1. Earthquakes
February 2013

2. Earthquakes occur when plates move can happen at any plate boundaries
or fault lines
Earthquakes

3. Steps to an EQ
1. Stress forces rock to begin moving

4. 2. Rock undergoes Elastic Deformation (bends/buckles)
Steps to an EQ

5. Steps to an EQ
3. Rock Cracks

6. 4. Elastic Rebound: stressed rocks bounce back to undeformed shape
Steps to an EQ

8. http://earthquake. usgs. gov/learn/animations/animation. php

9. 3 Types of Earthquake Waves

10. P-waves
pressure or primary waves
first waves
compress the rock

11. S-waves
shear or secondary waves
second wave in a quake
move rock side to side

12. Surface waves
roll rock like water wave
most destructive
happen in the most severe quakes

15. Start Points Epicenter: point on surface above where quake occurs
Focus: point underground where quake began

16. Earthquake Words Seismology: study of earthquakes
Seismologist: person who studies quakes
Seismograph: instrument used to record quakes
Seismogram: reading from seismograph
Seismos: means “to shake”

17. Measuring Earthquakes
Richter Scale- Numbers 1-10
each interval increases strength by 10 times
Mercalli Scale - uses Roman numerals I-XII to record intensity and damage
(damage differs based on structures in area)
Highest quake recorded-9.5 in Chile in 1960; number two 9.2 in Alaska

18. Earthquakes since the beginning of 2012