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

EARTHQUAKES: WHY? AND HOW?

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

PLATE TECTONIC STRESSES

EARTHQUAKE DAMAGE Landsides Building damage Liquefaction

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

EARTHQUAKE DAMAGE Most caused by SURFACE waves (arrive last)

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

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 http://earthquake.usgs.gov/learning/animations/ S waves move through solids only!!!

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

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

TSUNAMI The tsunami of the 2004 Indian Ocean earthquake

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

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

Thank you