Page 2 - Microsoft Word - 12.1 INTRODUCTION TO NATURAL DISASTER AND EARTHQUAKE
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EARTHQUAKE:
• An earthquake is the shaking of the surface of
Earth due to the sudden release of energy in
the Earth’s crust, as a result, seismic
waves (also known as S waves)are created.
What is an Earthquake?
An earthquake is the shaking of the surface of Earth due to the sudden release of
energy in the Earth’s crust, as a result, seismic waves (also known as S waves)are
created.
The seismic activities in an area determine the type and intensity of the earthquake.
What Causes an Earthquake?
Earthquakes are caused due to sudden tectonic movements in the earth’s crust.
When the tectonic plates slide over one another, there is a cause of orogeny which
results in earthquakes and volcanoes.
These disturbances cause vibrations that spread in all directions.
Tectonic plates
As there is a relative motion of these plates, there is stress built up, which breaks by
releasing the stored energy known as shock waves.
The point below the Earth’s surface where the earth quake starts is called as
HYPOCENTRE. The point directly above the hypocentre on the surface of the Earth is
known as the EPICENTRE. Generally, the maximum amount of impact is felt at the
epicentre.
How it is measured?
