1. Earthquakes
MT 5

2. Background Review
At what type of plate boundaries do Earthquakes occur?
In which direction do the plates travel at this boundary?
Have you ever felt an earthquake? Describe the experience.
What are the steps of an earthquake drill or what should you do during an earthquake?

3. Background Review
Northridge Earthquake

4. Background Review
San Francisco Earthquake

5. Background Review
San Francisco Earthquake

6. Background Review
Indian Ocean Tsunami

7. What causes an earthquake?
Release of elastic energy from plates in Earth’s lithosphere
The plates slip at the boundary in the Earth’s lithosphere

8. Where does the elastic energy come from?
Earth’s Interior!!!

9. What is the Elastic Rebound Hypothesis?
The explanation for the release of energy stored in deformed rocks that spring back into their original place

10. What are the steps of an earthquake?
***Remember: Plate boundaries form fault lines
Plates on both sides of a fault push against each other & build up energy
Plates (rock/crust) bend, deform, and are broken.
Energy is released as seismic waves & this is shaking that is felt
Rocks return to undeformed shape.

11. Anatomy of an Earthquake

12. Where do earthquakes take place?
***Remember: Plate boundaries form fault lines
At a fault
Faults occur when enough stress builds up in rock to make it move.

13. What is the Epicenter? What is the Focus?
Epicenter & Focus are where an Earthquake occur.
Difference between them is their relation to the Earth’s crust
Energy released by an earthquake is greatest at the epicenter.

14. What is the Epicenter? What is the Focus?
found under the surface of the Earth.

15. What is the Epicenter? Epicenter:
Found on the surface of the Earth’s crust

16. What do we call the energy that is released???

17. What do we call the energy that is released???
A seismic wave!
A vibration that travels through Earth, carrying the energy released during an earthquake

18. Which scales are used to Measure Earthquakes?
Modified Mercalli Scale
Richter scale

19. Which scales are used to Measure Earthquakes?
Modified Mercalli Scale
Measures intensity.
Tool Used:
Observations, GPS, Satellites
Has 12 steps – Roman Numerals
Lower numbers = what is felt by people.
Higher numbers = observed structural damage.

20. Which scales are used to Measure Earthquakes?
Richter Scale
Measures magnitude
Tool Used
Seismograph
Low is a 1 and high is 8 or more
It is a logarithmic scale
each level has 10 times the magnitude of the level below it.
Ex: A magnitude of 4.0 is 10x MORE than a magnitude of 3.0
***Does NOT measure damage. Earthquakes in two different places can have the same magnitude but not the same intensity-one can cause MORE damage.
Bill Nye – Richter Video