Question 1:
The Restless Earth
Inner Core
Solid Iron and Nickel- over
5000degrees
Outer Core
Liquid Iron and Nickel
Mantle
Molten rock- moving 1800- 3500
degrees
Crust - Thinnest layer
Plate Boundaries
Examples of Plate Margins
Nazca Plate and South American Plates
Destructive
Conservative
North American and Pacific Plates
Constructive
South American and Atlantic Plates
Types of Crust
Oceanic
Continental
Newer – most are less than 200 million
years old.
Can be renewed forming new crust and
destroyed
Older – most are over 1500 million years old
Denser
Can sink
Less dense
Cannot sink
Cannot be renewed or destroyed
Destructive Plate Margins
Convection currents in the mantle cause plates to move together. If one plate is
made from oceanic crust and the other from continental crust, the denser oceanic
crust sinks under the lighter continental crust in a process known as subduction.
Great pressure is exerted and the oceanic crust is destroyed as it melts due to
friction to form magma.
Key Words
Subduction: the sinking of oceanic crust at a destructive margin.
Collision: the meeting of two plates of continental crust. They are both the same
type so they meet ‘head on’ and buckle.
Constructive Plate Margin
When plates move apart, a constructive
plate boundary results. This usually
happens under the ocean. As the plates
pull away from each other, cracks and
fractures form between the plates where
there is no solid crust. Magma forces its
way up into the cracks and makes it way
to the surface and spreads out over a
wide area to form shield volcanoes. In
this way new crust is formed.
Conservative Plate Margin
At conservative plate margins, the
plates are sliding past each other.
They are moving in similar (though
not the same) directions, at slightly
different angles and speeds. As one
plate is moving faster than the other
and in a slightly different direction,
they tend to get stuck. Eventually the
build- up of pressure causes the
plates to be released, causing them to
jolt. This sudden release causes an
earthquake. At conservative plate
margins new land is neither created
not destroyed.
Landforms found at plate margins/boundaries
Ocean Trenches
Ocean trenches form some of the
deepest parts of the ocean.
They are found along destructive plate
margins where the oceanic crust is
pushed under the Continental crust.
Subduction
Young Fold mountains
Young fold mountains are the highest
areas in the world. They include ranges
such as the Himalayas, the Rockies, the
Andes and the Alps. Older fold mountains
are less high due to erosion. Examples of
these are the Cumbrian Mountains in the
UK. Collision
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Rivers flow sediment into the oceans between plates
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Sediment forms layers on the ocean floor.
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The Plates push together causing the sediment to be compressed. Rivers
continue to add more sediment.
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Sediments forms rocks that begin to fold upwards.
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This creates Young fold mountains.
How do people use an area of Fold mountains?
The Himalayas.
Nepal, Asia.
Home to 29 million people. On the Border between India and China. Home of Mount
Everest.
Problems experienced in Fold Mountain areas.
Mountainous rugged terrain makes it difficult to build or farm on the land.
Difficult to communicate between areas due to the steep relief and interference with
cell phone transmissions.
Tourists to the area leave large amounts of litter such as oxygen masks, tents and
even dead bodies because it is hard to clean up in the tough conditions.
It is difficult to provide modern services such as fresh water and electricity due to the
difficulties constructing pylons and pipelines.
Solutions
Solutions - Tourism
Tourism provides jobs for local people as Sherpa guides carrying the equipment of
climbers. Earns £1600 for 60days.
Also provides an income for the government who sell licenses at £50,000 for a team
of 7 climbers.
Mountains including Everest (8,800m) are vital attractions that bring extreme
tourists and explorers to the area.
Solutions- Hydroelectric power
Only 30% of Nepal has electricity. HEP enables Nepal to dam off rivers in
mountainous areas to provide sustainable energy to help develop the area.
Solutions - Farming
76% of Nepalese are farmers. The steep relief makes rice farming difficult, so slopes
are terraced to make the growing of crops easier.
Farmers are mainly subsistence farmers and rely on growing crops for their own
families to survive.
Crops are mixed with goats and cattle due to poor soils.
Government is encouraging production of cash crops to boost exports and help the
economy.
By increasing the amount of land for farming it has increased deforetation.
Solutions - Communications
By building cell towers on the peaks of mountains it enables point to point
communications in difficult terrain.
Building roads that wind to follow the relief, ski lifts and tunnels, it is easier to
communicate between areas.
