The Restless Earth

Unit 1: section B In the physical paper you will have to answer 3 questions; 1 on water on the land, 1 on the restless earth and 1 on the coastal

zone. The paper is 1:30hrs long therefore you should aim to spend 30 minutes on each question.

The Syllabus

Opposite is a copy of the syllabus for this unit of work.

It should help you to highlight any gaps in your notes and learning.

Main Case Studies

MEDCs - Seattle, USA, 2001 or California, USA, 2003, or

Kobe, Japan, 1995 andLEDCs - Gujarat, India, 2001

or Bam, Iran, 2003 or Sichuan, China, 2008

A case study of an earthquake in a rich part ofthe world and one from a

poorer area – their

specific causes; primary and secondary effects;

immediate and long term responses – the need

to predict, protect and prepare. Contrasts in

effects and responses will be clear.

The AlpsA case study of one range of fold mountains.The ways in which they are used – farming, Hydro Electric Power, mining, tourism and

how people adapt to limited communications, steep relief, poor soils.

Soufrière Hills Volcano, Montserrat

A case study of a volcanic eruption – its cause; primary and secondary effects;

positive and negative impacts; immediate and long term responses

Asian Tsunami, 2004A case study of a tsunami – its cause,

effects and responses.

You may also want to use elements from the Japan 2011 Tsunami as

well although the long term responses have yet to be known

The case studies you use will depend upon your

teacher. Miss Bendon’s class should focus on Bam and California; Mr Mann’s class should focus on Kobe

and Sichuan; and Mrs Frost’s class should focus on

Bam and Kobe.

Key idea no.1

The Earth’s crust is unstable, especially at plate margins.

You must know:•Distribution of plates; contrasts between continental and oceanic crust.•Destructive, constructive and conservative plate margins.

The structure of the Earth

The Earth’s crust is not a continuous layer, but is split up into seven large

tectonic plates and many smaller ones.

2 types of plates…• Oceanic plates – the crust is thin (5-15km), but

dense (heavy) as it is made of basaltic (igneous rock formed from quick cooling lava/magma) rock.

• Continental plates – the crust is much thicker (up to 100 km), but lighter as it is made of granitic (igneous rock formed from slow cooling magma/lava) rocks.

Plate margins• When plates move in

opposite directions e.g. the North American and Eurasian plates.

• Usually occurs under the oceans (e.g. the Mid-Atlantic Ridge).

• A the plates move apart the gap is filled with rising magma from the mantle, which create shield volcanoes – which in turn can become volcanic islands such as Iceland.

Constructive plate margins

Plate margins• When plates move in

together e.g. the Nazca and South American plates.

• Occurs when the denser oceanic crust is subducted under the lighter continental crust (at a subduction zone, an oceanic trench)

• In the subduction zone, energy builds and is sometimes released as an earthquake. Composite volcanoes an be formed when magma rises causing a volcanic eruption.

• Fold mountains may occur along these boundaries (e.g. The Andes along the west coast of south America.

Destructive plate margins

Plate margins• When plates slide

past each other e.g. the Pacific and North American plates along the San Andreas Fault.

• Pressure builds from the friction and may cause a ‘jerk’ which causes an earthquake.

Conservative plate margins

Key ideas no. 2 & 3• Unique landforms occur at plate margins.and• People use these landforms as a resourceand adapt to the conditions within them.

You must know:• Location and formation of fold mountains,

ocean trenches, composite volcanoes and shield volcanoes.

• A case study of one range of fold mountains.

Formation of landforms on plate boundaries

1. Fold Mountains

2. Ocean Trenches

3. Shield Volcanoes

4. Composite Volcanoes

The majority of Ocean Trenches are located around

the edges of the Pacific Ocean. They are associated

with destructive plate boundaries. At these

margins, the subduction zone is the ocean trench.

These trenches are inaccessible to humans and so have no human use. It is the continental shelf where the greatest human activity occurs – mainly fishing and

drilling for oil and gas.

Shield Volcanoes

Plate Margin Constructive

Formation As the plates move apart, magma rises upwards from the mantle to fill the gap. This adds new rock to the spreading plates. Some of the magma may also be forced out to the surface through a vent. Some volcanoes grow high enough to form volcanic islands.

Form of volcano Shield volcano (made from BASIC lava – low silica content – very runny and travels long distances).

Characteristics It has a wide base and gentle slopes.Made of lava only.Regular and frequent eruptions.Lava pours out with little violence.

Examples Hekla and Surtsey in Iceland.Mauna Loa and Kilauea in Hawaii.

