1. CAL LESSON CLASS - V SUB - EVS LESSON - WHEN THE EARTH SHOOK ! BY
Dr.C.RAJMOHAN,PRT
KV,THIRUVARUR.

2. EARTHQUAKES: WHY? AND HOW?

3. EARTHQUAKES sudden movement or shaking of the Earth
Caused by plate tectonic stresses
Located at plate boundaries
Resulting in breakage of the Earth’s brittle crust

4. PLATE TECTONIC STRESSES

5. EARTHQUAKE DAMAGE
Landsides
Building damage
Liquefaction

6. LIQUEFACTION
when a solid (sand and soil) becomes saturated with water and acts like a heavy liquid
Results in a loss of soil strength & the ability of the soil to support weight

7. EARTHQUAKE DAMAGE
Most caused by SURFACE waves (arrive last)

8. EARTHQUAKE WAVES Seismographs record earthquake waves
Surface waves move along surface – not felt opposite side of earth

9. EARTHQUAKE WAVES P waves move through solids & liquids
Notes: Surface waves cause most damage (“L” waves – feel like ocean waves)
Body waves move through the earth
p & s are Body waves – move through the earth
S waves move through solids only!!!

10. EARTHQUAKE WAVES Lets test your understanding!!
Is this a P or an S wave?
P wave!
S Wave
Surface waves cause most damage (“L” waves – feel like ocean waves)
Body waves move through the earth
Surface waves move along surface – not felt opposite side of earth

11. The effects of earthquakes also include other disasters such as,
TSUNAMI
FIRE
FLOOD

12. TSUNAMI
The tsunami of the 2004 Indian Ocean earthquake

13. FIRE
Earthquakes can cause fires by damaging electrical power or gas lines

14. FLOOD
 Earthquakes may cause landslips to dam rivers, which collapse and cause floods.

16. Thank you