1. Seismology

2. I. Earthquakes
Rocks will bend and stretch up to a limit undergoing elastic deformation.
A fault is created when the rock finally breaks.
An earthquake is the vibrations produced by the breaking of the rock.

3. A. Types of Faults Normal Faults Tensional forces pull the rock apart.
Rock above the fault surface moves downward compared to the rock below the fault surface.

4. 2. Reverse Fault
Compression forces squeeze the rock.
Rock above the fault surface moves upward and over the rock below the fault surface.

5. 3. Strike-Slip Fault
Shear forces tear the rock.
Rocks on either side of the fault are moving past each other without upward or downward movement.

6. B. Seismic Waves
Waves generated by earthquakes that travel through the Earth.
1. Origin of Seismic Waves
a.) Focus- the point where the energy is first released.
Below the surface along the fault.
b.) Epicenter- point on the surface of the Earth directly above the focus

7. Fault line
Epicenter
Focus

8. 2. Types of Seismic Waves
a.) Primary Waves (P-Waves)
Particles in the rock move back and forth in the same direction the wave is traveling.
Travels trough solids, liquids, & gases
Fastest seismic waves

9. b.) Secondary Waves (S-Waves)
Particles in the rock move up and down at right angles to the direction of wave travel.
Travels through solids only.

10. c.) Surface Waves (L-Waves)
Particles in the rock move in a backward, rolling motion and a side-to-side, swaying motion.
Causes the most damage.
Originate from the epicenter.

11. 3. Locating an Epicenter
a.) Seismograph
Register the waves & record the time that each arrived.

12. Seismogram L Waves P Waves S Waves
1 min
Time between P & S waves = 3 minutes
Time for entire quake = 8 minutes

13. Data from three separate
stations are required to
locate the epicenter of
an earthquake.
The epicenter distance
is figured out using the time
difference between the P & S
waves graph.

15. II. Earthquake Activity
A. Magnitude
The amount of energy released in an earthquake.
Richter Scale- a numeric scale used to describe the strength (magnitude) of an earthquake.
Mercalli Scale- scale that describes the amount of damage.

16. B. Liquefaction
Wet soil can be strong most of the time, but the shaking from an earthquake can cause it to act like a liquid.
This causes soil to sink into the ground and cause things to collapse.

17. C. Tsunamis
Under water earthquakes cause the water to shake forming large waves.
Seismic sea waves
Wave crests can reach m in height by the time it reaches shore.