earthquake and natural disasters ppt

1. Earthqua
ke

2. What is an
earthquake?
 Earthquake are the shaking rolling or
sudden shock of the earth surface..
 They are the Earth natural means of
releasing stress..Webpage

3. What causes an
earthquake?
 There are about 20 plates along the surface
of the earth that move continuously and
slowly past each other.When the plates
squeeze or stretch huge rocks form at their
edges and the rocks shift with great force
,causing an earthquake..

4. What is a fault?
 A fault is an area of stress in the earth
where broken rocks slide past each other
causing a crack in the Earth surface…
 There are four major types of fault which
are as follows:dip-slip normal,dip-slip
reverse,strike slip,and oblique-slip.

5. What is a
seismograph?
 A seimograph is an instrument used for recording
the intensity and duration of an earthquake..
What is a tsunami?
 A tsunami is a large ocean wave usually caused
by an underwater earthquake or volcanic
explosion.

6.  Tsunamis are not tidal waves.
 Tidal waves are caused by the forces of
the moon,sun and planet upon the
tides,as well as the wind as it moves over
the water.

7. How we measure
the earthquakes?
 Richter scale:Is a seismic scale which measure the
magnitude of an earthquake.
 Mercalli scale:Is a seismic scale which measure the
intensity of an earthquake.
 The instrument that is used for measure an
earthquake is called seismograph.

8. Disadvantages of
Earthquake:
 The destruction of the building and
structures such as “houses” collapsed and
bridges broken down,cracking dams ,rail
deformation and so on.
 The destruction of natural objects such as
mountains and landslides etc.