1. 5th Year Geography Earthquakes
10/11/2018
Leaving Certificate Geography
Unit 1.4 : Earthquakes
Mr. McMahon
10/11/2018
Mr.C.McMahon
Mr.C.McMahon

2. Learning Outcomes You will learn….
What an earthquake is.
Why they occur.
How their global pattern is explained by the location of fault lines.
How earthquake zones are located and measured.
How they are predicted.
How earthquakes impact upon the landscape and human populations.
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Mr.C.McMahon

3. Earthquakes-The Past Ten Years
Place
Richter Scale
Casualties
2004
Sumatra Indian Ocean
9.1
230,000
2008
Sichuan Province China
7.9
87,587
2005
Pakistan
7.6
86,000
2010
Japan
6.8
12,690 (14,000 unaccounted for)
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Mr.C.McMahon

4. What is an Earthquake ? Damage Decreases From Epicentre Scarp
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Mr.C.McMahon

5. What Causes Earthquakes?
The plates of the crust are constantly moving.
Sometimes plates jam or stick together.
This creates a build up of energy when one or both plates slip releasing seismic waves that can violently shake the surface above.
10/11/2018
Mr.C.McMahon

6. Key Concepts
Focus: The point where an earthquake begins in earth’s crust. Earthquakes can be shallow or deep focus.
Epicentre: The point on the surface that is the worst affected by a quake. Damage lessens the further one moves from the epicentre.
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New Zealand Earthquake 2011
Mr.C.McMahon

7. The Global Distribution of Earthquakes
5th Year Geography Earthquakes
10/11/2018
The Global Distribution of Earthquakes
10/11/2018
Mr.C.McMahon
Mr.C.McMahon

8. Location of Earthquakes
Earthquakes do no occur randomly.
Their location is based on plate boundaries.
Earthquakes occur at convergent, divergent and transform boundaries.
10/11/2018
Mr.C.McMahon

9. Transform Fault. California USA. Rifting: East Africa
The Subduction zone of Japan is the most earthquake prone area in the world.
Transform Fault. California USA.
Rifting: East Africa
Divergent: Mid Atlantic Ridge.
Convergent: Columbia -Chile
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Mr.C.McMahon

10. Seismic waves
Primary (P) waves: Fast waves that compress then expand molten material
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Mr.C.McMahon

11. Secondary (S) waves are slow as they have to travel through solid rock.
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Mr.C.McMahon

12. Earthquake Waves
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Mr.C.McMahon

13. Surface Waves: The slowest waves that expend their energy on the surface causing anything on it to move up and down.
Principle. Energy from waves is absorbed by material as it travels through them. Thus the father a wave travels the more energy they expend.
10/11/2018
Mr.C.McMahon

14. Measuring Earthquakes
The Seismograph
Three are needed for a full set of data
Horizontal measuring waves North-South
Horizontal- East to West.
Vertical Movement
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Mr.C.McMahon

15. The Richter Scale Logarithmic Scale.
Each unit is 10 times the wave activity of the previous for example a force 8 is 10 times greater than a force 7.
The force is measured at a greater rate of 30.
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Mr.C.McMahon

16. Predicting Earthquakes
Earthquake zones are identified.
Predictions based on timeframes.
Seismologist Identify seismic gaps- points between plates where earthquakes are likely to begin.
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Mr.C.McMahon

17. Early Warning Systems
Early Warning systems based on modern communication systems are being developed.
Monitoring animal behaviour.
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18. 10/11/2018
Mr.C.McMahon

19. Destruction by Earthquakes
Destruction by earthquakes depends on the following.
The depth of the focus
The population density around the epicentre.
Economic development and the standard of buildings.
Overlying Topography
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Mr.C.McMahon

20. Soil Liquefaction
Liquefaction is the process of soil, clay and sand turning into a sludge.
During an earthquake ground water mixes with the soil types to produce a material like quicksand.
This undermines the foundations of bridges, roads, dams etc….
Consequences ?
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21. Other Dangers Falling Debris Flooding Burst gas and sewage mains.
Spread of disease
Disruption to emergency services
Tsunamis
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Mr.C.McMahon

22. Tsunami
Giant waves that are generated when an earthquake occurs on the sea floor.
See Indian ocean Earthquake- Tusnami animation Wikipedia
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Mr.C.McMahon

23. Limiting Earthquake Damage
Retro- fitting of Old Buildings.
The development of advanced warning systems
Tapered frames to increase a buildings frames integrity
The use of shock absorbers in a buildings columns and foundations.
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Mr.C.McMahon

24. Case Study: The Haiti Earthquake
5th Year Geography Earthquakes
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Case Study: The Haiti Earthquake
Tuesday 12th January 2010.
Measured 7.0 Richter Scale
Focus at 13 KM
Epicentre 13KM from the capital Port Au Prince
10/11/2018
Mr.C.McMahon
Mr.C.McMahon

25. Haitian Earthquake Map
5th Year Geography Earthquakes
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Haitian Earthquake Map
10/11/2018
Mr.C.McMahon
Mr.C.McMahon

26. Case Study: The Japan Earthquake
5th Year Geography Earthquakes
10/11/2018
Case Study: The Japan Earthquake
Struck on March 11th 2010
Richter Scale 9.0
Epicentre 60KM from the coast triggered Giant Tsunami
Over 12,690 dead and 14,000 unaccounted for.
10/11/2018
Mr.C.McMahon
Mr.C.McMahon

27. Japan Earthquake Map http://www.youtube.com/watch?v=hOe8PMoKdI8
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Mr.C.McMahon

28. Key Concepts Earthquake Focus Epicentre Seismology Seismograph
Richter scale
Magnitude
P Waves
Q Waves
S Waves
Earthquake Prediction
Early Warning Systems
Scarp
Tsunami
Tremor
Aftershocks
10/11/2018
Mr.C.McMahon