1. Earthquakes Chapter 8
Earthquake - vibration of the earth caused by
slippage along a fault.
Characteristics
1. Focus- point in the Earth where a quake begins.
2. Epicenter- point on the surface above the focus.
3. Aftershock- small quake following a major quake.
4. Foreshock- small quake before a major quake.
Cause
Elastic Rebound Hypothesis
- release of energy stored in deformed rocks.

3. Elastic Rebound Hypothesis

4. Slippage along a fault

5. Measuring Quakes 1. Detection - Seismograph – instrument that records
earthquake waves.
Wave Types
1. Surface Waves- waves on Earth’s outer layer.
2. Body Waves- waves in Earth’s interior.
- P Waves- push-pull waves(1st)
- S Waves- waves acting at right angles(2nd)

6. Seismograph

7. Seismogram

8. Types of Waves

9. 2. Locating Epicenter
- 3 or more seismograph stations measure the
time it takes for waves to travel.
3. Magnitude
- Richter Scale
- measures strongest recorded waves
- Moment Magnitude
- measures energy released

10. The Richter Scale Richter Magnitude TNT Energy Equivalent Example
Richter Magnitude TNT Energy Equivalent Example
ounces
pounds
pounds
pounds
pounds
,000 pounds
tons Small Atomic Bomb
tons Average Tornado
tons
tons Massena, NY, 1994
tons
,550 ton Coalinga, CA, 1983
,000 tons Hebgen Lake, MT 1959
,000,000 tons
,270,00 tons San Francisco, CA 1906
,550,000 tons Anchorage, AK, 1964
,999,000 tons

11. Locating Earthquakes

12. Dangers of Earthquakes
1. Liquefaction
- wet soil turns liquid
- causes ground to collapse
2. Tsunami
- vibrations create giant ocean waves
3. Landslide
- vibrations cause soil to break loose

13. TSUNAMI

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