AS Geography Edexcel- Unit 1 Revision Notes with case studies

Complete revision guide of all topics for unit 1, Includes case studies. 

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  • Created on: 25-05-13 10:29
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UNIT 1: World At Risk
Hydro-meteorological ­ caused by climate. Remember Hydro = Water =Floods ect.
Hurricanes , Storm surges
Thunder and hail storms
Rain wind blizzards
Drought -> Bushfires
Geophysical ­ caused by land processes
Volcanic activity
A natural Hazard- is a natural event which has the potential to cause loss of life injury, economic
damage, and environmental degradation.
Disasters: is the realization of hazards to cause social and economic impacts
Risk: is the probability of a hazard occurring and becoming a disaster as a result of deaths and loss of
When does a natural hazard become a disaster?
When a natural hazard has greater impacts, however it's hard to define. 1990 Swiss Re defined a
disaster as an event in which at least 20 people died!
Global warming is chronic (long term)
Hydro-met hazards are increasing ­ due to increased effects of global warming ­ largely
due to human activity
Geophysical hazards ­ hasn't been much change in frequency
However, may just SEEM to be more hazards ­ because of greater media coverage.
Numbers of deaths from disasters are DECREASING
Due to improvements in risk management...
Prediction ­ Improved technology, path of hazards can be predicted, helps people evacuate
Prevention ­ hazards can be prevented from becoming disasters (using sandbags to protect
against flooding)
Preparedness ­ educating people about what to do in case of a disaster, reducing the
number of deaths (e.g. Japan carry out `earthquake evacuation drills')

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UNIT 1: World At Risk
Rapid population growth ­ more people Global warming ­ more disasters occurring, higher
vulnerable to hazards severity
Increasing world poverty ­ poor people more El Nino ­ change global weather in an unpredicted
vulnerable way, making hydro meteorological hazards more
Exploitation of resources ­ e.g.…read more

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UNIT 1: World At Risk
Australia Bushfires
Occur every summer.
Significant property damage average 84 properties a year
There are fewer deaths now average of just 5 every year.
How have bushfires start?
o Carelessness outdoor BBQ, Cigarette stub
Lightning strike
Once started difficult to stop
3 Types of bushfire
Ground fires- Dry leaves and litter catch fire and spread through undergrowth
Crown fires ­ Fire spreads through treetops. Common in Gum trees.…read more

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UNIT 1: World At Risk
In December 2006 North London, was hit by a tornado that was so localised it only
effected a few streets. In just a few minutes roofs from cars were ripped off, trees
were brought down, and cars damaged or crushed by falling debris.
Occur as cold air moves rapidly south over warmer land. Air become warmer near
land. Air becomes lighter and starts to rise, making it unstable. Earth's rotation
causes the air to spin. Causes tornado.…read more

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UNIT 1: World At Risk
Low Middle Income country $5000 per capita
Plate boundary DESTRUCTIVE (Philippine subducts Eurasion)
o So it is at risk of volcaneoes e.g. Mount Pinatubu 2001 7000 deaths
o And Earthquakes, where plates have cracked e.g. 1990 7.8 magnitude in
Luzon 1,500 killed
Landslides Because of lots of rainfall over short time period on steep slopes can
be triggered by EQ. E.g. 2006 landslide buried whole village.…read more

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UNIT 1: World At Risk
Most African economies are heavily dependent on agriculture, farming is rainfed and
vulnerable to rainfall shortages. (Kenya rainfall expected to increase)
70% of Africans are farmers
Refugees from low lying coastal areas move to centre e.g. Lagos
60% of Africans live on coastal areas at risk of coastal erosion and flooding because
of sea level rise.…read more

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UNIT 1: World At Risk
Oceanic & Continental crust move together ­ MORE DENSE OCEANIC gets subducted
The oceanic crust is heated by friction ­ melts into magma
Magma is less dense than continental crust ­ rises to the surface (forming volcanoes)
The more dense plate gets subducted (oceanic or crust) ­ as plate moves under the other, it
can get stuck ­ pressure builds up ­ when too much pressure builds up ­ the plates jerk past
each other ­ EARTHQUAKE

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UNIT 1: World At Risk
Shift between cold glacial periods (last 100,000 years) and warmer inter-glacial periods (last
around 10,000 years)
Medium-Term Climate Change...
Climate switches from cool to warm every few 1000 years or so
Around 5000 years ago temperatures were 1-2 degrees higher than they are today
Short-Term Climate Change...…read more

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UNIT 1: World At Risk
Stretch ­ Orbit goes from a perfect circle to an ellipse every 96,000 years, changing the
distance from the earth to the sun, changing the amount of energy received from the sun
Tilt ­ Earth is tilted (called its axis), this changes between 21.8 to 24.4 degrees every
41,000 years. Tilt changes the amount of energy the different latitudes receive, changing
global climate.…read more

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UNIT 1: World At Risk
In the 1980's UK scientists discovered thinning in the ozone layer caused by CFC'S
Methane- minor gas but very effective in retaining heat.
CO2 sinks store CO2 (so it's not contributing to the atmosphere)
Biggest sinks are oceans (CO2 is dissolved in sea water) and plants (take in CO2 for
CO2 is released when trees are burnt (to make space for agriculture)
Causing ice to melt...…read more


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