EARTHQUAKES

Definition

Location Using resource 1 describe the global distribution of earthquakes.

Causes of an Earthquake at a conservative plate boundary.

The built up tension is now released and so is waves of energy.

Enormous tension builds up. Two plates begin to try and move.

The waves of energy called seismic waves travel in all directions

The tension causes the stuck rock to give way; this point is called the focus

The plates try to slide past each other.

As the rocks slowly settle in their new positions, aftershocks occur.

Suddenly one plate is now able to lurch forward.

As they try and move parts get locked.

Conservative plate boundary

Key Words: Foreshocks Focus Epicentre Seismic waves Richter scale Aftershocks

A series of small tremors in the days after the main quake.

Used to measure the magnitude (amount of energy released ) of a quake

A series of small tremors in the days before the main quake.

The point underground where a quake occurs.

Fast waves of energy released by a quake that travel through the rock to the surface

The location on the surface directly above the focus.

Social

Economic

Environmenta

l

Place the numbers 1-13 on the Venn diagram to classify the impacts into social, economic and environmental impacts

An earthquake has occurred in this area. Explain which area (the town or the forest) will receive the stronger earthquake?

Explain which area will receive more damage from the earthquake

Effects of Earthquakes

Buildings and bridges are reduced to rubble by the shaking ground.

Broken gas pipes lead to fires which destroy buildings

Aftershocks threaten to destroy weakened buildings

People are killed by earthquakes

Infrastructure for roads, trains and trams are damaged

Earthquakes trigger landslides and tsunamis, these destroy more buildings and cause more injuries and deaths

People are left homeless

• Underground water and sewage pipes are broken.

• Telephone poles and cables are destroyed.

• Shortage of clean water and lack of proper sanitation which can lead to outbreak of disease like cholera.

• Blocked or destroyed roads make it difficult for emergency services to get through.

• Businesses are damaged or destroyed causing unemployment.

• People may suffer psychological problems if they knew people who died or if they lose their home

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8

2

4

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12

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Key Points

Earthquake in Haiti 2010 Earthquake in Japan 2011

To what extent are earthquakes more severe in LEDCs?

San Francisco has suffered badly at the hands of earthquakes. The government has decided to invest further in earthquake prevention methods. They have three options.The three options are:

1. Invest in prediction techniques, such as a seismograph to accurately predict earthquakes.

2. Invest in preparation . This would include training emergency services and creating planned evacuation routes.

3. Invest in protection . This would involve investing in earthquake proof buildings.

4.1. State your chosen option.

2. Explain the advantages of your chosen option.

3. Explain any disadvantages of your option.

4. Explain any advantages and disadvantages of an option you rejected.

Management Strategies Advantages Disadavantages MEDC/LEDC/bothPrediction

It is impossible to predict when an earthquake will happen but it is possible to look for clues.

Hazard Mapping .Sensitive instruments measure earth movements and check the stress build up in rocks. Maps can be produced of the probability of earthquakes occurring. They can use instruments to give early warning of tsunamis.

Cost and reliability .If predictions are wrong there are social and economic consequences such as ……..

Foreshocks Several earthquakes can occur in a short space of time, so scientists can predict the chances of a major shock occurring

Recent earthquake plotting The number of recent earthquakes can be plotted to show if a major earthquake can be expected.

Animal behaviour

Planning New buildings Depends on technology to assess the areas that are most at risk

Firebreaks and flexible pipes

Cost

Emergency services Emergency services will train for this event to reduce loss of life and to implement disaster plan effectively. E.g. practice in rescuing people from collapsed building

Evacuation routes In LEDCs a percentage of the population may not have their own means of transport

Building Techniques/Action

Earthquake proof buildings Only useful with the construction of new buildings.

Education Emergency kit Those in LEDCs less likely to be prepared.

Earthquake Drills and evacuation

Aid Emergency aid –helps after the event but does not prevent an earthquake.. Aid can be slow if infrastructure is damaged.

5. Explain why your option is more sustainable than the other two.