AS Level Edexcel Geography THE WORLD AT RISK NOTES

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Geography ­ the world at risk
Hazards and disasters
A natural hazard is a natural event or process which affects people e.g. causing loss of
life or injury, economic damage, disruption to people's lives or environmental
degradation.
For a natural event to become a hazard, it has to involve people.
Types of hazard:
Hydro-meteorological those caused by running water and its processes (hydro) and
those associated with or caused by weather patterns (meteorological). E.g. floods,
hurricanes and drought.
Geophysical those caused by earth processes. There are two types:
Internal earth processes (tectonic) e.g. earthquakes and volcanoes
External earth processes (geomorphological) e.g. landslides or rockslides
When does a natural hazard become a disaster?
Dregs model defines disasters as a matter of scale, simply bigger than a natural hazard.
Whether a hazard becomes a disaster can depend on how vulnerable people who are
exposed to it are.
cause of
hazard
hazard
conservative margin when two plates move alongside eachother. Gives major
earthquakes e.g. San Andreas fault. Sudden movements from
pressure.
destructive margin occur when oceanic crust collides with plates of continental
crust. Collision zone is subduction zone. Continental above
oceanic. Pressure submerges plate. Descending plate is
burned up to form lava so earthquakes occur. Fold mountains.
E.g. Montserrat.
constructive margin when plates move away from eachother, dragged by
convection. Magma rises to form oceanic crust. Volcanos and
earthquakes e.g. Iceland.
collision margin where plates of continental crust move towards eachother.
Edges buckle up to form mountains.
tsunamis undersea earthquakes. Can be caused by seismic events. One
plate slips under another water is displaced vertically. Creates
powerful waves.
landslides mountainous places prone. After abnormal rain and/or seismic
activity. Human factors e.g. deforestation/building on hills.

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Global warming
increases.
Describing the distribution of earthquakes/volcanoes/slides
Earthquakes greater concentration at plate boundaries e.g. Eurasian plate. Pacific ring of
fire. Mid Atlantic ridge.
Volcanoes found along plate boundaries. Weaknesses in earth's crust.
Slides located in north America/Europe/new Zealand. Mainly in mountainous regions.
Distribution and cause of hydro-meteorological hazards
Hurricanes are just above and just below the equator between the tropics. Greatest
activity over oceans. In warmer regions.
Drought/wildfire located in the tropic of cancer/Sahel/Australia/north America.…read more

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As a result, some of the warm water piled up in the west slumps back down to
the east, and not as much cold water gets pulled up from below. Both these tend to
make the water in the eastern Pacific warmer, which is one of the hallmarks of an El
Niño. The warmer ocean then affects the winds - it makes the winds weaker, heating
the water.…read more

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Mountainous. Conflict.
Ground shaking.
Capacity to Expensive rebuilding. Aid/funding. Aid ­ very remote so no aid. 500,000
cope people. Demand for tents. Conflict
weakened response to capacity.
Death toll Death toll 90,000. Health centres Farmers lost harvest. Schools destroyed.
destroyed. Chemical factory. Loss of Infrastructure ­ regulations.
facilities. Death toll 73,000.…read more

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Among the world's wealthiest countries.
Plate tectonics
San Andreas fault where Pacific plate moves north-westwards past the north American
plate. The two move in the same direction causing friction. Called a conservative
boundary. Fault line between.
1906 San Francisco earthquake
8.2 on Richter scale.
1989 Loma Prieta earthquake
Magnitude 7.1. After shock magnitude 5.2. 63 people died and 13757 injured. 1018 homes
destroyed and 23408 damaged. 366 businesses destroyed and 3530 damaged. Repairs
US$6 billion.
1994 Los Angeles earthquake
Magnitude 6.7. thousands of aftershocks.…read more

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Sets
up
small
conve
ction
curren
t
3) Earth'
s
rotatio
n
cause
s
rising
air to
spin
4) The
faster
the
spin,
the
more
air
likely
to
`touch
down'
on
surfac
e,
formin
ga
tornad
o.
low depressions
pressure
1) Air 1) Cold air from polar regions
warm meet warm air from tropics
s up 2) Warm air sucked up ­ cold
molec air sucked behind.
ules ­ Anti-clockwise. Warm
furthe front/cold front.
r apart 3) Warm sector climbs.…read more

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Low warm sector ­ occluded
press front.
ure at 4) Cold air replaced warm.
surfac Temperature evens out.
e 5) Storms
3) Rising
air
draws
up
moist
ure ­
cools
and
conde
nses
4) Cloud
s form
= rain
5) Storm
s
occur
Droughts
Drought an extended period of low/absent rainfall relative to the expected for a
region. OR. When evapotranspiration exceeds precipitation and soil moisture is depleted
to an extent that crops and much natural vegetation cannot grow.…read more

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Natural greenhouse effect:
Enhanced greenhouse effect:
Natural and human causes:
Milankovitch cycles and sun spots plate tectonics Ice-albedo effect
sunspots work in cycles. Sun's existence of land mass at the snow and ice form integral
energy varies over short periods. poles/surrounding part of regulating earth's
Affects global temperature. The encourages ice sheets. temperature. Albedo ­ the
earth's orbit varies every 100,000 Prevents warm ocean ability for ice to reflect solar
years with changes in earth's axis currents reaching. Snowfall energy.…read more

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This CFCS e.g. in spray
(precipitation from clouds) causes environmental cans/refrigerators
problems. Vegetation helps Rice production, burning
regulate the balance.
vegetation, coal mining,
livestock flatulence
Fertilisers, fossil fuels,
synthetic chemicals.
ocean circulations e.g. ENSO
warm/cold water. Undersea
circulations. El Niño disrupts
climate. Atmospheric wind
patterns worldwide.
EVIDENCE FOR CLIMATIC CHANGE - Climate change and its causes
Three timescales:
GEOLOGICAL (LONG TERM)
HISTORICAL (MEDIUM TERM)
RECENT (SHORT TERM)
Long term
ice cores (carbon dioxide levels/oxygen Greenland and Antarctic ice cores.…read more

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Show near surface
air temperatures. Show warming. pH
levels have changed. Thermal expansion
ice response glaciers change in response. Look at
photos/maps/paintings to see direct
differences in glacial positions.
astronomical forcing Milankovitch theory of earth's orbit. Tilt
leads to change in amount and distribution
of sunlight.
The Arctic ­ case study of the impacts of global
warming
The politics of the Arctic
The region is a zone of increasing resource exploitation,
and potential conflict, as fossil fuels and minerals run out.…read more

Comments

Grace Hannaford

Really detailed and helpful notes thank-you!

SHAHREZ

thankyou 

10dhothn

Do you have notes on rebranding/coasts? 

Jessieturnbull2

Wow thank you so much

YaAlreeet

Anyone else on a skits for this exam?

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