The Restless Earth : GCSE AQA Geography A

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What is the thin outer layer of the earth called?
The crust
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State how the oceanic crust is different from the continental crust.
The oceanic crust is more dense/ continental is less dense. Oceanic crust is newer/ continental is older. Oceanic can be renewed or sink, Continental cannot sink or be renewed.
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What direction do destructive plates move?
They move together. ->
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What happens when two destructive plates meet?
1 oceanic + 1 continental = Denser oceanic sinks under lighter continental (SUBDUCTION). Oceanic melts to form MAGMA. 1 continental + continental = meet head on (COLLISION).
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What direction do constructive plates move?
They move apart to CONSTRUCT new land.
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What happens from two constructive plates move apart?
Cracks and gaps form between the plates, magma forces in cracks to the surface and dries to form new land. Over time, a volcano is formed.
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What direction do conservative plates move?
They slide past eachother at different ANGLES and SPEEDS.
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What happens when two conservative plates slide past eachother?
Due to different speeds/angles, they can get STUCK. As the plates attempt to move, there is a large build up of tension until a huge, jolting release of pressure which triggers an EARTHQUAKE.
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Name two landforms at Destructive plate boundaries
Fold Mountains and Ocean Trenches
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How are ocean trenches formed?
SUBDUCTION to form a deep section of the ocean (Ocean Trench)
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How are fold mountains formed?
SUBDUCTION if ocean trenches present, If not present then COLLISION. Sediment is deposited in the ocean trench and as the destructive plates push together, the sediment compacts and over time, fold mountains are formed.
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Describe how a Composite volcano is different to a Shield volcano.
Composite volcanoes have infrequent, violent eruptions, Shield volcanoes have frequent, non-violent eruptions. Composite have steep slopes, Shield have wide, gentle slopes. Shield emit no ash, runny lava, Composite emit thick ash and thick lava.
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Where do composite volcanoes occur?
Destructive plate boundaries
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Where do shield volcanoes occur?
Constructive plate boundaries
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Describe the use of farming in the Andes (or another fold mountain range)
Farming - Subsistence farmers grow crops on steep slopes, can provide for their families and produce a business by selling. Terraces create flat land to retain water. Llamas used for transport, meat, milk and their wool is used for clothes.
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Describe the use of mining in the Andes (or another fold mountain range)
Mining - provides more than half of perus exports. Yanacocha gold mine is largest in the world, daily dynamite blasts. Nearby town Cajamarca has grown from 30,000 to 240,000 people - bringing job sources and high crime rate.
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Describe the use of HEP in the Andes (or another fold mountain range)
HEP - Steep slopes that limit farming are an advantage for HEP. Can be dammed into wider valleys, relief encourages flow of water needed to generate electricity. Melting snow in spring increases water supply however not reliable all year round.
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Describe the use of Tourism in the Andes (or another fold mountain range)
Tourism - natural attractions i.e. volcanoes, lakes, glaciers. Remains of inca settlements and inca trail - cultural and historical. Local people can generate income from endorsing tourists to purchase their products.
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Describe the spread of volcanoes
Spread relates closely to plate margins. 'Pacific ring of fire' Pacific ocean prone to volcanoes.
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How can volcanoes be monitored?
Signs of impending eruption - earthquakes, swelling due to magma movement, increased sulphur dioxide emission.
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Describe the eruption activity of Mount St. Helens USA
Dormant for many years. March 1980, signs of impending eruption. 18th May 1980, eruption of 5.1 on richter scale.
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State the short term and long term effects of the eruption
Short term - Caused landslide, 57 died, ash clogged air conditioning, ash had good impact on soil, search + rescue. Long term - forest replanted, rebuilding of roads.
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What is a supervolcano?
Emits at least 1000km cubed of material, HUGE size. Large depressions cause calderas.
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State and talk about a supervolcano.
Yellow Stone supervolcano, Yellow stone national park USA. Evidence of magma shifting, caldera bulging. Eruptions occured at hotspots.
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What would be the effects of a supervolcano eruption?
Tens of thousands would die. Huge, hot cloud of gas would kill and destroy everything within tens of miles. Huge ash cloud would block out all daylight for whole continents which could trigger mini ice ages.
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Where does an earthquake begin?
In the FOCUS, deep in the crust.
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Deeper earthquakes cause...
less damage, less felt than shallow focus ones.
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What is the point above the focus called?
Epicentre - where the earthquake is most strongly felt
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State the two types of seismic wave
Longitudinal (up + down), Transverse (side to side)
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What do seismographs do?
record the shaking of a pen to identify the movement of the disaster
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What is the mercalli scale?
A scale used to measure by comparing and describing damage on a scale of I to VII.
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What is the richter scale?
A logarithmic scale used to measure the amount of energy produced from scientific recordings.
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How may an earthquake occur at a destructive plate margin?
The pressure from the subducting plate and melting may trigger strong earthquakes.
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How may an earthquake occur at a constructive plate margin?
Less intense than at a destructive plate margin, pressure of moving apart.
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Describe the Kobe, Japan earthquake and its effects.
17th january 1995. Phillipenes + Eurasian plates on Nojima fault. 7.2 on richter, tremors for 20 seconds. Wrecked city infrastructure, 6434 died, 40000 injured. no electricity/water. gas +water lines ruptured.
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Describe the responses to Kobe
Hospitals struggles, Motorola provided free phone lines, Major retailers provided essentials. Railways 80% operating within a month.
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Describe the Sichuan, China earthquake and its effects.
12th may 2008. Indian + Eurasian plates on Longmenshen fault. 7.9 on richter scale, lasting 120 seconds. 374,000 injured, 69,000 died. 80% of building collapsed. Middle school collapsed. Landslide blocked roads. $75 million damage.
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Describe the responses to Sichuan
Access to some areas was impossible. Search + rescue helicopters. Army troops called in. Lack of food + water. 1 million temporary homes built.
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State the 3 Ps
PREDICTION - forecasting based on current knowledge. PROTECTION - building to appropriate standards. PREPARATION - organizing drills.
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What is a Tsunami?
Usually triggered by an earthquake when the crust shifts. Huge displacement of water above shifted crust. Crests 200km apart, water at 800kmph. As approach shore, height increases, wavelength shortens.
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Describe the effects of the Indian Ocean tsunami.
26th December, 2004. Indo-australian subducting below Eurasian. 9.1 earthquake on richter scale. 220,000 died, 650,000 seriously injured. Public buildings wiped out.
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Describe the responses to the Indian Ocean tsunami.
Immediate donations from international community - food, water, tents. £375 million donated by british charity. Action Aid built graves to bury the dead to prevent disease. 20,000 homes built for 100,000 people. Tsunami Warning system set up.
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Other cards in this set

Card 2

Front

State how the oceanic crust is different from the continental crust.

Back

The oceanic crust is more dense/ continental is less dense. Oceanic crust is newer/ continental is older. Oceanic can be renewed or sink, Continental cannot sink or be renewed.

Card 3

Front

What direction do destructive plates move?

Back

Preview of the front of card 3

Card 4

Front

What happens when two destructive plates meet?

Back

Preview of the front of card 4

Card 5

Front

What direction do constructive plates move?

Back

Preview of the front of card 5
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Comments

sam

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This is extremely helpful! Thank you so much! 

Good Luck tomorrow :) 

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