Tectonic Plates

How an earthqauke occurs?

Richter scale

Impacts of an earthquake- short term  

Impacts of an earthquake- long term 

Factors affecting the impact of an earthquake

Effects of an Earthquake or Volcano in an LEDC 

Kobe earthquake- Case Study: Basics, primary and secondary effects, Short and long term responses

Plate boundary types 

Types of volcanoes 

Effects of volcanic eruptions 

Positive and negative effects of a volcanic eruption 

Mount St. Helens MEDC- Casestudy:  Basics, Primary and secondary effects of eruption, Stort term and long term responses

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  • Created by: GARGI
  • Created on: 10-05-12 12:56

How an earthqauke occurs?

•Tectonic plates are locked together by friction

•Pressure builds up due to movement in the mantle (convection currents)

•Rock breaks along a weak point (fault lines)

•Pressure has built up to such an extent that tectonic plates suddenly move

•The stored energy is released in seismic waves

•The earth’s surface shakes; i.e. EARTHQUAKE

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Happens in areas where there is tectonic activity (normally on tectonic plate boundaries)

Place beneath the surface where the pressure is released is called the FOCUS of the earthquake

The EPICENTRE of a quake is on the surface directly above the focus

Seismic waves are caused and spread out from the focus, getting weaker the further from the focus they are

Quakes with a focus near the surface are normally more devastating

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Richter scale

Power of a quake is measured using a Seismometer; detects vibration caused by a quake. Plots vibration on a seismograph Strength, or magnitude, of quake is measured using the Richter Scale; numbered 0-10 Quakes that measure one/two are common and can happen everyday in some places (San Francisco). So small people don’t feel them, only picked up by a seismometer Quakes measuring seven/eight can be devastating. Quake in China’s south-western Sichuan province (May 2008) measured 7.8 on the scale. These quakes can cause major loss of life and cost million, even billions of dollars in damage

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Impacts of an Earthquake: Short term


  • People may be killed or injured 
  • Homes destroyed or damaged 
  • Transport disrupted 
  • Water and gas pipes might break; cause contamination of water or gas- fuelled fires


  • Shops and businesses destroyed 
  • Looting may occur which leads into insurance claims 
  • Damage to transport makes trading difficult,as well as access for emergency services
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Impacts of an Earthquake: Short term continued...


  • Fires spread, destroy wooded areas or buildings (gas-fuelled fires)
  • Current landscape destroyed, damaged or changed
  • Landslides may occur, cause transport problems
  • Tsunami’s might cause flooding in coastal regions
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Thanks.. somewhat helpful ..:D

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