Gada's Natural Disaster Page

A disaster is an accidental event that causes many deaths and injuries. Most disasters also result in major property damage. Common natural causes of disasters include earthquakes, floods, hurricanes, typhoons, and tornados. Tsunami, volcanic eruptions, bushfires, landslides and avalanches can also cause natural disasters. Natural disasters are produced by the forces of nature. Recently there was a flood in Queensland which destroyed many houses. There was a bushfire near Crookwell and in 1998 there was a really bad flood in Wollongong. In 1974 Cyclone Tracey caused a lot of damage in Darwin.
Tornados
Tornados are usually accompanied by a funnel-shaped cloud extending down from a cumulonimbus cloud. Often called twisters, a tornado can be a few metres to about one kilometre wide where it touches the ground, with an average width of a few hundred metres. It can move over land for distances ranging from short hops to many kilometres, causing spectacular damage where ever it descends. The funnel is made visible by the dust sucked up and by condensation of water droplets in the centre of the funnel. The same condensation process makes visible the weaker sea-going tornados, called water spouts, that occur mostly in tropical waters. Most tornados spin counter clockwise in the northern Hemisphere and clockwisse in the Southern Hemisphere. But occassionally, tornados reverse this behaviour. Tornados are most common and strongest in temperate zones.
Hurricanes
Hurricane is a name applied to tropical cyclones that originate over oceans in certain areas near the Equator. Hurricanes are also known as typhoons. Hurricanes occur in the north Atlantic Ocean but not in the south Atlantic Ocean. They also occur in both the north and south Pacific Ocean but are usually called typhoons or tropical cyclones here.
Avalanches
An avalanche is a sudden flow of a large mass of snow or ice down a slope or cliff, sometimes at speeds more than 160 km/h. Such flows can destroy life and property. Avalanches are most common on steep slopes. Avalnaches are set off by a combination of things, including temperature and sudden vibrations, including loud noises. Snow patrols in mountain areas reduce the hazard by detonating explosives that cause smaller, less destructive snow flows. A landslide is a similar big movement of rock and soil.
Tsunami
Tsunami, the Japanese word meaning "harbour wave", is also the word used as the scientific term for seismic sea waves generated by an undersea earthquake or possibly an undersea landslide or volcanic eruption. When the ocean floor is tilted during an earthquake, a set of waves is created, like the waves begun when an object is dropped into water. Most tsunami begin along the "ring of fire", a volcanic and earthquake zone 32500 kilometres long, that encircles the Pacific Ocean. Since 1819 about 40 tsunamis have struck the Hawaiian Islands. A tsunami can have waves of 100 to 200 km long, and may travel hundreds of kilometres across the deep ocean, reaching speeds of about 725 to 800 km/h. Upon entering shallow coastal waters, the wave, which may have been only half a metre high, becomes very much larger. Tsunamis have tremendous energy because of the great volume of water in them. They are able to completely destroy coastal towns and villages as happened in Aitape in New Guinea in 1998.

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