Earthquakes
- Earthquakes are caused by the motion of tectonic plates—individual sections that make up the Earth's surface, like panels on a football.
- An earthquake is the shaking of the ground when there is a sudden breaking and shifting of these large plates.
- Earthquakes are amongst the most powerful natural disasters and can cause further disasters such as tsunamis and landslides.
- Earthquakes are measured by a seismometer which records the size of the seismic waves.
Example:
Newcastle, 28 December1989
This was the first earthquake ever to hit Australia. Although it didn’t rate too high on the Richter scale and only lasted five seconds, it killed 12 people and cost over $120 million worth of damage. This was largely due to the city not been prepared, in terms of its infrastructure, for such an event.
Volcanoes
- A volcano is a mountain where magma erupts though surface of the planet. The ‘crashing’ of tectonic plates at the plate boundaries causes this eruption.
- It is estimated that one in ten of the world's population live in the ‘danger range’ of a volcano.
- There are 1511 ‘active’ volcanoes across the globe and many more dormant ones that could recharge at any moment.
- More than half the world’s volcanoes are found on the edge of the Pacific Ocean.
Example: Japan 2005
The volcano Suwanose-jima is one of the most active volcanoes in the world. It is located on one of the northern islands of Japan. Currently there are only around 50 people living near the volcano. Its longest eruption, in 1913, lasted one year and lava flows reached the opposite side of the island.
Tornadoes
- Tornadoes occur when warm and cool airstreams collide and storm clouds form in a rotating area of low pressure. The air within the low-pressure front then rises creating a strong vacuum-like effect.
- The UK is the most tornado-prone country in the world
- Speeds can reach up to 300mph. Tornadoes are rarely larger than 250m across.
Example: Birmingham 28th of July 2005
Winds in Birmingham, England reached 130 mph and resulted in 20 people injured and a further 3 seriously injured. The tornado also displaced hundreds of residents for up to one week. The estimated damage is unknown however it is believed to be the worst tornado in England in over 25 years.
Floods
- Floods are the submergence of an area by water. They can be caused by heavy rainfall, hurricanes, melting snow or tsunamis.
- A flash flood is the rapid flooding of a low-lying region caused by heavy rainfall.
Example: Lismore 30 June 2005
The Lismore flood caused 6000 people to evacuate their homes, but luckily as the city was prepared no one was hurt. Lismore is in a flood-prone area and had previously been evacuated due to flooding.
Hurricanes/Cyclones
- A hurricane is fierce storm with an intense centre of low pressure. They usually occur in the tropics.
- The exact reasons why hurricanes occur is still under extensive investigation but they are thought to be caused by air above tropical water rising as it is heated by the sea. As the air rises it rotates or spins forming the eye of a hurricane.
- A hurricane moves rather slowly, at speeds between 20–25mph, but brings torrential rain, thunderstorms and very strong winds. Sometimes flooding results in low-lying areas.
Example: Hurricane Katrina 29 August2005
The hurricane hit New Orleans and Buras, Louisiana and is the third most intense hurricane on record in the US. The hurricane is estimated to have caused over 11,000 deaths and displaced over a million US citizens. The Hurricane caused up to $120 billion of damage due especially to the flooding of New Orleans.
Tsunamis
- A tsunami is a chain of fast moving waves caused by a sudden trauma in the ocean. Earthquakes, volcanic eruptions or even the impact of meteorites can cause them.
- Tsunamis are often confused with tidal waves, but unlike tidal waves, they are not caused by tidal changes.
- Tsunamis can strike with virtually no warning and most commonly occur around the edge of the Pacific Ocean.
Example: Indian-Ocean tsunami 26December 2004
This tsunami was caused by an underwater earthquake of up to 9.15 in magnitude, making it the second largest earthquake ever reported. The tsunami affected Sri Lanka, Indonesia, the Maldives, Somalia, Myanmar, Malaysia, South India and Thailand, with the furthest death recorded in South Africa. The death toll is believed to be up to 250,000; however the impacted areas have also been affected by aftermaths such as famine and the spread of disease.
Droughts
- A drought is caused by insufficient rainfall which causes the land to become starved of nourishment and unable to support growth.
- Droughts have been known to cause famine, bushfires, migration, social unrest and disease.
- Droughts are the most likely natural disaster to affect Australia, as it is the driest inhabited continent.
Example: Australia 2005
The current drought is mainly evident in rural areas where farmers have been struggling and animals and crop have been dying. This year (2005) was the driest ever recorded in Australia and has led to water restrictions. In parts of NSW, level 3 restrictions have been implemented. This means hand held hoses can only be used to water lawns and gardens at specific times, sprinklers are banned, permits are required to fill pools larger than 10,000 litres and hard surfaces can't be hosed at any time. If the restrictions are broken, fines can be issued, a necessary measure taken to get through the disaster.
How do I know this?
BBC,
http://www.bbc.co.uk
Dictionary.com,
http://dictionary.reference.com/
Smithsonian Institution, Global Volcanism Program,
http://www.volcano.si.edu/index.cfm
Sydney Water,
Saving Water,
http://www.sydneywater.com.au/SavingWater/WaterRes...
ThinkQuest,
Natural Disasters: Destructive Forces of Nature http://library.thinkquest.org/16132/frames.html
Wikipedia,
http://www.wikipedia.org/
WorldBook Online Reference Center,
http://www.aolsvc.worldbook.aol.com/