Composite Volcano

Can you draw a diagram of a composite volcano and label it to show its main features?

Plate Margin Destructive

Formation When the plates collide, the denser oceanic plate is pushed down into the mantle. Here the plate melts and is destroyed in the subduction zone. In the subduction zone the plate forms a pool of magma. The great heat and pressure may force the magma along a crack where it erupts at the surface to build a volcano.

Form of volcano Composite cone volcano (made from ACID lava – high silica content – very viscous and travels short distances before it cools).

Characteristics Tall cone with a narrow base and steep sides.Made of alternate layers of lava and ash.Irregular with long dormant periods.Violent explosions possible.

Examples Etna, Vesuvius and Stromboli in Italy.Krakatoa in Indonesia.

Exam Question

The examiner says… when stating differences, make sure that you mention both – not just one of the them.

Differences could be any two relating to – • Lava• Eruption• Shape• Composition• Plate boundary

State two differences between composite and shield volcanoes (2 marks)

A case study of one range of fold mountains

• Name: The Alps• Location: Europe (Italy, France, Switzerland,

Austria and Slovenia).• Highest peak: Mont Blanc (4810 m)• Formed:35 million years ago• Created by: The African plate pushing north

against the Eurasian plate.• Made up of: sediments deposited in the

geosyncline of the Tethys Sea

Human activities include:

•Transhumance Farming and

forestry

•Tourism

•Hydro-electric power (H

EP)

and industry.

YOU MUST BE ABLE TO DESCRIBE

THESE HUMAN ACTIVITIES AND

EXPLAIN WHY THEY TAKE PLACE

HERE. CONSIDER ALSO THE

CONFLICTS THESE ACTIVITES MAY

CREATE.

Key idea no. 4

Volcanoes are hazards resulting from tectonic activity. Their primary and secondary effects are positive as well as negative. Responses change in the aftermath of an eruption.You must know:•Characteristics of different types of volcanoes.•A case study of a volcanic eruption – its cause;primary and secondary effects; positive andnegative impacts; immediate and long termresponses. •Monitoring and predicting volcanic eruptions.

Characteristics of different types of volcanoes

Characteristics It has a wide base and gentle slopes.Made of lava only.Regular and frequent eruptions.Lava pours out with little violence.

Characteristics Tall cone with a narrow base and steep sides.Made of alternate layers of lava and ash.Irregular with long dormant periods.Violent explosions possible.

Shield Volcano

Composite Volcano

Case study: Soufrière Hills Volcano, Montserrat

• Cause (plate boundary)• Primary effects (people injured and killed; buildings, property

and farmland destroyed; communications and public services disrupted)

• Secondary effects (shortages of drinking water, food and shelter; spread of disease from contaminated water; economic problems (cost of rebuilding and loss of economic activities); social problems (family losses and stress).

• Immediate and long term response (evacuations; monetary aid; rebuilding etc). This is the case study in UGG which you would have

done with your teacher. You also did a different case study when Miss Humphrey’s came in. As long as you can apply each of these points to a case study it will be fine to use in the exam.

Monitoring and predicting volcanoesPredicting and preparing for volcanic eruptions can help reduce the

damage that they cause. Poorer countries cannot afford to monitor volcanoes properly and may have less effective emergency

plans.•When magma is on the move it causes small earthquakes and these can be measured by seismometers.•In the days before an eruption, the hot magma moves towards the surface which causes ground temperatures to rise – this can be picked up by heat seeking cameras on satellites.•Tiltmeters measure volcanoes moving (caused by the rising magma). GPS also detects movement.•Immediately before an eruption the volcano will expel an increased amount of gas and steam.

Key idea no. 5

Super-volcanoes are on a much bigger scale than other volcanoes and an eruption would have global consequences.

You must know:

•The characteristics of a super-volcano and the likely effects of an eruption.

The term "super-volcano" implies an eruption of magnitude 8 on the Volcano Explosivity Index (VEI) , meaning that more than 1,000 cubic kilometres (240 cubic miles) of magma (partially molten rock) are erupted. They usually occur under hot spots or at subduction zones.

Global locations

• Toba, Indonesia; • Taupo, New Zealand; North Island• Long Valley, California, USA; • Longridge, Oregon, USA; • Yellowstone National Park, Wyoming

Yellowstone, Wyoming, USA

• Previous eruptions – • 640,000 years• 1.3 millions years• 2.1 million years ago (the biggest eruption)

An eruption is (over)due!

