Introduction

The sudden vibration of the earth,s surface by rapid release of energy called earthquake
this energy is released when two parts of rock masses move suddenly in relation to each other along the fault.

Effects

following are major effects of earthquake
1)  Buildings are damaged , causing losses to people lifes etc
2)  Roads are destroys , railways lines are twisted and bridges are destroyed.
3) In cities , ground waves disrupt underground services and start fires.
4) Rivers changes there courses.
5) Springs can be sprinkled out because of opening up fissures in the ground.
6) Land slides may occur in hilly areas
7) Permanent tilting may occur the some areas.

Classification depending due to surface causes

Earthquakes are classified in following types

a) Earthquakes due to  surface causes

These earthquakes are generally very minor in nature.the main source of these earthquakes are landslides and collapse of the under ground caves.

b) Earthquake due to volcanic causes

These are not very minor in nature these type of earthquakes produced by volcanic eruption feeble.

c) Earthquakes due to tectonic causes

These earthquake have high magnitude and most numerous and most dangerous
these earthquakes are caused by shocks which orginates in the earth of the crust due too sudden movement along faults,

Earthquake intesity scale

effect of an earthquake are strongest near the epicentre and decrease gradually outwards.
intensity is measrued by
1) Rossi Fovel scale
2) Richter scale

Control of earthquakes

In an earth quake prone area , if it is known that the strain is accumulating, the threat of eathquake can be reduced by
1) The number of deep holes are dirilled along a faulet line in which stress has been detected
then water is pumped down into the holes. this water acts as a lubricant.
2) Nuclear devies may be exploded along a fault plane which releive strain by producing small earthquakes
3) Buy building earthquakes resisting structures

That,s all knowledge i have.