1. Seismic Events Causes of Earthquakes Distribution of Earthquakes
Measuring Earthquakes
The Effects of Earthquakes

2. WHAT IS AN EARTHQUAKE? Sudden release of energy
Creates seismic waves (similar to waves through water)
Waves spread out spherically
Greatest damage occurs at the epicentre

3. P & S waves Two types of wave explained.
Circle of power demonstration.
P & S travel through the interior of the earth – out from the epicentre.

4. P-waves P waves (primary waves) are compressional waves.
In solids, these waves generally travel almost twice as fast as S waves.
P waves can travel through any type of material.
In air, these pressure waves take the form of sound waves.
They travel at are 330 m/s in air, 1450 m/s in water and about 5000 m/s in granite. (m/s = meters per second.)

5. PRIMARY WAVE ‘p-wave’ Longitudinal Sudden jolt felt as the quake hits.5 5

6. S waves
S waves (secondary waves) are transverse which means that the ground is displaced perpendicularly (sideways) to the direction of movement.
The ground moves alternately to one side and then the other. (or up or down… depending on the direction of the wave.)
S waves can travel only through solids, as fluids (liquids and gases)
Their speed is about 60% of that of P waves in a given material.
S waves arrive second in a seismic station because of their slower speed.
They are sometimes called shear waves.

7. SECONDARY WAVE ‘s-wave’
Transverse (shake at right angles to the direction of the wave.)
Sustained shaking felt as quake hits 7 7

8. L wave
The particle motion of a Love wave forms a horizontal line perpendicular to the direction of movement (i.e. are transverse waves).
Since Love waves travel on the Earth's surface, the strength (or amplitude) of the waves decrease exponentially with the depth of an earthquake.
Surface waves therefore decay more slowly with distance than do body waves, which travel in three dimensions.
Large earthquakes may generate Love waves that travel around the Earth several times before dissipating.
Since they decay so slowly, Love waves are the most destructive outside the immediate area of the focus or epicentre of an earthquake. They are what most people feel directly during an earthquake.

9. LOVE WAVE. L-wave

10. Read the book pages 24 - 27 Worksheet– Sheet 5 & 6
Lets get an overview.
Read the book pages
Worksheet– Sheet 5 & 6

11. Distribution of Earthquakes
What is the distribution of Earthquakes?
Read the section in the book then use following statements to make a short paragraph explaining the distribution of Earthquakes.
The Pacific Ring of Fire
70% of Earthquake and Volcanic activity is found around it’s edges
Volcanoes and Earthquakes are frequent.
Represents the destructive plate boundaries around the edges of the plate. 11

12. THE RICHTER SCALE Invented by Charles Francis Richter in 1935
Measure of an earthquake’s magnitude
Scale between 0 and 10(theoretically)
Logarithmic scale

13. How does a seismograph work?
Measurement – using a seismograph
Magnitude: A measure of the size of an earthquake.
Frequency: Is the number of occurrences of a repeating event per unit time.

14. Worksheet 1.10

15. Effects of an Earthquake
National Geographic 4 min clip – the effects of earthquakes. Link
The text book explains several effects
Liqufaction
Landslides/avalanches
Effects on built environment
Tsunamis

16. Liquefaction Explained

17. What happened in San Francisco?
Year 9 Worksheet 17

18. Aftershocks
A tremor (or one of a series of tremors) occurring after the main shock of an earthquake : Video

19. Mass Movement when masses of rock, earth, or debris move down a slope.
Mass movement is movement of masses of bodies of soil, bed rock, rock debris, soil, or mud.
They may be very small or very large, and can move at slow to very high speeds.
Usually occur along steep-sided hills and mountains because of the pull of gravity.
An avalanche is a sudden flow of a large mass of snow or ice down a slope, sometimes at speeds exceeding 160 km/hr.
Mass movement and avalanches can be started when earthquakes destabilise rock and start a slide.

20. Tsunami - What is a Tsunami?
Tsunami -a large wave, or series of waves, caused when an earthquake causes massive undersea crust movements and/or collapses which displace the water above.
Earthquakes deform the ocean floor, pushing the overlying water up into a tsunami wave.

22. Video of Boxing Day Tsunami
Tsunami – Caught on Camera
Scale showing the size of the tsunami waves that hit Indonesia.

23. Case study – Boxing Day Tsunami.
Make a 5 point PowerPoint to get the key facts about the Tsunami across. Use case study on page 29 to help.
Why it occurred.
Where it started.
What it effected.
Positive side effects.

24. Plenary 24

25. Earthquakes don’t kill people, buildings do.25

26. Earthquakes don’t kill people… BUILDINGS DO!!!
Starter
Earthquakes don’t kill people… BUILDINGS DO!!!

27. Port-au-Prince, Haiti 27 27

28. BUILDINGS Side to side forces that cause collapse
Damage caused by lateral forces 28 28

29. Building tilted due to first story building collapse29 29

30. HOW TO BUILD SMALL BUILDINGS
Shear walls
Concentrate the damage
Cross Bracing
Reinforced stone wall 30 30

31. Construction of Pearl River Tower, China
Cross bracing
Construction of Pearl River Tower, China 31 31

32. LARGER BUILDINGS Base isolation
Left: regular building Right: base isolated building 32 32

33. Ways of improving resistance to earthquakes33 33

34. SKY SCRAPERS Tuned Mass Damper
The tuned mass damper at the top of the Taipei 101 34 34

35. HAITI
A poor neighbourhood, Port-au-Prince 35 35

36. CHILE
Damaged building, Concepcion 36 36