1. Earthquakes - Seismology
Earthquake – The release of energy (seismic waves) from rock layers moving along a fault

2. Kobe, Japan Earthquake January 17, 1995

3. 1994 Northridge earthquake (near LA) –
6.7 M
1989 Loma Prieta earthquake (Bay Bridge) near San Francisco (6.9 M)

4. 1960 Chile earthquake (9.5 M) – highest ever recorded
1964 Alaskan earthquake (9.2 M) – 2nd highest ever

5. 2010 Haiti earthquake (7.0 M)
Dec 26th 2004 tsunami earthquake (9.1 M)

6. What causes an earthquake?
STRESS!!!
Plastic Deformation AND Elastic Deformation
Stress builds along a fault causing elastic deformation & then an earthquake (elastic rebound)

7. Where do earthquakes occur?
Faults - a break in rock where movement occurs
Plate Boundaries (most of the time)
Interior of Plates (sometimes)
Recent California Earthquakes:
Interesting Facts: There are about 1,000,000 earthquakes a year; ONLY about 20 are considered severe

8. Focus vs. Epicenter

9. Seismic Body Waves: P vs. S Waves
Body Waves move through the Earth & start at the Focus
P waves –
Primary Wave
push-pull motion;
fastest wave;
travel through solids & liquids
S waves
Secondary Wave
side to side motion;
slower than P wave;
cannot travel through liquid

10. Seismic Wave Simulations
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11. Surface Seismic Waves
Surface waves – travels across Earth’s surface; starts at the epicenter; are slow moving, do not travel as far & cause the most damage (L wave)

12. Seismographs vs. Seismograms
Seismogram example
Seismogram
S-P Lag Time Example:

13. Locating an Epicenter Determine S-P lag time
Use Travel-Time Graph to determine distance to epicenter
Use compass to pinpoint epicenter
Need three locations to TRIANGULATE the epicenter location

14. Virtual Earthquake Class Example
Select Japan OR Southern California