This set of revision cards is on earthquake, something that might possibly come up in the SDME in 2014.

  • Created by: SMBStoker
  • Created on: 06-04-14 19:16

Basic Information

  • Earthquakes occur in narrow bands which match the outlines of the earth's tectonic plates.
  • They are caused by a sudden movement in the earth's crust.
  • Most take place at plate boundaries.
  • The place underground where an earthquake originates is called the focus.
  • The point onthe surface directly above the focus is called the epicentre.
  • A fault line is where a section of crust splits or cracks during an earthquake.
  • Seismic waves are waves of energy that travel out from the focus during an earthquake.
  • Earthquakes happen when two or more tectonic plates lock together due to friction.
  • The forces moving the plates continue to apply pressure on the plates.
  • This builds up until eventually the plates move without warning and the crust might split open.
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Richter Scale and Mercalli Scale

  • The Richter scale runs from 1 to 10 and measures the amont of energy released by an earthquake.
  • The Mercalli scale runs from 0 to 12 and measures the amount of damage done by an earthquake.
  • The Richter scale is logarithmic, each number being 10 times more powerful than the previous number.
  • So an earthquake measuring 7 is 1 times more powerful than one measuring 6.
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Primary Effects

Primary Effects are the immediate effects of an earthquake. They include:

  • Buildings collapsing.
  • Liquefaction, where shaking causes water in the soil layers to be brought to the surface and buildings to subside.
  • Objects falling from buildings and other structures, e.g. signs, glass and cables.
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Secondary Effects

Secondary effects are the after-effects of an earthquake. They include:

  • Fire and landslides.
  • Tsunamis, such as the December 2004 tsunami that killed almost 300,000 people.
  • Disease from unclean water supplies and lack of hygiene, such as typhoid and cholera.
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Short Term Responses

  • Emergency aid such as food, water, shelter and medical care.
  • Specialist rescue teams with lifting machinery, sniffer dogs and heat-sensing equipment.

Long Term Responses

  • Development aid to assist with the rebuilding and reconstruction of the affected area.
  • Money to help businesses re-start
  • Planning from local and national authorities to prepare for future earthquakes.
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Preparing for Earthquakes

People can prepare for earthquakes in a number of ways:

  • Predict where they might happen.
    • Geologists use seismometers to measure tremors that could indicate afuture earthquake.
  • Prepare for when an earthquake happens.
    • Earthquake-prone countries run earthquake drills each year and peoplehave earthquake kits containing essential items for survival.
  • Prevent damage during an earthquake.
    • Strict building regulations stop unstable buildings from being constructed.
    • New buildings in earthquake-prone countries have to be designed to be earthquake-proof.
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Case Study - LEDC

  • Earthquake that hit Haiti in January 2010 was 7 on the richter scale.
  • Over 200,000 people were killed and over 300,000 people injured.
  • Worst hit was the capital city, Port-au-Prince.
  • A third of the buildings collapsed, making 1.5 million people homeless.
  • The earthquake destroyed the country's port, airport, parliament, presidential palace and police headquarters.
  • This made it hard for emergency help to get to Haiti.
  • A poor country, Haiti did not have the resources to be well-prepared for an earthquake.
  • It lacked the skilled people or equipment to respond effectively afterwards.
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Case Study - MEDC

  • An earthquake measuring 7.2 on the Richter scale hit Kobe, Japan, in January 1995.
  • Out of 1.5 million, 5000 people died and 300,000 were made homeless.
  • It caused over £100 billion of damage.
  • 7500 houses collapsed and fires spread rapidly as gas pipes broke.
  • Water mains fractured, making it hard to put out fires.
  • An elevated road collapsed, as did sections of the bullet train track.
  • A rich country, Japan has more than 1000 tremors every year, so people are used to earthquakes and know what to do.
  • There are strict building controls and well-trained and equpped emergency response teams.
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