The effects of ash from Yellowstone

• Likely to cover ¾ of the USA• 90% of the people killed within 1000km• Most deaths by inhaled ash turning to cement• East coast of USA could have 1 cm depth of ash• Reduces sunlight + triggers rainfall• Communication links disrupted• 30cm can crush a roof• Kill crops + contaminate water supplies

The last super-volcano to erupt was Toba (Indonesia) 74,000 years ago

• The last super-eruption plunged the world into a freezing, volcanic winter that lasted a decade, and threatened the human population with extinction.

• While ordinary volcanoes can kill thousands of people and destroy entire cities, it's thought a super-volcano could claim up to a billion lives and devastate continents.

Key idea no. 6

Earthquakes occur at constructive, destructive and conservative plate margins.

You must know:•Location and cause of earthquakes.•Features of earthquakes – epicentre, focus, shock waves and the measurement of earthquakes using the Richter and Mercalli Scales.

Location of earthquakes

Earthquakes occur at constructive, destructive and conservative plate boundaries

The cause of earthquakes

• Over 90% of earthquakes occur where plates are colliding at destructive plate boundaries. The pressure and energy which builds in the subduction zone as one plate is subducted under another is released in an earthquake.

• The point at which the earthquake happens below the surface is called the focus.

• The point on the surface directly above the focus is called the epicentre. This is where the greatest force of the earthquake is felt.

Exam question

1 (a) (ii) Draw a labelled diagram(s) to explain why earthquakes occur at conservative plate boundaries. (4 marks)

What is the examiner looking for?

1 (a) (ii) Diagram should show plates moving in similar directions (but not the same); should label to show sliding past each other; or same direction, but at different speeds; the pressure building up as the plates stick and the sudden release causing the jerking movement which is the earthquake.An example may be used – likely to be San Andreas Fault. Diagrams may be plan view, cross section or a combination of both.

Key idea no. 7

The effects of earthquakes and responses to them differ due to contrasts in levels of wealth.

You must know:•A case study of an earthquake in a rich part of the world and one from a poorer area – their specific causes; primary and secondary effects; immediate and long term responses – the need to predict, protect and prepare. Contrasts in effects and responses will be clear.

The factors that control the effects of an earthquake

•High magnitude on Richter scale

•Shallow focus (near the surface)

•Sands and clays vibrate more (e.g. Mexico City)

•High density of population

•Residential area of a city

•Self-built housing

•Lack of emergency procedures (e.g. Gujarat in India)

•Low magnitude (below 5)

•Focus deep underground

•Hard rock surface (e.g. Seattle)

•Low density of population

•Urban area with open spaces

•Earthquake-proof buildings

•Regular earthquake drills

Great (or total) damageHigh number of deaths and injuries

Mercalli Scale VII-XII

Superficial damage to buildingsFew casualties

Mercalli Scale I-VI

Physical Physical

Human Human

Effects of an earthquake

Primary effects Secondary effectsCollapsing buildings, roads and bridges.People being killed by being trapped in their homes, places of work and cars.

THESE ARE DETERMINED BY A MIXTURE OF THE PHYSICAL AND HUMAN FACTORS

OUTLINED ON THE PREVIOUS SLIDE. THE CHANCE ELEMENT IS THE TIME OF DAY.

These are the after effects, such as fires, tsunamis, landslides and disease.•Fires are caused by earthquakes fracturing gas pipes & bringing down electricity wires. Firs spread quickly in areas of poor quality housing.•Tsunamis are giant sea waves caused by an earthquake on the sea floor & are really dangerous for people living along low lying coasts.•Landslides are most likely on steep slopes & in areas of weak rocks such as sands and clays.•Diseases such as typhoid & cholera spread easily when burst pipes lead to shortages of fresh water & to contamination from sewage.

Responses to earthquakes• Immediate emergency aid is needed everywhere where a

strong earthquake strikes.• Specialist rescue teams with sniffer dogs & lifting equipment,

and medical teams with field hospitals can be expected to be airlifted within hours to rich countries, thanks to advance preparations.

• The poorer the country the greater its reliance upon short-term aid from overseas.

• In the medium term, the need is for a quick return to normal life (or as near normal as possible) by repairing and replacing what has been lost & restarting economic activity. The focus needs to be switched from disaster aid to development aid.

Predict, prepare, protect

The ‘3 Ps’ are used to try and reduce the effects of earthquakes.

Predict

•Seismometers measure small fore-shocks that occur before the main earthquake. They also show increases in temperature, pressure and release of radon gas.

