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EMS Geography GCSE Revision FLASH CARDS: Unit 2 – Tectonic Landscapes

EMS Geography GCSE Revision: Question(s) Answer(s)

TECTONIC LANDSCAPES

Define the terms: (a) location (b) characteristics(c) distribution

Location – place where something can be found

Characteristics – the main features of the item

Distribution – the pattern of where something is on Earth (look for trends and anomalies – do not fit trend)

EMS Geography GCSE Revision: Question(s) Answer(s)TECTONIC LANDSCAPES

Describe the global distribution of earthquakes and volcanoes.

- Both earthquakes & volcanoes occur in long narrow bands - often following the edge of continents (e.g. West Coast of North & South America) - Largest band of volcanoes are found along the Pacific Ring of Fire (around the Pacific Ocean) - Earthquakes and Volcanoes are also found together in bands in the middle of Oceans (e.g. Mid-Atlantic Ridge) - NOT all follow the same pattern:some volcanoes are found in isolated clusters - e.g. Hawaiian Islands - middle of Pacific Plate) – known as a hot spot;some earthquakes occur away from plate boundaries – intraplate earthquakes – e.g. Gujurat, India earthquake 2001.


What is the structure of the Earth?

The Earth is made up of four distinct layers:1. The inner core is in the centre and is the

hottest part of the Earth. It is solid and made up of iron and nickel with temperatures of up to 5,500°C.

2. The outer core is the layer surrounding the inner core but is liquid.

3. The mantle is the widest section of the Earth. It has a thickness of approximately 2,900 km. The mantle is made up of semi-molten rock called magma. In the upper parts of the mantle the rock is hard, but lower down the rock is soft and beginning to melt.

4. The crust is the solid outer layer of the earth which is broken into 7 large plates. It is a thin layer between 0-70 kms thick. The crust is the solid rock layer upon which we live.

There are two different types of crust: continental crust, which carries land, and oceanic crust, which carries water.



TECTONIC LANDSCAPES

Give three differences between oceanic and continental crust.

Oceanic crust is 5-10km thick (Continental 25-100km)

Oceanic crust is denser (heavier) than continental crust

Oceanic crust is constantly renewed and destroyed (continental is permanent and cannot be destroyed.


What are convection currents?

Convection currents – a movement of heated material (magma) up through the mantle from the Earth’s core to the crust.As the magma cools it sinks down to be reheated.


What are hotspots?

A hotspot is a plume (column) of magma (hot molten material) rising from the mantle. Usually occur under oceans.This magma is lighter than the surroundings and rises - erupting at the surface where the crust is thin, creating a volcano (and eventually a volcanic island) They are fixed within the mantle & as the crust moves over the top - a chain of volcanic islands is left behind (e.g. Hawaii)


What are the different types of plate boundaries?

Convergent (destructive) plate boundary – the plates move towards each other and destroy the crust

Divergent (constructive) plate boundary – the plates move away from each other and create the crust.

Conservative plate boundary – the plates move past each other – crust is not made or destroyed.

EMS Geography GCSE Revision: Question(s) Answer(s)TECTONIC LANDSCAPES Convergent (destructive) plate boundary where


What type of boundary is shown in the diagram below? -

Outline what happens here.

an oceanic (e.g. Nazca) and continental (e.g. South American) plate move towards each other due to convection currents. - Denser (heavier) oceanic crust is subducted below the continental plate, forming a deep ocean trench - Heat from the mantle & friction between the plates causes the oceanic plate to be destroyed - As the plate melts, magma forms and due to the pressure and the heat is forced to rise to the surface - Magma erupts at the surface as lava, forming a composite cone volcano - Fold mountains (e.g. Andes) are created due to the impact of collision (earthquakes may occur)


Name the characteristic features at A, B, C and D

A - Subduction Zone

B - Oceanic Trench

C - Island Arc

D - Volcano


Explain what happens at a convergent plate boundary where two oceanic plates meet.

- Plates move towards each other due to convection currents. - Cooler and denser (heavier) oceanic crust is subducted, forming a deep ocean trench - As the plate descends it deforms, creating frequent earthquakes – known as the Benioff zone.- Heat from the mantle & friction between the plates causes the denser oceanic plate to be destroyed - As the plate melts, magma forms and due to the pressure and the heat is forced to rise to the surface - Magma erupts at the surface as lava, forming a volcano - E.g. Philippine Plate moving west & subducting under the Eurasian plate (forms the Ryuku Islands - nr Japan)



TECTONIC LANDSCAPES

Outline the formation of fold mountains.

