1. Magnitude 7.6, Sumatra, Sept 30 2009

2. Where do Earthquakes Occur?
Earthquakes occur along plate boundaries, MOST OF THE TIME. However, earthquakes can occur anywhere.
One of the interesting things is how in some places earthquakes deepen as you go away from plate boundaries
These occur along subduction zones. Why?
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5. Where do earthquakes occur?
A closer look
Faults
Listric faults (large landslides: gravitational collapse of volcanic edifices)
Around Volcanos
“Anthropogenic Earthquakes”
Collapse of mine shafts
Explosions

6. The Kursk Disaster
On August 12, 2000 the Russian Oscar-Class Submarine, Kursk
sank, killing all aboard… What happened (and what does this have
to do with earthquakes)?
Seismology (the study of earthquakes) gave clues about what happened.
Russian officials later admitted that the disaster was the result of a faulty torpedo.
Lesson: You Can’t Hide Big Explosions

7. October 8, 2006 North Korea Nuclear Test

8. Earthquakes come in all shapes and sizes
shear)
Earthquakes come in all shapes and sizes
Right vs. Left Lateral
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9. Qualitative measurement depends on:
INTENSITY: Amount of ground motion = Destructive Power
Qualitative measurement depends on:
Magnitude
Distance from focus
Depth of focus
Rock type
Building type
MAGNITUDE: Quantitative measure of the amount of energy released. The Richter Scale is logarithmic.

10. Did you feel it? earthquakes.usgs.gov

11. The Richter Scale is Logarithmic

12. Press and Siever

13. How Big is Big?
If the ENTIRE San Andreas Fault ruptured at once…

14. Percent Chance of a strong to great earthquake in the next 30 years along the San Andreas Fault

15. What happens during an earthquake?

16. Types of deformation
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18. What happens during an earthquake?
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19. May 24, 2006 Magnitude 5.4

20. Surface Rupture
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21. What happens during an Earthquake?
Kobe, Japan
January, 1995
Magnitude 6.9

22. SEISMIC WAVES
The energy of an earthquake is dissipated by waves
P (“primary”) Waves
Compressional
Push-pull motion
Transmitted through liquids
S (“secondary”) Waves
Shear
Side-to-side (and up-and-down) motion
Slower than P waves
Not transmitted through liquids
Surface Waves
Rayleigh waves (rotational motion, think waves in water)
Love waves (Side-to-side motion)

23. P Waves
S Waves
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24. Rayleigh Waves
Love Waves
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