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Land Slide Facts!
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This wikispace is a kit full of information about what a LANDSLIDE is, how it happens, management strategies and more. Since 1842, there have been 100 recorded landslide events which have resulted in the death of 105 people and injury to 129 (National Landslide Database, 2007). Although many of these landslides have resulted from natural phenomenon, almost half of those causing death and injury can be attributed to human activity. This kit was created by the Australian Natural Hazards Task Force to inform you about landslides.

What is a landslide?
A landslide is when a wide range of ground movement is happening, such as rock falls. This can occur offshore, coastal and onshore environments. Gravity is the primary driving force for a landslide to occur, there are also other factors that contribute to affecting the slope stability.

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What causes landslides?
The main factors are the climate, the angle of the slope, water content, weathering, overloading and vegetation.

Natural causes of landslides: Ground water pressure to destabilize the slope, loss of soil or vegetation, erosion of the toe of a slope by rivers or ocean waves, weakening of a slope through snowmelt, glaciers melting, or heavy rains, earthquakes adding loads to barely-stable slopes, volcanic eruptions.

Human causes: Deforestation, cultivation and constructions, which destabilize the slopes. Vibrations. Blasting. Earthwork which alters the shape of a slope. The removal of deep-rooted vegetation that binds colluviums to bedrock. Construction and agricultural activities.

The types of landslide movements:
Flow: Flows have a high water content making the slope loose stability. This is the most destructive and turbulent form of landslide since it happens so quickly.
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Topple: Forward rotation of rocks about a pivot point, topples have a rapid movement. Material descends by abrupt falling, sliding, bouncing and rolling.external image ls-fig09.gif

Fall: Rapid movement with materials falling at freefall periods. This type of landslide movement is usually triggered by earthquakes or erosion processes.external image ls-fig10.gif

Slide/ Slump: This is one of the most common types of landslide movement. Slides/ Slumps are most common when the toe of the slope is undercut. external image rockslide_schematic.gif

Slide
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Slump

Spread: This is characterized by the movement of lateral displacement of large volumes of distributed material over very gentle or flat land. This type of landslide is caused by liquefaction (when saturated loose sediment such as sand, are transformed into a liquid state). This process is triggered by rapid ground motion most commonly during earthquakes
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These landslides​ have occurred mostly around the east coast of Australia, as you can see in the diagram below:

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The green dots are were the landslides have happened.

Thredbo Landslide:
The Thredbo landslide was a catastrophic landslide that occurred at the village and ski resort of Thredbo, New South Wales, Australia. Eighteen people died when the two lodges collapsed at Thredbo Alpine Village at 11:35 pm on Wednesday of July 30th 1997. About 3,500 tonnes of debris came down the slope.

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Social Effects: The landslide killed 18 people. There was only one survivor, called Stuart Diver who was a ski instructor at the ski resort. After the rescue team had given up searching for survivors, the rescue workers saw some movements under a concrete slab and five minutes later the rescue team started working to save Stuart. Stuart was beneath two concrete slabs, five hours later, rescuers had removed enough of the rubble for them to be able to touch Diver. Paul Featherstone was the paramedic who kept talking to Diver for 11 hours until he was freed.

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Environmental Effects: The environment suffered quite heavily in the initial stage of the landslide with the short-term impacts of erosion, loss of top soil and the loss of the remaining vegetation and trees. This meant loss of some native animal habitats.
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Economic Effects: Reconstruction of the Alpine Way after the Thredbo landslide cost $24 million. Then there were ongoing costs: for example, following the disaster, insurance premiums for Alpine lodges increased significantly, while the NSW State Government has, to date, spent $40 million in out-of-court settlements with 91 businesses and individuals relating to the disaster. After the report of the disaster, people lost a lot of tourism leading to less money at that time.
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Management Strategies:
Factors that prove potential landslide sites:

  • Saturated ground or seeps in areas which are not typically wet
  • New cracks and scraps or unusual bulges in the ground
  • Movement of structures
  • Sticking doors and windows
  • Tilting or cracking of concrete floors or foundations
  • Broken water lines and other underground utilities
  • Leaning telephone poles, trees, fences...
  • Offset fence lines
  • Sunken road surfaces
  • A quick increase in creek water levels.

How can you help to de protected from this disaster:
You could research more on the natural disaster, such as know where most landslides happen in Australia. You could learn more about what climatic situations trigger a landslide. Ask a specialist from Geoscience Australia for ways to protect yourself or ask them if you live on a potential landslide area and if you do you should ask them if they can do anything to prevent or decrease the possibilities of this disaster from happening. You could search the web about management strategies:
http://www.ema.gov.au/www/emaweb/emaweb.nsf/Page/EMA_Library


Bibliography:
http://www.district.north-van.bc.ca/article.asp?c=1024
http://en.wikipedia.org/wiki/1997_Thredbo_landslide
http://www.ema.gov.au/www/ema/schools.nsf/Page/Get_The_FactsLandslides
http://www.smh.com.au/news/National/Thredbo-disaster-at-last-the-facts/2004/12/02/1101923273802.html
http://www.epicski.com/forum/thread/57470/in-memoriam-thredbo-landslide-30-july-1997

http://en.wikipedia.org/wiki/1997_Thredbo_landslide