Fold

mountains form at continental-continental convergent boundaries (can also occur at oceanic-continental). - At these boundaries as the two plates meet, the force of the collision causes folding and faulting to occur - This results in uplift of rock and sediment squeezed during the collision. - The result is fold mountains such as the Himalayas (Indian plate colliding with Eurasian)- There are no volcanoes as the crust is not being melted and subducted- Earthquakes occur due to the continued impact of the collision.

EMS Geography GCSE Revision: Question(s) Answer(s)TECTONIC LANDSCAPESExplain the processes at a divergent plate boundary

- Two plates move away from each other due to convection currents - As the plate move apart, pressure causes the crustal rocks to fracture and a gap and ridge (mid-oceanic ridge) form – e.g. Mid-Atlantic ridge- Magma rises to fill the gap, volcanoes form and new crust is created (usually found under the ocean, this is known as sea floor spreading). - As magma builds up, volcanic islands form above the surface of the ocean (e.g. Surtsey, Iceland) - Often have earthquakes associated with these boundaries.


Name the features found at an oceanic-oceanic convergent boundary.

1. Oceanic Trench 2. Subduction Zone 3. Volcanic Islands 4. Island arc


Name the features found at an oceanic-continental convergent boundary.

1. Oceanic Trench 2. Subduction Zone 3. Fold Mountains 4. Volcanoes



TECTONIC LANDSCAPES

Explain what happens at a conservative (transform) plate boundary

Also known as passive plate boundaries.- Two plates slide past each other, without creating or destroying any land.- As they move past each other they often get stuck, building up great pressure until finally they jolt past each other. This sudden movement is what causes violent and frequent earthquakes. There is no subduction = no volcanoes.- The best-known example of a conservative plate boundary is the San Andreas Fault, where the North American (1cm per year) and Pacific (6cm per year) plates are actually moving in the same direction, but at different speeds.


Name an example of: - Fold Mountains - Oceanic Ridge - Islands created by a hotspot - Convergent Boundary - Transform Fault

Fold Mountains - Himalayas or Andes

Oceanic Ridge - Mid-Atlantic Ridge

Islands created by a hotspot - Hawaiian Islands

Convergent Boundary - Nazca and South American Plates meeting

Transform Fault - San Andreas Fault (California) - also known as a conservative boundary


Define the following key terms... 1. Epicentre 2 Focus3. Magnitude

1. Epicentre - this is the point on the surface directly above the focus of an earthquake - the most damage to buildings and infrastructure (e.g. roads, electricity) often occur here

2. Focus - this is the point underground where the earthquake starts - it is here where the greatest release of energy occurs – shock waves move out from this point

3. Magnitude - the strength of an earthquake, reflecting the amount of energy released.



Give four differences between the Mercalli scale and the Richter Scale.

1. Mercalli scale measure damage caused by an earthquake whereas the Richter scale measures the magnitude 2. Mercalli scale measurements are based on observations of damage to buildings whereas the Richter scale is based on scientific measurements from a seismometer 3. Mercalli scale is subjective(based on opinion) - the Richter scale is quantitative (objective) using a logarithmic scale = each level is 10x greater than previous one.4. The Mercalli scale is not useful in uninhabited areas (few visible effects). Richter scale can be used to measure earthquake vibrations anywhere (if seismometer in place).


Outline the economic reasons for people continuing to live in areas prone to volcanic activity.

Exam tip: You must know a range of place-specific examples

- Fertile soils - provide rich opportunities for growing crops to be sold (e.g. Coffee grown on the slopes of volcanoes in Columbia).

- Important source of cheap geothermal energy e.g. Iceland 28% of electricity from geothermal sources.


Outline the social reasons for people continuing to live in areas prone to volcanic activity.


Perception – inertia – believe there is very little risk of a volcano happening e.g. Mt St Helens (1980) many refused to evacuate as had been dormant for 123 years.

Poverty in LICs – many people cannot afford to move e.g. Mt Merapi (Indonesia) is one of the world’s most active volcanoes though 70,000 people live in vicinity.



TECTONIC LANDSCAPES Outline the environmental reasons for people continuing to live in areas prone to volcanic activity.