•Mapping previous earthquakes and looking for gaps where earthquakes are likely.

•Plotting regularity helps to show if there is a recognisable time-length pattern.

•Unusual animal and fish behaviour can indicate an earthquake is imminent.

Prepare

•Preparing disaster plans & carrying out regular practices. (In Japan Earthquake preparation is part of the curriculum).

•Training emergency services such as police, fire and ambulance crews.

•Organising emergency food, water, medical & power supplies.

•Setting up an efficient earthquake warning and information system using TV & radio.

•Strict building regulations.

Protect

•Building regulations should ensure that buildings are earthquake resistant and provide protection rather than causing danger in an earthquake. They should also restrict building on unstable surfaces like clay & reclaimed land where earth movement is greatest & building collapse is most likely.

•Earthquake resistant buildings are built with:

•Foundations sunk into bedrock;

•Rubber shock absorbers;

•Fore resistant building materials;

•Steel frames which ‘sway’.

A case study of an earthquake in a rich part of the world and one from a poorer

areaMEDCs - Seattle, USA, 2001 or California, USA, 2003, or

Kobe, Japan, 1995 or L’Aquila 2007 and

LEDCs - Gujarat, India, 2001 or Bam, Iran, 2003 or Sichuan, China, 2008

– their

specific causes; primary and secondary effects;

immediate and long term responses – the need

to predict, protect and prepare. Contrasts in

effects and responses will be clear.

The case studies you use will depend upon your

teacher. Miss Bendon’s class should focus on Bam and California; Mr Mann’s class should focus on Kobe

and Sichuan; and Mrs Frost’s class should focus

on Bam and Kobe.

Key idea no. 8

Tsunamis are a specific secondary effect and can have devastating effects in coastal areas.

You must know:

•A case study of a tsunami – its cause, effects and responses.

Can you draw a diagram showing the cause and process of a tsunami?

Case Study: Asian Tsunami 2004

You may also want to use elements from the Japan 2011 Tsunami as well although the

long term responses have yet to be known

The USGS (United States Geological Survey) record of the earthquake

The waves spread out on their voyage of destruction

Within half an hour the waves had reached Sumatra and Malaysia

and swept ashore in Thailand.

Two hours later they reached Sri Lanka and India.

Within four hours they had crossed the ocean to the east coast of Africa

The killer wave strikes Kalutara Sri Lanka

The Asian Tsunami Yr 9

What…

Who…

When…

Why…

What next…

…was the magnitude / strength of the Earthquake on the Richter Scale?…occurred as a result of the Earthquake?…is a Tsunami?…region and countries were affected?

…did it affect most (which types of people)?…was killed in the Tsunami (how many people) and who was affected?…gave aid to the affected areas? (What kind of aid and how much)…(what feelings, emotions and losses did these people experience)

…did it occur? (date, time)…did the Tsunami hit different coastlines?

…did the Earthquake occur? (Which tectonic plates were involved and what type were they?)…did the earthquake cause a Tsunami?…was the Tsunami so devastating in the areas that it hit?

…what aid is needed to help people recover in the long term?…how will the tourist industry recover?…can these people’s lives ever return to how they were before the Tsunami? ?

You should confidently be able to

answer these questions.

Past paper questions• Explain why volcanoes are found at

destructive plate boundaries. (3 marks)• Describe the ways in which a super-volcano

is different from a volcano. (4 marks)

• Study the table which shows information about frequency and magnitude of earthquakes between 2000 and 2007.Describe the relationship between the magnitude of earthquakes and their frequency. (4 marks)

• Describe a method, other than the Richter Scale, of measuring earthquakes. (4 marks)

This answer is worth 4 marks -the examiner would be looking for the following…

Using case studies of earthquakes in rich and poor parts of the world, compare and

describe the immediate responses. (8 marks)

What does the examiner say?

Actual content will depend on the case study being used.

Immediate – Rich parts – response will be rapid; often practice emergencydrills; these will be put into effect / Emergency services mobilised,including helicopters, emergency departments of hospitals, fire service etc.Contingency plans for ensuring supplies of clean water, medical supplies,blankets, shelters.Poorer areas - There will be reference to the need to rescue people – maybe done by relatives and basic equipment or just by hand initially, a needto put out fires, to provide medical help, to ensure there is clean water (andfood). All of this may require international aid and teams of sniffer dogs,heavy equipment, medical staff, provision of water purifying tablets,blankets, setting up shelters, tents etc.

What should a level 3 style answer include?