Solutions - Mining
Mining only accounts for 0.5% of nepal's GDP at present though surveys are being
carried out to locate rich veins of rare earths/ gold and diamonds.
Features of Composite and Shield Volcanoes
Composite Volcanoes
Shield Volcanoes
Distribution of Volcanoes
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Volcanoes are an example of a
natural hazard. Their spread
relates closely to plate margins.
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The area around the Pacific Ocean
is especially prone to volcanoes
and is known as ‘the Pacific Ring of
Fire’.
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Occasionally active volcanoes are
found away from plate margins at
Hot spots.
Case Study of a Volcanic Eruption
Soufriere Hills, Montserrat, 1997
Effects of the eruption
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Pyroclastic flow surprised and killed 19 people in a 500 degree burning
firestorm.
Half of Montserrat became uninhabitable.
Homes and farms were covered in ash and destroyed. People were left
homeless and forced to evacuate.
Tourists stopped visiting the island due to fear and the devastation destroying
tourist industry.
Most of the islands infrastructure was destroyed including the airport and the
port located in Plymouth.
Capital Plymouth was buried under a giant mudflow - lahar, as rain mixed with
ash from the eruption.
Quartz in the ash led to an increase in health problems such as silicosis of the
lungs.
Responses to the eruption - Immediate
Response to the eruption - Long term
8500 people were evacuated off the
By 2010 1500 people had returned island to places such as the UK for safety. increasing the population to 5000 people.
British government was forced to protect
the territory providing millions of pounds
of aid for food, water and emergency
shelter.
Many younger people left and never
returned, this had led to an imbalance
with the population made up of mainly
older people. This will create major
problems in the future.
An exclusion zone was setup around the
volcano with the population forced to
evacuate to the north of the island.
The British government built a new port
in the north at Little Bay to bring in
supplies and restart the economy.
The Capital Plymouth was evacuated to
avoid Ash and mudflows.
Monitoring Future Eruptions
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Scientists will use tilt meters to measure the shape of the volcano and to
detect changes.
Measuring sulphur dioxide emissions enables scientists to detect a build up of
gas prior to an eruption.
Using seismographs means that they can detect tremors that could signify an
eruption is imminent.
What is a supervolcano?
Size
Shape
A supervolcano is a mega volcano that
erupts at least 1,000km³ of material.
Have large depressions called Calderas
Very wide- Yellowstone is 64km
Have steep mountain ridge around them
How do They Erupt?
The effects of a super volcanic eruption e.g Yellowstone
The likely effects of an eruption
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INITIAL EFFECTS: the clearing of any tourists in the national park and any one
in a 100 mile radius. The park would be closed. The volcano would erupt fine
materials, shooting them up 80,000 feet into the air.
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Pyroclastic flows would spread about 50-100 miles, killing and destroying
everything in its path.
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Small earthquakes would shake the ground causing damage. A hurricane of
ash is likely and rock as hot as 1200 degrees would come out of volcano.
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Parts of NW America would be completely destroyed. The worst hit area would
be Montana.
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There would be lots of ash (1000 times that of Mt. Helens) and buildings would
be covered with up to 30ft of ash.
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The ash made of small shards of glass would destroy humans and animals
lungs. Masks would have to be worn. If the ash rose aero planes would have to
be grounded and any flying could risk the engines failing midflight. Growing
crops would become difficult too.
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Worldwide travel would cease and day would be turned to night. It would alter
the climate and make everywhere much colder. Up to 15 degree drop in global
temperatures.
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The ash would stay in the atmosphere for up to 6 years and worldwide trade
would be affected too.
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Sunlight would be blocked out leading to loss of crops, hunger, famine and
enormous loss of life. Up to 1 billion people would die.
What are Earthquakes and where do they occur?
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The place where earthquakes begin, deep within the earth’s crust is called the
focus; deep-focus earthquakes cause less damage and are felt less than
shallower ones.
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The point above the focus where the earthquake is most strongly felt is called
the epicenter.
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Radiating out from the epicentre are shockwaves / seismic waves.
Measuring Earthquakes
The Richter scale
The strength of an earthquake is usually given according the Richter scale.
Measured using a seismograph as it happens.
There is no upper limit and the logarithmic scale means that there is a 10 times
increase in power between number.
1>2 = 10x more powerfu
1>3=100x more powerful
The Mercalli Scale
Measured using Scientific observations after
the earthquake has happpened.
