2. Earthquakes Presented you to by the Hazard Committee Madeline Galac Nicole Barstrom

3. Where Do Earthquakes Occur? Earthquakes normally occur on plate boundaries.

4. Types of Plate Boundaries Spreading Zone - This is an area where two plates are moving apart from one another - One example is the Mid-Atlantic Ridge Transform Fault - This is where two plates are sliding past each other - One example is the San Andreas Fault on the coast of California and Northwestern Mexico Subduction Zone - This is where one plate moves on top of another causing one to be subducted into the mantle where it melts. - One example is the Western Coast of South America near Chile.

5. Earthquakes: Strong vs. Weak Strong Earthquakes:  Occur deeper in the crust  Are associated with Subduction Zones  Do not produce Surface Waves Weak Earthquakes:  Occur closer to the surface of the Earth  Are associated with Transform Faults and Spreading Zones  Are also associated with quakes not related to plate tectonics  Produce surface waves

6. Direct Effects of Earthquakes Ground shaking Disruption of Utilities Damage to personal items and buildings Water table adjustment Aftershocks

7. Indirect Effects of Earthquakes Ground failures Landslides Subsidence (drop in elevation of land due to removal of water) Liquefaction (reduction in the strength of saturated soils) Tsunamis (tidal waves) Flooding Seiches (movement of inland bodies of water) Fires from electrical difficulties

8. Earthquake Prediction Although it is likely to predict where an earthquake may occur, it is virtually impossible to predict when and of what magnitude. However, there are some signs that some scientists believe characterize earthquake events as was seen in the Haicheng Earthquake in 1975.

9. Possible Signs of an Earthquake  Changes in land elevation and ground water levels  Peculiar animal behavior  Regional increase of seismicity (foreshocks)

10. Stick Slip Experiment This experiment showed that earthquakes are nearly impossible to predict as far as specific details are concerned. It showed, though, that if an area that is prone to seismic activity has received a few small quakes in the recent past without a big event, that there should be a big quake in the near future.