1. Good Friday Alaskan Earthquake

2. 8.3 Destruction from Earthquakes
Seismic Vibrations (Shaking)
8.3 Destruction from Earthquakes
Damage to buildings and other structures from earthquake waves depends on:
Intensity and duration of the vibrations
The material on which the structure is built
The design of the structure.

3. 8.3 Destruction from Earthquakes
Seismic Vibrations
8.3 Destruction from Earthquakes
 Building Design
• Factors that determine structural damage
Stone or brick buildings are the most serious safety threats
Steel is better than stone or brick
- Nature of the material upon which the structure rests- sands are the worst

4. Earthquake Damage

5. Earthquake Design

6. 8.3 Destruction from Earthquakes
Seismic Vibrations
8.3 Destruction from Earthquakes
 Liquefaction
• Saturated soil material turns fluid
• Underground objects may float to surface

7. Effects of Subsidence Due to Liquefaction

8. 8.3 Destruction from Earthquakes
Tsunamis
8.3 Destruction from Earthquakes
 Cause of Tsunamis
• A tsunami occurs when the vibration of a quake sets an underwater landslide into motion.
• Tsunami is the Japanese word for “seismic sea wave.”

9. Movement of a Tsunami
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10. 8.3 Destruction from Earthquakes
Other Dangers
8.3 Destruction from Earthquakes
 Landslides
• With many earthquakes, the greatest damage to structures is from landslides and ground subsidence, or the sinking of the ground triggered by vibrations.
 Fire
• In the San Francisco earthquake of 1906, most of the destruction was caused by fires that started when gas and electrical lines were cut.

11. Landslide Damage

12. Fire Resulting from an Earthquake