophic damage on villages and cities. Tropical cyclones gets there power from warm water and if they move over land, they loses there power and disappear. So people how lives inland will be safe from the damages the tropical cyclones make near the coastal. But the inland are not completely safe from the damages the storm has done with the coastal. The weather can become heavy rain how can produce flooding in the inland. But the strong winds that the cyclones produce are the inland people safe from.

File:Cyclone Catarina from the ISS on March 26 2004.JPG
File:Cyclone Catarina from the ISS on March 26 2004.JPG




In this paper we have explained how four different natural disasters arise and develop. They manifest themselves in different ways, but they all can cause a tremendous damage. Especially for poor people living in unsecure houses not made for these events. Humans can never get rid of these forces, but we can learn to live with them.

Almost every week we do here, in the news, about a natural disaster. It can be an avalanche in one of the narrow fjords of Norway or a devastating hurricane in the Caribbean, but it will always affect us and the way we live. We find the natural disasters very fascinating and the reason why we chose this subject is to learn more about and understand some of these strong phenomena of the nature.

By: Runar, Egil og Thord Sources:

Natural disaster. (23.02.09) URL: http://en.wikipedia.org/wiki/Natural_disaster [read: 24.02.09]
Volcano. (13.02.09) URL: http://en.wikipedia.org/wiki/Volcano [read: 24.02.09]
Earthquake. (06.02.09) URL: http://en.wikipedia.org/wiki/Earthquake [read: 24.02.09]
Tornado. (23.02.09) URL: http://en.wikipedia.org/wiki/Tornado [read: 24.02.09]
Tropical cyclone. (24.02.09) URL: http://en.wikipedia.org/wiki/Hurricane [read: 24.02.09]