Earthquakes

KS3_geography_title_borderplatetectonics

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EarthquakesPlate Tectonics

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Contents

Earthquake basics

Limiting the damage

Comparing earthquake impact

A case study: The Indian Ocean earthquake

Summary activities

The key concepts covered are:

Place, Space and Physical and human processes.

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Earthquake basics

Earthquake basics

Be able to describe whereearthquakes occur.

Understand the termsfocus and epicentre.

Be able to suggest waysto measure earthquakes.

By the end of this section, you will:

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Where do earthquakes occur?

PacificPlate

NorthAmericanPlate

AfricanPlate

Indo-AustralianPlate

EurasianPlate

SouthAmericanPlate

NazcaPlate

Do the location of earthquakes form a pattern?

Earthquakes are vibrations of the earth’s crust caused bymovement at plate boundaries and major fault lines. The redareas on the map are where earthquakes are most common.

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Earthquakes can occur at all four major plate boundaries butthe most severe earthquakes usually occur at conservativeand destructive plate boundaries.

Conservative boundary

Destructive boundary

What are earthquakes?

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Destructive plate boundary

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Conservative plate boundary

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Epicentre and focus

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The Richter scale can beused to measure themagnitude (power) of atremor using an instrumentcalled a seismograph.

How are earthquakes measured?

It is a logarithmic scalewhich means that a size ‘6’earthquake on the Richterscale is 10 times largerthan a size ‘5’ and 100times larger than a size ‘4’.

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How does a seismograph work?

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The Mercalli scale rates an earthquake's magnitude based onobservations of the damage it causes on a scale of 1 to 12.

The Mercalli Scale

Items shake fromshelves: scale 5

Buildings collapse:scale 10

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Limiting the damage

Limiting the damage

Be able to identify thelong and short termimpacts of earthquakes.

Be able to suggest waysthat the impacts ofearthquakes can bereduced by humans.

By the end of this section, you will:

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What effects do earthquakes have?

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Protect

construct buildings and roads that withstand shaking.

Plan

emergency services can practise for disaster

stock-pile medicine, food, blankets etc

educate the population in what to do during and after.

How can we limit earthquake damage?

water levels can change in wells and lakes

foreshocks can be detected by a seismometer and atilt meter can detect movement within rock

animals can act strangely before an earthquake.

Predict

Predicting earthquakes accurately enough to evacuatepeople is nearly impossible but:

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Planning and protecting

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Which shape ofbuilding would be most‘earthquake proof’?

Buildings in earthquake zones

strong lintels

overlapping bricks

deep foundations

What makes a building strong?

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This is San Franciscoin the USA.

This skyscraper has beendesigned and constructedto be ‘earthquake-proof’.Its wide base lowers thestructure’s centre of gravityand makes it more stable.

Building in earthquake zones

San Francisco is near theSan Andreas Fault andtherefore the cityexperiences earthquakes.

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Before and after responses

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Comparing and contrastingearthquakes

Comparing and contrastingearthquakes

Have compared theimpacts of earthquakes ona MEDC and a LEDC.

Have considereddevelopment as a key issuein earthquake response.

By the end of this section, you will:

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magnitude of the earthquake

physical landscape

time of day

building design and construction

emergency service response

GDP

education.

Which factors do you think are the most important?

Which factors are related to the wealth of the country?

How can education limit earthquake damage?

What factors affect earthquake damage?

Different factors affect the damage an earthquake causes:

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Why might morepeople have died inPakistan than in LA?

How different were theimmediate effects ofthese earthquakes?

How different were theimmediate effects ofthese earthquakes?

What the papers say

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Pakistan lies on a collisionboundary between the Indianplate and the Eurasian plate.

The Indian plate is movinginto the Eurasian plate at arate of 67 mm per year.The motion causes theHimalayas to rise, as wellas producing earthquakes.

Epicentre of the 2005Pakistan earthquake.

What’s moving in Pakistan?

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What’s moving in California?

The San Andreas fault is aconservative fault that runsalong the West of California.

Los Angeles lies very close to it.

All land west of the fault on thePacific Plate is moving to theNorth-west. All land east of thefault on the North American plateis moving to the South-west.

The epicentre of the1994 LA earthquake

The rate of slippage acrossCalifornia is 33-37 mm per year.

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Comparing devastation

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Using these photos as a guide, can youtell a story of the effects the earthquakehad and how people responded to it?

Using these photos as a guide, can youtell a story of the effects the earthquakehad and how people responded to it?

Devastation and recovery in Pakistan

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Earthquake aid

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Case study: the IndianOcean earthquake

A case study:

The Indian Ocean earthquake

Understand what atsunami is.

Understand how anearthquake in the IndianOcean caused a tsunamiand be able to state someof its impacts.

By the end of this section, you will:

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Tsunamis are tidal waves caused by underwater earthquakes.A tsunami travels at speeds between 400 and 600 mph.

The tsunami spread across the Indian Ocean affecting coastalareas of 14 countries including Indonesia, Sri Lanka, India,Bangladesh, Myanmar, The Maldives and Malaysia.

The tsunami in the Indian Oceanoccurred on 26th December2004. The earthquake measured9.0 on the Richter Scale andoccurred off the northern tip ofSumatra. Over 226,000 peopleare presumed to have died inthe disaster.