1. EARTHQUAKES, SEISMIC WAVES, & MONITORING SYSTEMS

2. Earthquake Shaking and trembling from movement of the Earth’s plates
More than 8,000 quakes everyday
Focus-point where earthquake begins
Epicenter- point on Earth’s surface above the focus

3. Seismic Waves Carry energy away from the earthquake
P wave: 1st waves and they compress and expand
S wave: secondary waves and they vibrate side to side
Surface wave: travel on the surface and produce ground movement

4. P-wave
S-wave

5. Measuring Earthquakes
Mercalli Scale- measures the amount of damage on a scale of 1-12

6. Measuring Earthquakes (2)
Richter scale-measures an earthquake’s magnitude (strength)
Seismograph- measures wave strength

7. Measuring Earthquakes (3)
Movement Magnitude Scale: estimates the total energy released by the earthquake

8. Comparing Magnitudes
One-point increase in magnitude represents 32 times as much energy as the one before

9. Locating the Epicenter
Seismic waves are used. P waves travel faster than S waves

10. Locating the Epicenter

11. The Modern Seismograph
Seismic waves cause a drum to vibrate while an attached pen records the vibrations

12. Instruments to Monitor Faults (Predicting Earthquakes)
Tiltmeters- measures the raising of the ground
Creep Meters- a wire measures horizontal movement of the ground

13. More Instruments
Laser-Ranging Devices: a laser detects horizontal fault movements
GPS satellites: Monitor changes in elevation and hroizontal movements with satellites

14. Mapping Faults Scientists study faults and the movement along them
Friction- force that opposes motion of one object sliding over another object

15. Predicting Earthquakes
Scientists use their monitoring tools and fault maps to make predictions but there is no effective early warning system