Hazards
- Created by: GeorgiaJackson
- Created on: 04-11-14 19:52
Describe a divergent boundary
Divergent is when the 2 plates move away from each other and form new crust
It is formed by low level eruptions
Describe a transform boundary
The plates move in direction against one another. They move in different speeds and it causes a build in tension.
Describe a convergent boundary
This is where the plates come together and the oceanic gets stuck beneath the continental in which builds up tension and causes and earthquakes. Or the crust is destroyed forming new crust
What is a natural hazard
A dangerous phenomenon that my cause loss of life , injury or other health impacts, property damage, loss of life and services, social and economic disruption or environmental damages.
Describe the natural hazard risk equation
The equation can be used to determine the level of risk a population will face. This can create a statistical impact of the size of the impact of an event.
V and c can alter between countries . In MEDCS they are less vulnerable to hazards and have a higher carrying capacity due to the amount of money they have and also their improved infrastructure. Where as in lEDCs they are more vulnerable and have a lower carrying capacity, they have less money to deal with the hazard and the infrastructure does to have building regulations
Hazard management strategy
Post disaster
Response - the effectiveness depends on education , training and experience or emergency recovery reposes
Recovery - action to assist communities to return to predisaster conditions
Redevelopment- action to manage economic loses, there should be a long term link between national economic activities
Pre coaster
Prevention- action to reduce severity of impact
Mitigation- action to minimise property and economic damage
Preparedness- action to increase speed and efficiency response
Draw the disaster impact cycle
Explain prediction of earthquakes
Prediction is highly unreliable. For example we can measure the movement of the ground but small quakes are not always an indication that a big one is around the corner
We can also try to measure stress levels but still this is not always effective ( San Andreas fault reference)
We also can look for a historical pattern
How can we prepare for an earthquake
In California in the USA it is prone to serious earthquakes. To become prepared they have introduced the following to reduce the loss of life
Practice drills
Evacuation plans
Disaster planning- planning refugee camps , medication, water purification and search and rescue
All of these factors are influenced by money
How can you prevent damage
Damage can be prevented by the construction of buildings. Firstly the buildings must have enforceable regulations. However these are largely ignored in LEDCS due to bribes and corruption
Secondly the design is important. They must be solid steel structures with wide bases and deep foundations. Some also may have counter weights which allow the building to sway
How can earthquakes be predicted
Monitoring and prediction is very good - mount st Helens
We can monitor ground temperature ( as the magma rise the temperature rises), soulful dioxide and hydrogen chloride. As we look at the deformation and seismic waves.
How can we prevent damages
Hazard zoning areas
Define mass movement
Mass movement is the downhill transfer of slope material. It includes any large scale movement of the earths surface that it accompanied by a movie agent such as a river glacier or ocean
Describe flows
Fastest flowing
They are characterised by internal movements of individual grains within the flow itself. Hey internal flow can be fast and chaotic if it originates from a steep slope or contains a lot of water. Or grain movements can be very slow and somewhat predictable if the slope surface is very gradual in its angle
Describe falls
These are fast moving rock falls in which pieces of rock travel down a slope. The size of the rock that falls can vary. An example of a rock fall is Pennington point in South East Devon in which receives continuous coastal exposures from the river otter.
Describe a translation slide
A down slope movement of material that occurs along a distinctive surface of weakness such as a fault or join bedding plain. If the slip is straight then it is termed transnational
Describe rotational slip
Characterised by the movement along up failure surface. The upper unit of the slump is typically tilted back and surface water may be retained in the depressed zone. It is normally found in uniform relatively weak material e.g. Clay.
Describe a creep
A creep takes many years and can form terraces in the ground. It occurs when sediment expands and individual particles are lifter up at right angles to the slope. Sediments can expand when they freeze , are heated up or get wet. When the sediments shrink the particles fall straight back down
Define the following
Shear strength- internal resistance of a body to movement
Shear stress- the force acting on a body that causes it to move down a slope
Anything that reduces the strength and increases the stress causes slope failure
What increases mass movement
Construction of infrastructure
Heavy precipitous puts weight on the land
Snow melt due to global warming
Roads and traffic put weight on land
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