ppt on earthquake

2. A series of shock waves in
the earth's crust upper
mantle. They are the
earth's natural means of
releasing stress.

3.  These stresses develop because of instability
in the geological formations below the earth
due to the presence of fault planes and other
stressful environments like the internal heat
of the earth.
 When this stress is increased beyond a
point, the earth's crust is forced to break.
The stress is released as energy which moves
through the earth in the form of waves.

4. Surface Waves Travel through
the surface of the earth.
Body Waves Travel through
the body of the earth getting
reflected and refracted in the
process.

5. A logarithmic scale used for
comparing the magnitude of
earthquakes. It was invented
by an American Seismologist,
Charles Richter in 1935.

7. Magnitude represents the
amount of energy released by
an earthquake as determined
by measurements on
standardised instruments.
The scale ranges from 0 to 10.

9. It is more subjective in assessing
the effect of earthquakes.
An earthquake measuring 12 on the
Mercalli scale would have
destroyed all man-made objects;
and created new topography by
forming new lakes, huge falls of
rock and major earth faults.

11. Earthquakes triggered
either on the main-shock
fault- a fracture in the
rock- or near it. Bigger
earthquakes have more
and larger aftershocks.