understanding faults and earthquakes

4. What is an earthquake?
• it is the shaking of the surface of the
Earth, resulting from the sudden
release of energy in the Earth's
lithosphere that creates seismic waves.

5. What causes earthquakes?
• It usually caused when rock (or the
solid part of the earth) underground
suddenly breaks along a fault.

10. Faults
• are fractures, or zone of weakness on the
earth’s crust where ground movement or
displacement has occurred or can happen

13. Three Types of Fault
Strike-Slip
Normal
Reverse

14. •when the hanging wall moves
downward in relation to the foot wall

15. • when the hanging wall moves upward
in relation to foot wall

17. Strike-slip

18. Normal

19. Normal

20. Reverse

21. Strike-slip

24. How Seismographs Work?
the pendulum remains
fixed as the ground
moves beneath it
A seismograph is an instrument used for recording
the intensity and duration of an earthquake.

25. Seismograph - machine
Seismogram –
seismic wave
display record

26. Types of Seismic Waves

27. Primary Waves (P Waves)
• A type of seismic wave that compresses
and expands the ground
• The first wave to arrive at an
earthquake

28. Secondary Waves (S Waves)
• A type of seismic wave that moves the
ground up and down or side to side
http://daphne.meccahosting.com/~a0000e89/insideearth2.htm

29. Comparing Seismic Waves

30. Surface Waves (L Waves)
• Move along the
Earth’s surface
• Travel more
slowly than S
and P waves
• More destructive

33. Typical Seismogram
start finish
How much time elapsed between the arrival of the
P wave (start) and the arrival of the S wave (finish)?

43. Tsunami
a large ocean wave usually caused by an
underwater earthquake or a volcanic
explosion.