landslides




The Australian continent experiences a range of natural hazards, and each natural hazard has different risks to the community. A natural hazard is when the forces of nature combine to become destructive including cyclones and storms, floods, bushfires, droughts, earthquakes and landslides.When a natural hazard impacts on a community causing destruction of property and lives, the natural hazard becomes a natural disaster.

This information kit will inform you on the following things: Why the thredbo landslide is a natural disatser, what a landslide is, what causes a landslide, where landslides occur, different perspectives on landslides and management strategies for future landslides. In particular this kit will be focusing on the Thredbo landslide of 1997.








external image Landslides_explained_large.jpg

What is a landslide?

A landslide is the movement of rock, debris or earth down a slope, under the force of gravity. They occur when tension cracks in the ground appear and begin to cause a scarp. As this tension increases and significant changes in moisture occur, such as things like heavy rainfall and melting of snow, the land will begin to move more and more, which will eventually cause a landslide.












What causes a landslide?

The overall factors that contribute to whether a ladslide will occur, include:the slope angle of the hill, the weathering and climate of the area,water content, vegetation, overloading, geology, and slope stability.
Landslide types (Images courtesy of British Geological Survey)
Landslide types (Images courtesy of British Geological Survey)

Basic types of landslide movement:
Fall- commonly triggered by eearthqaukes or erosion and is generally characterised by rapid movement.
Topple- generally characterised by the tilting of a rock. The material of the landslide generally descents by falling, sliding, bouncing or rolling.
flow- flows have high water content causing the slope material to be rapid and it turns it into slurry.
Slide- has a moderate rate of movemrnt and the material is ooften in tact or broken into pieces.
Spread- triggered by a rapid ground motion most commonly during earthqakes
.



Landslides occur when the stability of the slope changes from stable to unstable. A change in the stability of a slope can be influenced by many factors, some natural factors may include:
-earthquakes
-volcanic eruptions
-erosion
-weakening of a slope through melting of ice or heavy rainfall
-loss of vegetative structure and soil structure though wildfires

human factors include:
-vibrations of machinery or traffic
-deforestation
-construction
-blasting












Where do landslides occur?
Landslide prone areas are most commonly charactised by cliffs, steep slopes, or gental slopes of unstable geology and areas which have had long periods of heavy rainfall.
Landslides in Australia (Copyright Geoscience Australia)
Landslides in Australia (Copyright Geoscience Australia)


This image above shows the parts of australia which are affected by landslides. The image below shows where most people in australia live. From these images you can see that where the landslides are occuring, and that they are occuring mostly around the coastal areas where there are high populations of people living.

external image 3gcoverage.jpg










The thredbo landslide of 1997




On July 30, 1997 a landslide rolled over the ski resorts of thredbo, australia .It was a catastrophic event which buried 18 people alive, along with cars and 2 ski resorts. It brought one thousand tones of rock, trees and debris down the slope of the mountain cutting a four hundred meter wide swath.


external image Thredbo_landslide_As_night_falls_rescue_workers_continue_to_shift_throught_the_rubble_24_hours_around_the_clock_20_people_are_missing.jpgexternal image r164129_606059.jpgexternal image Thredbo_landslide_As_night_falls_rescue_workers_continue_to_shift_throught_the_rubble_24_hours_around_the_clock_20_people_are_missing.jpg














What caused the thredbo landslide?
The landslide was caused by a water leak from a ruptured pipe that ran alongside the alphine road situated above the two lodges Bimbadeen and Carinya. The leaking water pipe caused the ground to become lubricant causing the road to collapse on the two lodges.

external image BigObjFileManager?bigobjid=GA9643

The image above show the road of which was built over the pipe that leaked and was one of the main contributors towards the landslide. It also shows how much damage was caused by the landslide.









economic impacts:
Reconstruction of the Alpine Way after the Thredbo landslide cost $24 million. There were also 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. Lots of money had to be spent to repair and rebuild the community. One hundred professional services were called to the scene along with many volunteers. Also many people were afraid to return to the area which resulted in the loss of tourists money$$.

hjdhasdlas.png
hjdhasdlas.png












Social impacts:
Some social impacts associated with the thredbo landslide would be all the different ages of men and women, boys and girls that were injured in the landslide, ansd also the 18 people that died due to this unfortunate event. Also the stress that was put onto the community to try and help and organise search and rescue as soon as possible to have a chance of rescuing some of the servivors. Tourism would have also had been a social impact because this would have affected the communities buisnesses as well, and they would have lost lots of money from tourists being to scared to come back, incase this event re-occurs.

oimg.png
CHART 1










Enviromental impacts:.
Long term impacts included the community becoming more aware of the importance of using vegetation in order to stabilize cliffs and hill sides and also forced the government re-consider the construction of safer roads to prevent further reoccurrence of such a disaster. It should be remembered that landfill was used to help build up the Alpine Way above the ski resorts which collapsed, and the incident showed the unsuitability of such methods for building roads in snowy areas.

environment.png
chart 7






envi.png
chart 8









Management strategies for futuree landslides:
Since the thredbo disaster the NSW fire brigade has further expanded its urban search and rescue capabiility including the development of strategic partnerrship with other NSW and intersstate emergancy services.
The government has taken certain measures to reduce the risks of landslides happening and to reduce the risk of endangerment to property and lives. Some of these measures would be to upgrade substandard slopes, to maintain all government slopes, ensure the safety of new slopes and to clear squatters from areas with landslide hazards. One of their main tarkets to reach is to promote public awareness and obtain public co-operation to protect their own safety through education. They are also providing expert advice to protect public safety through the landslide warning systemand emergancy control center.
The local governments have also began taking steps in ensuring that the land is stable before construction takes place.




external image Landslides_Thredbo_thumb.jpgexternal image Diver-5368765.jpgexternal image auStretch.jpg












The images above show how well organised the search and rescue teams were and how well the community worked together to save as many lives as possible.












Bibliography:

"landslide." landslide. Web. 1 July 2010. <http://en.wikipedia.org/wiki/Landslide>.
"what is a landslide."
australian government;geoscience australia. Web. 1 July 2010. <http://www.ga.gov.au/hazards/landslide/>.
"australian landslide."
australian landslide. Web. 1 July 2010. <http://www.9-1-1magazine.com/magazine/1998/0398/features/52zakis.html>.
"landslide."
1997 thredbo landslide. Web. 1 July 2010. http://en.wikipedia.org/wiki/1997_Thredbo_landslide.
"landslide."
1997 thredbo landslide. Web. 1 July 2010. <http://en.wikipedia.org/wiki/1997_Thredbo_landslide>.
"natural hazards."
landslides. Web. 1 July 2010. <http://geog.tamu.edu/sarah/australia/naturalhazardsAU.pdf>.
"landslides."
landslides. Web. 1 July 2010. <http://www.google.com/imgres?imgurl=http:www.topnews.in/files/landslides546.jpg&imgrefurl=http://www.topnews.in/air-tides-responsible-causing-landslides-2231418&usg=__MeeQOa1qwUY9Li9WVD1BKnuUsjM=&h=825&w=1032&sz=135&hl=en&start=2&sig2=AntyHv_hGFVKv1sqbHzjCA&tbnid=EVxWZPkXx9N4_M:&tbnh=120&tbnw=150&ei=JRlITJP0No-8cb_QwLMM&prev=/images%3Fq%3Dlandslides%26hl%3Den%26biw%3D1362%26bih%3D527%26gbv%3D2%26tbs%3Disch:1&itbs=1>.