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Natural disaster report scl-lanslides

Lillie McDonagh

on 1 November 2012

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Transcript of Landslides

Landslides By Lillie McDonagh 6G What Is A Landslide? A landslide is movement of rock or debris down a slope. Landslides occur when rocks and sediment loosen and quickly roll down some sort of embankment. If the plants or tree roots that hold the soil of the slope together are damaged or burnt in a wild fire, gravity will then take over, forcing the soil and rocks down the slope. What Causes A Landslide? A landslide can occur when an area is worn down by the weather. Earthquakes can also make rocks and soil unstable, causing them to break apart, forming a landslide. Another cause of landslides is chemical weathering, this is when water dissolves rocks and changes their chemistry. Landslides can also be an after effect of another natural disaster like volcanic eruptions, these landslides are usually extremely hot, high speed and dangerous. Gravity is the force that pulls all matter together and it plays a major role in the occurrence of landslides. Without gravity the soil and rocks would not move down the slope. Gravity's Effect
On Landslides 1.Fall – rapid rate of movement, caused by earthquakes, erosion processes
2.Topple – tilting of rock without collapse, material descends by abrupt falling, rolling, sliding
3.Flow – most destructive and turbulent, channeled by landscape, move rapidly, the high water content causes the material of the slope to lose cohesion
4.Slide – common, translational and rotational slides, material moves either largely intact or in broken pieces, translational slides have a two dimensional surface of rupture, moderate rate of moving
5.Spread – caused by liquefaction, displacement of large volumes of distributed material over a very gentle or flat terrain Basic Types Of
Landslide Movement The Effects Of A Landslide Landslides can cause problems like millions of dollars damage to buildings, roads, pipelines, railways, communication networks, agricultural land, facilities and environmental degradation. Large numbers of people can be killed if a landslide occurs in an area of dense human habitation. Landslide Warning System 'Sound of the underground' is a new acoustic early warning system for landslide prediction. This consists of a network of sensors buried across the hillside or embankment that could possibly collapse. The sensors measure the acoustic behavior of the soil, record any movement in the soil and transmits a signal to a central computer to be analysed. Increased acoustic movements mean that a slope is close to collapsing and when the sound recorded reaches a certain noise rate, the system will send a warning via text message to the authorities that are responsible for the safety and protection of that area. If warned early enough it enables those authorities to evacuate the area, close any transport routes that will cross the slope or carry out works to stabilise the soil to prevent it from falling. This was developed by researchers at Lough borough university collaborated with the British Geological Survey through two projects that were funded by the Engineering and Physical Sciences Research council (EPSRC). A way of warning people that a certain area is a landslide hazard area is by signs. According to the United States Geological Survey, the biggest landslide ever recorded occurred on May 18th, 1980, triggered by the eruption of Mount St Helen's. Mount St Helen's is a volcano located in the Cascade Mountain Range, in the State Of Washington USA. Almost 3 cubic kilometers of rock moved down the slope and the volume of the material was 2.8km cubed. This landslide buried 23km of the North Fork Toutle river with an average of 46m of rocks, soil and trees. Mount St Helen's Landslide Did You Know? Between 25 to 50 people are killed in landslides in the USA each year
The worst recorded landslide in Australia was in Tasmania in the 1960’s, 35 houses were destroyed in two adjacent landslides
In Jan 2011 over 400 people in south-eastern Brazil were killed because of landslide
A landslide earlier this year took place in the Philippines, leaving more than 100 people believed to be buried in the rubble of one of the harshly affected villages Websites: http://kids.discovery.com/tell-me/curiosity-corner/earth/natural-disasters/how-landslides-work
http://alphabetizer.flap.tv/index.php Glossary Abrupt: sudden or unexpected
Acoustic: pertaining to the sense or organs of hearing
Adjacent: close, adjoining
Agricultural: the science, art or occupation concerned with the management of soil
Analysed: examine carefully and in detail to identify causes, key factors, possible results
Chemistry: the science that deals with the composition and properties of substances and various elementary forms of matter
Cohesion: the molecular force between particles within a body or substance that acts to unite them
Collaborated: (collaborate) to work, one with another; cooperate
Debris: an accumulation of loose fragments of rock
Degradation: the wearing down of the land by the erosive action of water, wind or ice
Dense: having the component parts closely compacted together, crowded, close
Descends: to go or pass from a higher place; to move or come down
Distribute: (distributed) to spread, scatter or disperse through a space or over and area
Embankment: a bank or mound, sometimes raised to hold back water
Erosion: the process by which the earth is worn away due to water (flood), rain, wind, ice, glaciers, waves
Liquefaction: the act or process of making liquid
Rapid: moving or acting with great speed
Rupture: the state of being broken or burst
Sediment: mineral or organic matter deposited by water, air or ice
Stabilise: to make or hold stable, steadfast or firm
Terrain: a tract of land, especially as considered with reference to its natural features
Translational: change or conversion to another form, appearence
Turbulent: eing in a state of agitation; disturbed
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