Uses Roman numerals on a scale of 1-12
I -XII
It measures the power and effects of the
Earthquake.
Examples
I = Only felt by scientific instruments
V = Windows would break
XII = Everything would be destroyed
Response to an Earthquake - Rich Vs Poor
Haiti - Poorer Country
Chile - A richer Country
Haiti is in the Caribbean
Chile is in South America.
Ranked 143rd for GDP.
Ranked 46th for GDP.
Very poor- hit 12 Jan 2010 by a 7.0
earthquake.
Rich - hit 27 February 2010 by a 8.8
Earthquake
Primary effects
Haiti - Poorer Country
Chile - A richer Country
220,00 killed, 300,000 injured.
500 killed, 12,000 injured.
Main Port (Port au Prince) was destroyed
cutting off Haiti
500,000 homes damaged,
Several bridges and roads destroyed.
1.3 million left homeless after 1million
homes destroyed
Secondary effects
Haiti - Poorer Country
Chile - A richer Country
2 million left without food and water.
Chile lost power for up to 9 days.
National emergency.
Hit by a small Tsunami
Looting became a problem as people
tried to survive.
There was a chemical fire in Santiago.
Aid could not reach Haiti and Cholera had
taken hold by November.
People were forced to live in tents.
Immediate responses
Haiti - Poorer Country
Chile - A richer Country
Slowed and hampered by damaged port
and roads.
Requested help from other countries- aid,
medical teams.
UN sent troops and food for 2 million
people.
10 days later 90% of homes had
electricity
Bottled water and purification tablets
were given to survivors. US divers set
about repairing the port.
$60million raised in a national telethon to
help those affected.
Repaired important roads within 24hrs to
transport aid and rescue machinery.
Long Term Responses
Haiti - Poorer Country
Chile - A richer Country
Reliant on overseas aid indefinitely.
New homes were to be built but would
costs $billions.
Required massive investment to restore
water and electric services.
1 month after the quake, the government
began rebuilding and repairing 196,000
homes.
Used its huge copper reserves to pay for
the reconstruction efforts.
Protection and the future
Haiti - Poorer Country
Wasn't prepared- too poor and no recent
earthquake.
Overcrowded with poorly built houses
that easily crumbled.
Government was too poor to prepare.
Chile - A richer Country
After quake in 1960 Chile had prepared.
Education and training taught people to
drop, cover and seek safety.
Government runs regular disaster drills to
prepare
Case Study: Indian Ocean Tsunami 2004
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Cause
When 2 plates collide and lock out at sea.
Pressure builds up between the plates due to friction.
Pressure is released causing plates to jolt.
This causes the water above the plates to be displaced.
This creates a massive wave Tsunami
The Tsunami travels outwards in all directions at over 800kmph.
As the wave reaches the shore it gets shallower causing it to slow down.
This causes the wave to rise by 10-20m and then break.
Effects
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Hit by 9.0 Earthquake that created Tsunami in the Indian Ocean that hit 12
countries.
300,00 people killed by the wave including 236,000 in Indonesia.
Sumatra was the closest island to the epicenter. 70% of the coastal population
was missing or killed.
400,000 people lost their jobs as coast was ravaged. Farms destroyed, fishing
boats smashed and the economy collapsed in a matter of minutes.
Tourist resorts hit with 1700 killed. Led to collapse of tourist industry through
fear and loss of resorts/ hotels.
Arable farmland was contaminated by salt water that killed off the crops.
Responses - Immediate
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Clean water, food and shelter were sent by an international charity campaign,
along with key countries such as the United States.
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$7 billion dollars was donated worldwide with $330million coming from the UK.
The money was used to begin cleanup operations and reconstruction of the
devastated communities.
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The United Nations provided food for over 1.3 million people to fend of
starvation and help the area to recover due to loss of farm land from salt
water contamination.
Responses - Long Term
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A tsunami warning system was setup in the Indian ocean to send
messages to all neighboring countries.
Bells, megaphones and speakers have been installed in coastal destinations to
provide warnings and to stave off future disasters.
Mangrove swamps were re-grown to act as a natural barrier along the coast to
absorb the impact of future tsunami's.
Mangrove swamps act as a breeding ground for fish and by restoring them it
created new fishing jobs.
Convection Currents
Heat from the core
causes the magma in the
mantle to warm and rise.
As the magma reaches
the crust it is buffered
and causes the plates to
move
As it cools the magma
returns to the core to
repeat cycle.