1. Small Scale Crustal Change: Deformation of Earth’s Crust
Earth Science
Mr. Cloud
1906 San Francisco Earthquake

2. Original Horizontality
Sediment is always deposited horizontally
Rocks form in horizontal layers that run parallel to the ground
Strata: layers of rock

3. Deformed Layers
Faulted:
Rocks that have been offset or displaced

4. Types of Faults

5. Deformed Layers
Folded:
Rocks that have been bent or curved

6. Mr. Cloud producing lateral strain. Look how he produces folds in rock
Mr. Cloud producing lateral strain! Look how he produces folds in rock! Deformation in ACTION!

7. Deformed Layers
Uplift:
Layers that have been raised.

9. Earthquake!
An earthquake is a natural rapid shaking of the lithosphere caused by the release of energy stored in rocks.
Most earthquakes are caused by the movement along faults.
Some are associated with volcanic eruptions or movement of magma in the lithosphere.

10. How does an Earthquake occur?
Rocks are elastic! (Think of a rubber band)
The Elastic Rebound Theory states that if pressure is applied, a rock will deform under stress.
If the stress becomes too great, it will break and rebound. (similar to a rubber band)
The energy released during the break causes the ground to shake.
Break a pencil!

11. How is all this energy transported?
The potential energy stored in rocks is given off as seismic waves.
Two Types of Seismic Waves:
1. Body Waves ***
P-Waves: Primary
S-Waves: Secondary
2. Surface Waves
Love Waves
Rayleigh Waves

12. How can seismic waves be measured?
Seismograph: instrument that measures seismic activity

13. Seismographs create seismograms!

14. Seismic Waves Help us Interpret Earth’s Interior

15. Focus and Epicenter

16. Triangulation: Locating the Epicenter of an Earthquake

17. What should you do to prepare for an Earthquake?

18. Two Ways to Measure an Earthquake
Richter Magnitude
Modified-Mercalli Intensity

19. Richter Magnitude
a scale used to express the seismic energy released by an earthquake

20. How is Richter Magnitude Determined?
The amplitude of seismic waves recorded by a seismograph determines Richter magnitude

21. The Richter Scale
The scale is a base-10 logarithmic scale. The magnitude is defined as the logarithm of the ratio of the amplitude of waves measured by a seismograph to an arbitrary small amplitude.
An earthquake that measures 5.0 on the Richter scale has a shaking amplitude 10 times larger than one that measures 4.0

22. Modified-Mercalli Intensity
The Mercalli intensity scale is a scale used for measuring the intensity of an earthquake.
The scale quantifies the effects of an earthquake on the Earth's surface, humans, objects of nature, and man-made structures on a scale of I through XII.