The area around the volcano is very scenic and many tourists visit e.g.:- Iceland with attractions like Blue Lagoon, Strokkur Geysir - provides 5000 jobs and accounts for 5% of Iceland's earnings & - -- Indonesia: Popular active volcanoes are the 2,329-metre (7,641 ft) high Mount Bromo in the East Java province with its scenic volcanic desert around the crater


Outline the economic reasons for people continuing to live in areas prone to earthquake activity.


Many e/q prone areas are also popular tourist areas - therefore people prepared to take the risk because of jobs e.g. Iceland – many jobs related to showing tourists the earthquake areas.

People have jobs in the mining industry in e/q areas e.g. Copper mine in Chile. In 2007, 2 people killed in mine during an earthquake, though local people think risk is acceptable because they have a job.


Outline the social reasons for people continuing to live in areas prone to earthquake activity.


- Technology in HICs- increased confidence due to earthquake proof buildings and disaster management plans in place e.g reinforced foundations / counterweights such as those in Japan and California (e.g. Transamerica building - San Francisco) - also advanced rescue equipment and detailed disaster plans in place.

- Perception in LICs that there is little risk - inertia


Outline the environmental reasons for people continuing to live in areas prone to earthquake activity.


Some earthquake areas are very scenic and have been developed for wealthy people e.g. Malibu, a very expensive coastal resort, has developed on the California coast of the USA.

Most of the country is tectonically active (e.g. Japan)

EMS Geography GCSE Revision: Question(s) Answer(s)TECTONIC LANDSCAPES Prediction:

Forecasting: - Seismometers can measure movements and may


Explain how the effects of earthquakes can be reduced through prediction and prevention


predict when likely to take place e.g. USGS post earthquake activity / stresses within one minute on their website. - Study of stress in geology (rock type). e.g. Los Angeles basin (prone to earthquakes) made of coastal sediment = very weak.- Hazard mapping using historical data.Note: Prediction = very difficult, as earthquake is a sudden movement.

Prevention:Building design and defence – earthquake proof new and retrofitting older buildings to make them safe – reinforced foundations; automatic shutters on windows; interlocking framework. E.g. San Francisco airport has columns standing on 1.5 metre ball bearings which allow the building to sway with an earthquake.Education and planning – Japan has an annual earthquake practice drill such as ‘duck, cover and hold on’ on 1st Sept for schools and businesses based on a 7.3 magnitude scenario. In the USA, (F)ederal (E)mergency (M)anagement (A)gency provides packs on how to prepare for earthquakes as well as information on their website.


Explain how the effects of volcanoes can be reduced through prediction and prevention


Prediction:Forecasting: - Eruption of Mount St. Helens (May 1980) was predicted due to the movement of tiltmeters placed on its slopes.- Gases are monitored e.g. Mt Pinatubo predicted due to change in gases (SO2) coming out of the volcano- Remote sensing: infrared satellite images record changes in the shape of the volcano

Prevention:Building design and defence – lava flows cooled with water slow movement; diversion channels can also be built around villages.Mt Etna (Sicily) earth walls have been built to divert lava away from a cable car used by thousands of tourists every year.Education and planning – Locals educated in how to look for signs of a likely eruption e.g. Sicily, locals are taught to look for changes in the consistency of the lava.

EMS Geography GCSE Revision: Question(s) Answer(s)TECTONIC LANDSCAPES Case study: Chances Peak eruption, Montserrat

(1997)- Montserrat is a volcanic island on a destructive


Explain the causes of a volcanic eruption you have studied. Exam tip: You must know a range of place-specific points

plate

boundary.- The two plates that meet at this plate boundary are the North American plate which is subducted under the Caribbean plate.

- Produced a huge ash cloud which covered the southern part of the island. Pyroclastic flows of hot rock and ash were also thrown out of the volcano.


Explain the effects of a volcanic eruption you have studied on people and the environment. Exam tip: You must know a range of place-specific points

Case study: Chances Peak eruption, Montserrat (1997)

Effects on People:- 19 people killed by the pyroclastic flows.- Villages of Farm and Trant were completely buried by ash flow.- 150 homes destroyed.- Transport routes destroyed: Bramble airport was closed which disrupted international aid which was coming to help the islanders.

Effects on the environment:- 4km2 covered by ash and rock.- Pyroclastic flows caused the river Belham to flood.- Pyroclastic flows removed all vegetation in the south of the island including the ridges around Farrell’s Yard.

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WordPress.com · Web view- As the plate move apart, pressure causes the crustal rocks to fracture and a gap and ridge (mid-oceanic ridge) form – e.g. Mid-Atlantic ridge - Magma